Merge remote-tracking branch 'micropython/master'

Conflicts:
	README.md - Kept Adafruit README.md intact.
	py/emitglue.c - Added xtensa architecture as an OR of the define.
	zephyr/README.md - Fixed spelling mistake.

170 files changed, 1961 insertions, 787 deletions

diff --git a/cc3200/hal/cc3200_hal.c b/cc3200/hal/cc3200_hal.c
index f4d38d120..37026db14 100644
--- a/cc3200/hal/cc3200_hal.c
+++ b/cc3200/hal/cc3200_hal.c
@@ -130,10 +130,6 @@ void mp_hal_delay_ms(mp_uint_t delay) {
     }
 }
 
-NORETURN void mp_hal_raise(int errno) {
-    nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, mp_obj_new_int(errno)));
-}
-
 void mp_hal_set_interrupt_char (int c) {
     mpexception_set_interrupt_char (c);
 }
diff --git a/cc3200/hal/cc3200_hal.h b/cc3200/hal/cc3200_hal.h
index 054d5035a..9715096b6 100644
--- a/cc3200/hal/cc3200_hal.h
+++ b/cc3200/hal/cc3200_hal.h
@@ -62,7 +62,6 @@
 extern void HAL_SystemInit (void);
 extern void HAL_SystemDeInit (void);
 extern void HAL_IncrementTick(void);
-extern NORETURN void mp_hal_raise(int errno);
 extern void mp_hal_set_interrupt_char (int c);
 
 #endif /* CC3200_LAUNCHXL_HAL_CC3200_HAL_H_ */
diff --git a/cc3200/misc/mpirq.c b/cc3200/misc/mpirq.c
index 29cc4a7bd..4389ab0c3 100644
--- a/cc3200/misc/mpirq.c
+++ b/cc3200/misc/mpirq.c
@@ -112,7 +112,7 @@ void mp_irq_remove (const mp_obj_t parent) {
 
 uint mp_irq_translate_priority (uint priority) {
     if (priority < 1 || priority > MP_ARRAY_SIZE(mp_irq_priorities)) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
     return mp_irq_priorities[priority - 1];
 }
diff --git a/cc3200/mods/modmachine.c b/cc3200/mods/modmachine.c
index f82decda2..8a57c2eb4 100644
--- a/cc3200/mods/modmachine.c
+++ b/cc3200/mods/modmachine.c
@@ -130,7 +130,7 @@ STATIC mp_obj_t machine_main(mp_obj_t main) {
     if (MP_OBJ_IS_STR(main)) {
         MP_STATE_PORT(machine_config_main) = main;
     } else {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
     return mp_const_none;
 }
diff --git a/cc3200/mods/modnetwork.c b/cc3200/mods/modnetwork.c
index 8e086b1d2..f98d9a88a 100644
--- a/cc3200/mods/modnetwork.c
+++ b/cc3200/mods/modnetwork.c
@@ -101,7 +101,7 @@ STATIC mp_obj_t network_server_make_new(const mp_obj_type_t *type, mp_uint_t n_a
     // check the server id
     if (args[0].u_obj != MP_OBJ_NULL) {
         if (mp_obj_get_int(args[0].u_obj) != 0) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+            mp_raise_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable);
         }
     }
 
diff --git a/cc3200/mods/moduhashlib.c b/cc3200/mods/moduhashlib.c
index 93f15540c..46f30be21 100644
--- a/cc3200/mods/moduhashlib.c
+++ b/cc3200/mods/moduhashlib.c
@@ -93,7 +93,7 @@ STATIC void hash_update_internal(mp_obj_t self_in, mp_obj_t data, bool digest) {
             self->digested = false;
         }
     } else {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_request_not_possible);
     }
 }
 
@@ -106,7 +106,7 @@ STATIC mp_obj_t hash_read (mp_obj_t self_in) {
         }
     } else if (self->c_size < self->b_size) {
         // it's a fixed len block which is still incomplete
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_request_not_possible);
     }
 
     if (!self->digested) {
diff --git a/cc3200/mods/moduos.c b/cc3200/mods/moduos.c
index 8e3e0135e..d5b29336a 100644
--- a/cc3200/mods/moduos.c
+++ b/cc3200/mods/moduos.c
@@ -158,7 +158,7 @@ STATIC void mount (mp_obj_t device, const char *path, uint pathlen, bool readonl
 #endif
     // cannot mount twice or on existing paths
     if (f_stat(path, &fno) == FR_OK || osmount_find_by_device(device)) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_request_not_possible);
     }
 
     // create a new object
@@ -196,7 +196,7 @@ STATIC void mount (mp_obj_t device, const char *path, uint pathlen, bool readonl
     if (f_mount(&self->fatfs, self->path, 1) != FR_OK) {
         // remove it and raise
         mp_obj_list_remove(&MP_STATE_PORT(mount_obj_list), self);
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
     }
 
     // mount succeeded, increment the count
@@ -252,7 +252,7 @@ STATIC mp_obj_t os_chdir(mp_obj_t path_in) {
     }
 
     if (res != FR_OK) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
     }
 
     return mp_const_none;
@@ -263,7 +263,7 @@ STATIC mp_obj_t os_getcwd(void) {
     char buf[MICROPY_ALLOC_PATH_MAX + 1];
     FRESULT res = f_getcwd(buf, sizeof buf);
     if (res != FR_OK) {
-        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(fresult_to_errno_table[res])));
+        mp_raise_OSError(fresult_to_errno_table[res]);
     }
     return mp_obj_new_str(buf, strlen(buf), false);
 }
@@ -303,7 +303,7 @@ STATIC mp_obj_t os_listdir(mp_uint_t n_args, const mp_obj_t *args) {
 
         res = f_opendir(&dir, path);                       /* Open the directory */
         if (res != FR_OK) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+            mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
         }
 
         for ( ; ; ) {
@@ -335,10 +335,10 @@ STATIC mp_obj_t os_mkdir(mp_obj_t path_o) {
         case FR_OK:
             return mp_const_none;
         case FR_EXIST:
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+            mp_raise_msg(&mp_type_OSError, mpexception_os_request_not_possible);
             break;
         default:
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+            mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
     }
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(os_mkdir_obj, os_mkdir);
@@ -351,7 +351,7 @@ STATIC mp_obj_t os_rename(mp_obj_t path_in, mp_obj_t path_out) {
         case FR_OK:
             return mp_const_none;
         default:
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+            mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
     }
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(os_rename_obj, os_rename);
@@ -363,7 +363,7 @@ STATIC mp_obj_t os_remove(mp_obj_t path_o) {
         case FR_OK:
             return mp_const_none;
         default:
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+            mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
     }
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(os_remove_obj, os_remove);
@@ -394,7 +394,7 @@ STATIC mp_obj_t os_stat(mp_obj_t path_in) {
         fno.ftime = 0;
         fno.fattrib = AM_DIR;
     } else if ((res = f_stat(path, &fno)) != FR_OK) {
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(fresult_to_errno_table[res])));
+        mp_raise_OSError(fresult_to_errno_table[res]);
     }
 
     mp_obj_tuple_t *t = mp_obj_new_tuple(10, NULL);
@@ -481,7 +481,7 @@ STATIC mp_obj_t os_mount(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *k
     return mp_const_none;
 
 invalid_args:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_value_invalid_arguments));
+    mp_raise_msg(&mp_type_OSError, mpexception_value_invalid_arguments);
 }
 MP_DEFINE_CONST_FUN_OBJ_KW(os_mount_obj, 2, os_mount);
 
@@ -490,7 +490,7 @@ STATIC mp_obj_t os_unmount(mp_obj_t path_o) {
 
     // '/flash' cannot be unmounted, also not the current working directory
     if (path_equal(path, "/flash")) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_request_not_possible);
     }
 
     // now unmount it
@@ -498,7 +498,7 @@ STATIC mp_obj_t os_unmount(mp_obj_t path_o) {
     if ((mount_obj = osmount_find_by_path(path))) {
         unmount (mount_obj);
     } else {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_msg(&mp_type_ValueError, mpexception_value_invalid_arguments);
     }
 
     return mp_const_none;
@@ -515,7 +515,7 @@ STATIC mp_obj_t os_mkfs(mp_obj_t device) {
         path = mp_obj_str_get_str(device);
         // otherwise the relative path check will pass...
         if (path[0] != '/') {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_value_invalid_arguments));
+            mp_raise_msg(&mp_type_OSError, mpexception_value_invalid_arguments);
         }
     } else {
         // mount it briefly
@@ -541,7 +541,7 @@ STATIC mp_obj_t os_mkfs(mp_obj_t device) {
     }
 
     if (res != FR_OK) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
     }
     return mp_const_none;
 }
diff --git a/cc3200/mods/modusocket.c b/cc3200/mods/modusocket.c
index c7b3fb203..81a4c2e19 100644
--- a/cc3200/mods/modusocket.c
+++ b/cc3200/mods/modusocket.c
@@ -156,7 +156,7 @@ STATIC mp_obj_t socket_make_new(const mp_obj_type_t *type, mp_uint_t n_args, mp_
     // create the socket
     int _errno;
     if (wlan_socket_socket(s, &_errno) != 0) {
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(-_errno)));
+        mp_raise_OSError(-_errno);
     }
     // add the socket to the list
     modusocket_socket_add(s->sock_base.sd, true);
@@ -182,7 +182,7 @@ STATIC mp_obj_t socket_bind(mp_obj_t self_in, mp_obj_t addr_in) {
     // call the NIC to bind the socket
     int _errno;
     if (wlan_socket_bind(self, ip, port, &_errno) != 0) {
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(-_errno)));
+        mp_raise_OSError(-_errno);
     }
     return mp_const_none;
 }
@@ -200,7 +200,7 @@ STATIC mp_obj_t socket_listen(mp_uint_t n_args, const mp_obj_t *args) {
 
     int _errno;
     if (wlan_socket_listen(self, backlog, &_errno) != 0) {
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(-_errno)));
+        mp_raise_OSError(-_errno);
     }
     return mp_const_none;
 }
@@ -220,7 +220,7 @@ STATIC mp_obj_t socket_accept(mp_obj_t self_in) {
     mp_uint_t port;
     int _errno;
     if (wlan_socket_accept(self, socket2, ip, &port, &_errno) != 0) {
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(-_errno)));
+        mp_raise_OSError(-_errno);
     }
 
     // add the socket to the list
@@ -248,7 +248,7 @@ STATIC mp_obj_t socket_connect(mp_obj_t self_in, mp_obj_t addr_in) {
         if (!self->sock_base.cert_req && _errno == SL_ESECSNOVERIFY) {
             return mp_const_none;
         }
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(-_errno)));
+        mp_raise_OSError(-_errno);
     }
     return mp_const_none;
 }
@@ -262,7 +262,7 @@ STATIC mp_obj_t socket_send(mp_obj_t self_in, mp_obj_t buf_in) {
     int _errno;
     mp_int_t ret = wlan_socket_send(self, bufinfo.buf, bufinfo.len, &_errno);
     if (ret < 0) {
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(-_errno)));
+        mp_raise_OSError(-_errno);
     }
     return mp_obj_new_int_from_uint(ret);
 }
@@ -278,9 +278,9 @@ STATIC mp_obj_t socket_recv(mp_obj_t self_in, mp_obj_t len_in) {
     mp_int_t ret = wlan_socket_recv(self, (byte*)vstr.buf, len, &_errno);
     if (ret < 0) {
         if (_errno == EAGAIN && self->sock_base.has_timeout) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TimeoutError, "timed out"));
+            mp_raise_msg(&mp_type_TimeoutError, "timed out");
         }
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(-_errno)));
+        mp_raise_OSError(-_errno);
     }
     if (ret == 0) {
         return mp_const_empty_bytes;
@@ -307,7 +307,7 @@ STATIC mp_obj_t socket_sendto(mp_obj_t self_in, mp_obj_t data_in, mp_obj_t addr_
     int _errno;
     mp_int_t ret = wlan_socket_sendto(self, bufinfo.buf, bufinfo.len, ip, port, &_errno);
     if (ret < 0) {
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(-_errno)));
+        mp_raise_OSError(-_errno);
     }
     return mp_obj_new_int(ret);
 }
@@ -324,9 +324,9 @@ STATIC mp_obj_t socket_recvfrom(mp_obj_t self_in, mp_obj_t len_in) {
     mp_int_t ret = wlan_socket_recvfrom(self, (byte*)vstr.buf, vstr.len, ip, &port, &_errno);
     if (ret < 0) {
         if (_errno == EAGAIN && self->sock_base.has_timeout) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TimeoutError, "timed out"));
+            mp_raise_msg(&mp_type_TimeoutError, "timed out");
         }
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(-_errno)));
+        mp_raise_OSError(-_errno);
     }
     mp_obj_t tuple[2];
     if (ret == 0) {
@@ -364,7 +364,7 @@ STATIC mp_obj_t socket_setsockopt(mp_uint_t n_args, const mp_obj_t *args) {
 
     int _errno;
     if (wlan_socket_setsockopt(self, level, opt, optval, optlen, &_errno) != 0) {
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(-_errno)));
+        mp_raise_OSError(-_errno);
     }
     return mp_const_none;
 }
@@ -384,7 +384,7 @@ STATIC mp_obj_t socket_settimeout(mp_obj_t self_in, mp_obj_t timeout_in) {
     }
     int _errno;
     if (wlan_socket_settimeout(self, timeout, &_errno) != 0) {
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(-_errno)));
+        mp_raise_OSError(-_errno);
     }
     return mp_const_none;
 }
@@ -408,7 +408,7 @@ STATIC mp_obj_t socket_makefile(mp_uint_t n_args, const mp_obj_t *args) {
     if (n_args > 1) {
         const char *mode = mp_obj_str_get_str(args[1]);
         if (strcmp(mode, "rb") && strcmp(mode, "wb")) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+            mp_raise_ValueError(mpexception_value_invalid_arguments);
         }
     }
     return self;
@@ -504,7 +504,7 @@ STATIC mp_obj_t mod_usocket_getaddrinfo(mp_obj_t host_in, mp_obj_t port_in) {
     uint8_t out_ip[MOD_NETWORK_IPV4ADDR_BUF_SIZE];
     int32_t result = wlan_gethostbyname(host, hlen, out_ip, AF_INET);
     if (result < 0) {
-        nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(-result)));
+        mp_raise_OSError(-result);
     }
     mp_obj_tuple_t *tuple = mp_obj_new_tuple(5, NULL);
     tuple->items[0] = MP_OBJ_NEW_SMALL_INT(AF_INET);
diff --git a/cc3200/mods/modussl.c b/cc3200/mods/modussl.c
index 1f27bdd21..7a4787b6b 100644
--- a/cc3200/mods/modussl.c
+++ b/cc3200/mods/modussl.c
@@ -131,10 +131,10 @@ STATIC mp_obj_t mod_ssl_wrap_socket(mp_uint_t n_args, const mp_obj_t *pos_args,
     return ssl_sock;
 
 socket_error:
-    nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(_errno)));
+    mp_raise_OSError(_errno);
 
 arg_error:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(mod_ssl_wrap_socket_obj, 0, mod_ssl_wrap_socket);
 
diff --git a/cc3200/mods/modutime.c b/cc3200/mods/modutime.c
index bef8b667f..7ea8df1ef 100644
--- a/cc3200/mods/modutime.c
+++ b/cc3200/mods/modutime.c
@@ -29,7 +29,7 @@
 #include <string.h>
 
 #include "py/mpconfig.h"
-#include "py/nlr.h"
+#include "py/runtime.h"
 #include "py/obj.h"
 #include "py/smallint.h"
 #include "py/mphal.h"
@@ -109,7 +109,7 @@ STATIC mp_obj_t time_mktime(mp_obj_t tuple) {
 
     // localtime generates a tuple of len 8. CPython uses 9, so we accept both.
     if (len < 8 || len > 9) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, mpexception_num_type_invalid_arguments));
+        mp_raise_TypeError(mpexception_num_type_invalid_arguments);
     }
 
     return mp_obj_new_int_from_uint(timeutils_mktime(mp_obj_get_int(elem[0]), mp_obj_get_int(elem[1]), mp_obj_get_int(elem[2]),
diff --git a/cc3200/mods/modwlan.c b/cc3200/mods/modwlan.c
index 2fb7ed377..4b3dd4ec3 100644
--- a/cc3200/mods/modwlan.c
+++ b/cc3200/mods/modwlan.c
@@ -603,7 +603,7 @@ STATIC void wlan_reset (void) {
 
 STATIC void wlan_validate_mode (uint mode) {
     if (mode != ROLE_STA && mode != ROLE_AP) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
 }
 
@@ -614,7 +614,7 @@ STATIC void wlan_set_mode (uint mode) {
 
 STATIC void wlan_validate_ssid_len (uint32_t len) {
     if (len > MODWLAN_SSID_LEN_MAX) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
 }
 
@@ -647,7 +647,7 @@ STATIC void wlan_validate_security (uint8_t auth, const char *key, uint8_t len)
     return;
 
 invalid_args:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 
 STATIC void wlan_set_security (uint8_t auth, const char *key, uint8_t len) {
@@ -670,7 +670,7 @@ STATIC void wlan_set_security (uint8_t auth, const char *key, uint8_t len) {
 
 STATIC void wlan_validate_channel (uint8_t channel) {
     if (channel < 1 || channel > 11) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
 }
 
@@ -682,7 +682,7 @@ STATIC void wlan_set_channel (uint8_t channel) {
 #if MICROPY_HW_ANTENNA_DIVERSITY
 STATIC void wlan_validate_antenna (uint8_t antenna) {
     if (antenna != ANTENNA_TYPE_INTERNAL && antenna != ANTENNA_TYPE_EXTERNAL) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
 }
 
@@ -847,7 +847,7 @@ STATIC mp_obj_t wlan_make_new(const mp_obj_type_t *type, mp_uint_t n_args, mp_ui
     if (n_args > 1 || n_kw > 0) {
         // check the peripheral id
         if (args[0].u_int != 0) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+            mp_raise_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable);
         }
         // start the peripheral
         wlan_init_helper(self, &args[1]);
@@ -871,7 +871,7 @@ STATIC mp_obj_t wlan_scan(mp_obj_t self_in) {
 
     // check for correct wlan mode
     if (wlan_obj.mode == ROLE_AP) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_request_not_possible);
     }
 
     Sl_WlanNetworkEntry_t wlanEntry;
@@ -925,7 +925,7 @@ STATIC mp_obj_t wlan_connect(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_
 
     // check for the correct wlan mode
     if (wlan_obj.mode == ROLE_AP) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_request_not_possible);
     }
 
     // parse args
@@ -973,9 +973,9 @@ STATIC mp_obj_t wlan_connect(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_
     modwlan_Status_t status;
     status = wlan_do_connect (ssid, ssid_len, bssid, auth, key, key_len, timeout);
     if (status == MODWLAN_ERROR_TIMEOUT) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
     } else if (status == MODWLAN_ERROR_INVALID_PARAMS) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
     return mp_const_none;
 }
@@ -1004,7 +1004,7 @@ STATIC mp_obj_t wlan_ifconfig (mp_uint_t n_args, const mp_obj_t *pos_args, mp_ma
 
     // check the interface id
     if (args[0].u_int != 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable);
     }
 
     // get the configuration
@@ -1051,7 +1051,7 @@ STATIC mp_obj_t wlan_ifconfig (mp_uint_t n_args, const mp_obj_t *pos_args, mp_ma
             // check for the correct string
             const char *mode = mp_obj_str_get_str(args[1].u_obj);
             if (strcmp("dhcp", mode)) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+                mp_raise_ValueError(mpexception_value_invalid_arguments);
             }
 
             // only if we are not in AP mode
@@ -1165,7 +1165,7 @@ STATIC mp_obj_t wlan_mac (mp_uint_t n_args, const mp_obj_t *args) {
         mp_buffer_info_t bufinfo;
         mp_get_buffer_raise(args[1], &bufinfo, MP_BUFFER_READ);
         if (bufinfo.len != 6) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+            mp_raise_ValueError(mpexception_value_invalid_arguments);
         }
         memcpy(self->mac, bufinfo.buf, SL_MAC_ADDR_LEN);
         sl_NetCfgSet(SL_MAC_ADDRESS_SET, 1, SL_MAC_ADDR_LEN, (_u8 *)self->mac);
@@ -1201,7 +1201,7 @@ STATIC mp_obj_t wlan_irq (mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *
     return _irq;
 
 invalid_args:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(wlan_irq_obj, 1, wlan_irq);
 
@@ -1230,18 +1230,18 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_KW(wlan_irq_obj, 1, wlan_irq);
 //
 //        // the call to sl_NetAppSet corrupts the input string URN=args[1], so we copy into a local buffer
 //        if (len > MAX_DEVICE_URN_LEN) {
-//            nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+//            mp_raise_ValueError(mpexception_value_invalid_arguments);
 //        }
 //        strcpy(urn, p);
 //
 //        if (sl_NetAppSet(SL_NET_APP_DEVICE_CONFIG_ID, NETAPP_SET_GET_DEV_CONF_OPT_DEVICE_URN, len, (unsigned char *)urn) < 0) {
-//            nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+//            mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
 //        }
 //    }
 //    else {
 //        // get the URN
 //        if (sl_NetAppGet(SL_NET_APP_DEVICE_CONFIG_ID, NETAPP_SET_GET_DEV_CONF_OPT_DEVICE_URN, &len, (uint8_t *)urn) < 0) {
-//            nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+//            mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
 //        }
 //        return mp_obj_new_str(urn, (len - 1), false);
 //    }
diff --git a/cc3200/mods/pybadc.c b/cc3200/mods/pybadc.c
index 22a90edb0..f8c9b3da5 100644
--- a/cc3200/mods/pybadc.c
+++ b/cc3200/mods/pybadc.c
@@ -104,7 +104,7 @@ STATIC void pyb_adc_init (pyb_adc_obj_t *self) {
 STATIC void pyb_adc_check_init(void) {
     // not initialized
     if (!pyb_adc_obj.enabled) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_request_not_possible);
     }
 }
 
@@ -149,12 +149,12 @@ STATIC mp_obj_t adc_make_new(const mp_obj_type_t *type, mp_uint_t n_args, mp_uin
 
     // check the peripheral id
     if (args[0].u_int != 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable);
     }
 
     // check the number of bits
     if (args[1].u_int != 12) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
 
     // setup the object
@@ -173,7 +173,7 @@ STATIC mp_obj_t adc_init(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *k
     mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(args), &pyb_adc_init_args[1], args);
     // check the number of bits
     if (args[0].u_int != 12) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
     pyb_adc_init(pos_args[0]);
     return mp_const_none;
@@ -206,11 +206,11 @@ STATIC mp_obj_t adc_channel(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t
     if (args[0].u_obj != MP_OBJ_NULL) {
         ch_id = mp_obj_get_int(args[0].u_obj);
         if (ch_id >= PYB_ADC_NUM_CHANNELS) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_os_resource_not_avaliable));
+            mp_raise_ValueError(mpexception_os_resource_not_avaliable);
         } else if (args[1].u_obj != mp_const_none) {
             uint pin_ch_id = pin_find_peripheral_type (args[1].u_obj, PIN_FN_ADC, 0);
             if (ch_id != pin_ch_id) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+                mp_raise_ValueError(mpexception_value_invalid_arguments);
             }
         }
     } else {
@@ -277,7 +277,7 @@ STATIC mp_obj_t adc_channel_value(mp_obj_t self_in) {
 
     // the channel must be enabled
     if (!self->enabled) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_request_not_possible);
     }
 
     // wait until a new value is available
diff --git a/cc3200/mods/pybi2c.c b/cc3200/mods/pybi2c.c
index 5022e614f..d92782d8a 100644
--- a/cc3200/mods/pybi2c.c
+++ b/cc3200/mods/pybi2c.c
@@ -144,7 +144,7 @@ STATIC bool pyb_i2c_transaction(uint cmd) {
 STATIC void pyb_i2c_check_init(pyb_i2c_obj_t *self) {
     // not initialized
     if (!self->baudrate) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_request_not_possible);
     }
 }
 
@@ -256,7 +256,7 @@ STATIC void pyb_i2c_read_into (mp_arg_val_t *args, vstr_t *vstr) {
 
     // receive the data
     if (!pyb_i2c_read(args[0].u_int, (byte *)vstr->buf, vstr->len)) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
     }
 }
 
@@ -275,7 +275,7 @@ STATIC void pyb_i2c_readmem_into (mp_arg_val_t *args, vstr_t *vstr) {
     if (pyb_i2c_mem_addr_write (i2c_addr, (byte *)&mem_addr, mem_addr_size)) {
         // Read the specified length of data
         if (!pyb_i2c_read (i2c_addr, (byte *)vstr->buf, vstr->len)) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+            mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
         }
     }
 }
@@ -323,7 +323,7 @@ STATIC mp_obj_t pyb_i2c_init_helper(pyb_i2c_obj_t *self, const mp_arg_val_t *arg
     return mp_const_none;
 
 invalid_args:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 
 STATIC const mp_arg_t pyb_i2c_init_args[] = {
@@ -341,7 +341,7 @@ STATIC mp_obj_t pyb_i2c_make_new(const mp_obj_type_t *type, mp_uint_t n_args, mp
 
     // check the peripheral id
     if (args[0].u_int != 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable);
     }
 
     // setup the object
@@ -445,7 +445,7 @@ STATIC mp_obj_t pyb_i2c_writeto(mp_uint_t n_args, const mp_obj_t *pos_args, mp_m
 
     // send the data
     if (!pyb_i2c_write(args[0].u_int, bufinfo.buf, bufinfo.len, args[2].u_bool)) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
     }
 
     // return the number of bytes written
@@ -514,7 +514,7 @@ STATIC mp_obj_t pyb_i2c_writeto_mem(mp_uint_t n_args, const mp_obj_t *pos_args,
         return mp_obj_new_int(bufinfo.len);
     }
 
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+    mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_i2c_writeto_mem_obj, 1, pyb_i2c_writeto_mem);
 
diff --git a/cc3200/mods/pybpin.c b/cc3200/mods/pybpin.c
index ce304404b..f59e65fc2 100644
--- a/cc3200/mods/pybpin.c
+++ b/cc3200/mods/pybpin.c
@@ -145,7 +145,7 @@ pin_obj_t *pin_find(mp_obj_t user_obj) {
         return pin_obj;
     }
 
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 
 void pin_config (pin_obj_t *self, int af, uint mode, uint pull, int value, uint strength) {
@@ -185,7 +185,7 @@ uint8_t pin_find_peripheral_unit (const mp_obj_t pin, uint8_t fn, uint8_t type)
             return pin_o->af_list[i].unit;
         }
     }
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 
 uint8_t pin_find_peripheral_type (const mp_obj_t pin, uint8_t fn, uint8_t unit) {
@@ -195,13 +195,13 @@ uint8_t pin_find_peripheral_type (const mp_obj_t pin, uint8_t fn, uint8_t unit)
             return pin_o->af_list[i].type;
         }
     }
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 
 int8_t pin_find_af_index (const pin_obj_t* pin, uint8_t fn, uint8_t unit, uint8_t type) {
     int8_t af = pin_obj_find_af(pin, fn, unit, type);
     if (af < 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
     return af;
 }
@@ -426,18 +426,18 @@ STATIC void pin_extint_register(pin_obj_t *self, uint32_t intmode, uint32_t prio
 STATIC void pin_validate_mode (uint mode) {
     if (mode != GPIO_DIR_MODE_IN && mode != GPIO_DIR_MODE_OUT && mode != PIN_TYPE_OD &&
         mode != GPIO_DIR_MODE_ALT && mode != GPIO_DIR_MODE_ALT_OD) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
 }
 STATIC void pin_validate_pull (uint pull) {
     if (pull != PIN_TYPE_STD && pull != PIN_TYPE_STD_PU && pull != PIN_TYPE_STD_PD) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
 }
 
 STATIC void pin_validate_drive(uint strength) {
     if (strength != PIN_STRENGTH_2MA && strength != PIN_STRENGTH_4MA && strength != PIN_STRENGTH_6MA) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
 }
 
@@ -450,7 +450,7 @@ STATIC void pin_validate_af(const pin_obj_t* pin, int8_t idx, uint8_t *fn, uint8
             return;
         }
     }
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 
 STATIC uint8_t pin_get_value (const pin_obj_t* self) {
@@ -591,7 +591,7 @@ STATIC mp_obj_t pin_obj_init_helper(pin_obj_t *self, mp_uint_t n_args, const mp_
     return mp_const_none;
 
 invalid_args:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 
 STATIC void pin_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
@@ -905,7 +905,7 @@ STATIC mp_obj_t pin_irq (mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *k
     return _irq;
 
 invalid_args:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pin_irq_obj, 1, pin_irq);
 
diff --git a/cc3200/mods/pybrtc.c b/cc3200/mods/pybrtc.c
index ea9941105..4662edbe7 100644
--- a/cc3200/mods/pybrtc.c
+++ b/cc3200/mods/pybrtc.c
@@ -202,7 +202,7 @@ STATIC uint pyb_rtc_datetime_s_us(const mp_obj_t datetime, uint32_t *seconds) {
 
     // verify the tuple
     if (len < 3 || len > 8) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
 
     tm.tm_year = mp_obj_get_int(items[0]);
@@ -294,7 +294,7 @@ STATIC mp_obj_t pyb_rtc_make_new(const mp_obj_type_t *type, mp_uint_t n_args, mp
 
     // check the peripheral id
     if (args[0].u_int != 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable);
     }
 
     // setup the object
@@ -362,7 +362,7 @@ STATIC mp_obj_t pyb_rtc_alarm (mp_uint_t n_args, const mp_obj_t *pos_args, mp_ma
 
     // check the alarm id
     if (args[0].u_int != 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable);
     }
 
     uint32_t f_seconds;
@@ -371,7 +371,7 @@ STATIC mp_obj_t pyb_rtc_alarm (mp_uint_t n_args, const mp_obj_t *pos_args, mp_ma
     if (MP_OBJ_IS_TYPE(args[1].u_obj, &mp_type_tuple)) { // datetime tuple given
         // repeat cannot be used with a datetime tuple
         if (repeat) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+            mp_raise_ValueError(mpexception_value_invalid_arguments);
         }
         f_mseconds = pyb_rtc_datetime_s_us (args[1].u_obj, &f_seconds) / 1000;
     } else { // then it must be an integer
@@ -397,7 +397,7 @@ STATIC mp_obj_t pyb_rtc_alarm_left (mp_uint_t n_args, const mp_obj_t *args) {
 
     // only alarm id 0 is available
     if (n_args > 1 && mp_obj_get_int(args[1]) != 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable);
     }
 
     // get the current time
@@ -415,7 +415,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_rtc_alarm_left_obj, 1, 2, pyb_rtc
 STATIC mp_obj_t pyb_rtc_alarm_cancel (mp_uint_t n_args, const mp_obj_t *args) {
     // only alarm id 0 is available
     if (n_args > 1 && mp_obj_get_int(args[1]) != 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable);
     }
     // disable the alarm
     pyb_rtc_disable_alarm();
@@ -453,7 +453,7 @@ STATIC mp_obj_t pyb_rtc_irq (mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_
     return _irq;
 
 invalid_args:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_rtc_irq_obj, 1, pyb_rtc_irq);
 
diff --git a/cc3200/mods/pybsd.c b/cc3200/mods/pybsd.c
index 55b797dc7..d7efbe872 100644
--- a/cc3200/mods/pybsd.c
+++ b/cc3200/mods/pybsd.c
@@ -107,7 +107,7 @@ STATIC mp_obj_t pyb_sd_init_helper (pybsd_obj_t *self, const mp_arg_val_t *args)
 
     pyb_sd_hw_init (self);
     if (sd_disk_init() != 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
     }
 
     // register it with the sleep module
@@ -132,7 +132,7 @@ STATIC mp_obj_t pyb_sd_make_new (const mp_obj_type_t *type, mp_uint_t n_args, mp
 
     // check the peripheral id
     if (args[0].u_int != 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable);
     }
 
     // setup and initialize the object
diff --git a/cc3200/mods/pybspi.c b/cc3200/mods/pybspi.c
index d4fcbe94b..5a040e3f5 100644
--- a/cc3200/mods/pybspi.c
+++ b/cc3200/mods/pybspi.c
@@ -131,7 +131,7 @@ STATIC void pybspi_rx (pyb_spi_obj_t *self, void *data) {
 
 STATIC void pybspi_transfer (pyb_spi_obj_t *self, const char *txdata, char *rxdata, uint32_t len, uint32_t *txchar) {
     if (!self->baudrate) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_request_not_possible);
     }
     // send and receive the data
     MAP_SPICSEnable(GSPI_BASE);
@@ -218,7 +218,7 @@ STATIC mp_obj_t pyb_spi_init_helper(pyb_spi_obj_t *self, const mp_arg_val_t *arg
     return mp_const_none;
 
 invalid_args:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 
 static const mp_arg_t pyb_spi_init_args[] = {
@@ -240,7 +240,7 @@ STATIC mp_obj_t pyb_spi_make_new(const mp_obj_type_t *type, mp_uint_t n_args, mp
 
     // check the peripheral id
     if (args[0].u_int != 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable);
     }
 
     // setup the object
@@ -295,7 +295,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_spi_write_obj, pyb_spi_write);
 STATIC mp_obj_t pyb_spi_read(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_nbytes,    MP_ARG_REQUIRED | MP_ARG_OBJ, },
-        { MP_QSTR_write,     MP_ARG_KW_ONLY  | MP_ARG_INT, {.u_int = 0x00} },
+        { MP_QSTR_write,     MP_ARG_INT, {.u_int = 0x00} },
     };
 
     // parse args
@@ -319,7 +319,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_spi_read_obj, 1, pyb_spi_read);
 STATIC mp_obj_t pyb_spi_readinto(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_buf,       MP_ARG_REQUIRED | MP_ARG_OBJ, },
-        { MP_QSTR_write,     MP_ARG_KW_ONLY  | MP_ARG_INT, {.u_int = 0x00} },
+        { MP_QSTR_write,     MP_ARG_INT, {.u_int = 0x00} },
     };
 
     // parse args
@@ -357,7 +357,7 @@ STATIC mp_obj_t pyb_spi_write_readinto (mp_obj_t self, mp_obj_t writebuf, mp_obj
         // get the read buffer
         mp_get_buffer_raise(readbuf, &bufinfo_read, MP_BUFFER_WRITE);
         if (bufinfo_read.len != bufinfo_write.len) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+            mp_raise_ValueError(mpexception_value_invalid_arguments);
         }
     }
 
diff --git a/cc3200/mods/pybtimer.c b/cc3200/mods/pybtimer.c
index 65fc7195e..2ac71cccb 100644
--- a/cc3200/mods/pybtimer.c
+++ b/cc3200/mods/pybtimer.c
@@ -223,7 +223,7 @@ STATIC uint32_t compute_prescaler_period_and_match_value(pyb_timer_channel_obj_t
     return prescaler;
 
 error:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 
 STATIC void timer_init (pyb_timer_obj_t *tim) {
@@ -319,7 +319,7 @@ STATIC mp_obj_t pyb_timer_init_helper(pyb_timer_obj_t *tim, mp_uint_t n_args, co
     return mp_const_none;
 
 error:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 
 STATIC mp_obj_t pyb_timer_make_new(const mp_obj_type_t *type, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args) {
@@ -329,7 +329,7 @@ STATIC mp_obj_t pyb_timer_make_new(const mp_obj_type_t *type, mp_uint_t n_args,
     // create a new Timer object
     int32_t timer_idx = mp_obj_get_int(args[0]);
     if (timer_idx < 0 || timer_idx > (PYBTIMER_NUM_TIMERS - 1)) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable);
     }
 
     pyb_timer_obj_t *tim = &pyb_timer_obj[timer_idx];
@@ -370,7 +370,7 @@ STATIC mp_obj_t pyb_timer_channel(mp_uint_t n_args, const mp_obj_t *pos_args, mp
 
     // verify that the timer has been already initialized
     if (!tim->config) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_request_not_possible);
     }
     if (channel_n != TIMER_A && channel_n != TIMER_B && channel_n != (TIMER_A | TIMER_B)) {
         // invalid channel
@@ -440,7 +440,7 @@ STATIC mp_obj_t pyb_timer_channel(mp_uint_t n_args, const mp_obj_t *pos_args, mp
     return ch;
 
 error:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_timer_channel_obj, 2, pyb_timer_channel);
 
@@ -560,7 +560,7 @@ STATIC mp_obj_t pyb_timer_channel_freq(mp_uint_t n_args, const mp_obj_t *args) {
         // set
         int32_t _frequency = mp_obj_get_int(args[1]);
         if (_frequency <= 0) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+            mp_raise_ValueError(mpexception_value_invalid_arguments);
         }
         ch->frequency = _frequency;
         ch->period = 1000000 / _frequency;
@@ -579,7 +579,7 @@ STATIC mp_obj_t pyb_timer_channel_period(mp_uint_t n_args, const mp_obj_t *args)
         // set
         int32_t _period = mp_obj_get_int(args[1]);
         if (_period <= 0) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+            mp_raise_ValueError(mpexception_value_invalid_arguments);
         }
         ch->period = _period;
         ch->frequency = 1000000 / _period;
@@ -712,7 +712,7 @@ STATIC mp_obj_t pyb_timer_channel_irq (mp_uint_t n_args, const mp_obj_t *pos_arg
     return _irq;
 
 invalid_args:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_timer_channel_irq_obj, 1, pyb_timer_channel_irq);
 
diff --git a/cc3200/mods/pybuart.c b/cc3200/mods/pybuart.c
index e7b5255bd..493522f83 100644
--- a/cc3200/mods/pybuart.c
+++ b/cc3200/mods/pybuart.c
@@ -280,7 +280,7 @@ STATIC void UARTGenericIntHandler(uint32_t uart_id) {
 STATIC void uart_check_init(pyb_uart_obj_t *self) {
     // not initialized
     if (!self->baudrate) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_request_not_possible);
     }
 }
 
@@ -432,7 +432,7 @@ STATIC mp_obj_t pyb_uart_init_helper(pyb_uart_obj_t *self, const mp_arg_val_t *a
     return mp_const_none;
 
 error:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 
 STATIC const mp_arg_t pyb_uart_init_args[] = {
@@ -472,7 +472,7 @@ STATIC mp_obj_t pyb_uart_make_new(const mp_obj_type_t *type, mp_uint_t n_args, m
     }
 
     if (uart_id > PYB_UART_1) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable);
     }
 
     // get the correct uart instance
@@ -556,7 +556,7 @@ STATIC mp_obj_t pyb_uart_irq (mp_uint_t n_args, const mp_obj_t *pos_args, mp_map
     return uart_irq_new (self, trigger, priority, args[2].u_obj);
 
 invalid_args:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+    mp_raise_ValueError(mpexception_value_invalid_arguments);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_uart_irq_obj, 1, pyb_uart_irq);
 
@@ -622,7 +622,7 @@ STATIC mp_uint_t pyb_uart_write(mp_obj_t self_in, const void *buf_in, mp_uint_t
 
     // write the data
     if (!uart_tx_strn(self, buf, size)) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_operation_failed));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_operation_failed);
     }
     return size;
 }
diff --git a/cc3200/mods/pybwdt.c b/cc3200/mods/pybwdt.c
index 6e5fe4714..30478c83c 100644
--- a/cc3200/mods/pybwdt.c
+++ b/cc3200/mods/pybwdt.c
@@ -100,14 +100,14 @@ STATIC mp_obj_t pyb_wdt_make_new(const mp_obj_type_t *type, mp_uint_t n_args, mp
     mp_arg_parse_all(n_args, all_args, &kw_args, MP_ARRAY_SIZE(args), pyb_wdt_init_args, args);
 
     if (args[0].u_obj != mp_const_none && mp_obj_get_int(args[0].u_obj) > 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_resource_not_avaliable);
     }
     uint timeout_ms = args[1].u_int;
     if (timeout_ms < PYBWDT_MIN_TIMEOUT_MS) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
     if (pyb_wdt_obj.running) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, mpexception_os_request_not_possible));
+        mp_raise_msg(&mp_type_OSError, mpexception_os_request_not_possible);
     }
 
     // Enable the WDT peripheral clock
diff --git a/cc3200/mpconfigport.h b/cc3200/mpconfigport.h
index 0b16d730d..bf3e691bd 100644
--- a/cc3200/mpconfigport.h
+++ b/cc3200/mpconfigport.h
@@ -38,6 +38,7 @@
 // options to control how Micro Python is built
 
 #define MICROPY_ALLOC_PATH_MAX                      (128)
+#define MICROPY_PERSISTENT_CODE_LOAD                (1)
 #define MICROPY_EMIT_THUMB                          (0)
 #define MICROPY_EMIT_INLINE_THUMB                   (0)
 #define MICROPY_COMP_MODULE_CONST                   (1)
diff --git a/cc3200/mpthreadport.c b/cc3200/mpthreadport.c
index 064aa6ba1..e77ac4ae5 100644
--- a/cc3200/mpthreadport.c
+++ b/cc3200/mpthreadport.c
@@ -28,10 +28,13 @@
 
 #include "py/mpconfig.h"
 #include "py/mpstate.h"
+#include "py/runtime.h"
 #include "py/gc.h"
 #include "py/mpthread.h"
+#include "py/mphal.h"
 #include "mptask.h"
 #include "task.h"
+#include "irq.h"
 
 #if MICROPY_PY_THREAD
 
@@ -131,7 +134,7 @@ void mp_thread_create(void *(*entry)(void*), void *arg, size_t *stack_size) {
     TaskHandle_t id = xTaskCreateStatic(freertos_entry, "Thread", *stack_size / sizeof(void*), arg, 2, stack, tcb);
     if (id == NULL) {
         mp_thread_mutex_unlock(&thread_mutex);
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "can't create thread"));
+        mp_raise_msg(&mp_type_OSError, "can't create thread");
     }
 
     // add thread to linked list of all threads
@@ -165,14 +168,23 @@ void mp_thread_mutex_init(mp_thread_mutex_t *mutex) {
     mutex->handle = xSemaphoreCreateMutexStatic(&mutex->buffer);
 }
 
+// To allow hard interrupts to work with threading we only take/give the semaphore
+// if we are not within an interrupt context and interrupts are enabled.
+
 int mp_thread_mutex_lock(mp_thread_mutex_t *mutex, int wait) {
-    int ret = xSemaphoreTake(mutex->handle, wait ? portMAX_DELAY : 0);
-    return ret == pdTRUE;
+    if ((HAL_NVIC_INT_CTRL_REG & HAL_VECTACTIVE_MASK) == 0 && query_irq() == IRQ_STATE_ENABLED) {
+        int ret = xSemaphoreTake(mutex->handle, wait ? portMAX_DELAY : 0);
+        return ret == pdTRUE;
+    } else {
+        return 1;
+    }
 }
 
 void mp_thread_mutex_unlock(mp_thread_mutex_t *mutex) {
-    xSemaphoreGive(mutex->handle);
-    // TODO check return value
+    if ((HAL_NVIC_INT_CTRL_REG & HAL_VECTACTIVE_MASK) == 0 && query_irq() == IRQ_STATE_ENABLED) {
+        xSemaphoreGive(mutex->handle);
+        // TODO check return value
+    }
 }
 
 #endif // MICROPY_PY_THREAD
diff --git a/cc3200/serverstask.c b/cc3200/serverstask.c
index 1305afda0..6b5899e18 100644
--- a/cc3200/serverstask.c
+++ b/cc3200/serverstask.c
@@ -29,7 +29,7 @@
 
 #include "py/mpconfig.h"
 #include "py/misc.h"
-#include "py/nlr.h"
+#include "py/runtime.h"
 #include "py/mphal.h"
 #include "serverstask.h"
 #include "simplelink.h"
@@ -187,7 +187,7 @@ void servers_close_socket (int16_t *sd) {
 
 void servers_set_login (char *user, char *pass) {
     if (strlen(user) > SERVERS_USER_PASS_LEN_MAX || strlen(pass) > SERVERS_USER_PASS_LEN_MAX) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
     memcpy(servers_user, user, SERVERS_USER_PASS_LEN_MAX);
     memcpy(servers_pass, pass, SERVERS_USER_PASS_LEN_MAX);
@@ -196,7 +196,7 @@ void servers_set_login (char *user, char *pass) {
 void servers_set_timeout (uint32_t timeout) {
     if (timeout < SERVERS_MIN_TIMEOUT_MS) {
         // timeout is too low
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, mpexception_value_invalid_arguments));
+        mp_raise_ValueError(mpexception_value_invalid_arguments);
     }
     servers_data.timeout = timeout;
 }
diff --git a/conf.py b/conf.py
index 47dc20f59..bb2a2d897 100644
--- a/conf.py
+++ b/conf.py
@@ -69,7 +69,7 @@ copyright = '2014-2016, Damien P. George, Scott Shawcroft, Tony DiCola and other
 # The short X.Y version.
 version = '1.8'
 # The full version, including alpha/beta/rc tags.
-release = '1.8.4'
+release = '1.8.5'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
diff --git a/docs/library/machine.SPI.rst b/docs/library/machine.SPI.rst
index 73b3a3996..9b4d62e01 100644
--- a/docs/library/machine.SPI.rst
+++ b/docs/library/machine.SPI.rst
@@ -1,10 +1,13 @@
 .. currentmodule:: machine
 
-class SPI -- a master-driven serial protocol
-============================================
+class SPI -- a Serial Peripheral Interface bus protocol
+=======================================================
 
-SPI is a serial protocol that is driven by a master.  At the physical level
-there are 3 lines: SCK, MOSI, MISO.
+SPI is a serial protocol that is driven by a master.  At the physical level,
+bus consistens of 3 lines: SCK, MOSI, MISO. Multiple devices can share the
+same bus. Each device should have a separate, 4th signal, SS (Slave Select),
+to select a particualr device on a bus with which communication takes place.
+Management of an SS signal should happen in user code (via machine.Pin class).
 
 .. only:: port_wipy
 
@@ -21,65 +24,83 @@ there are 3 lines: SCK, MOSI, MISO.
 Constructors
 ------------
 
-.. only:: port_wipy
+.. class:: SPI(id, ...)
 
-    .. class:: SPI(id, ...)
+   Construct an SPI object on the given bus, ``id``. Values of ``id`` depend
+   on a particular port and its hardware. Values 0, 1, etc. are commonly used
+   to select hardware SPI block #0, #1, etc. Value -1 can be used for
+   bitbanging (software) implementation of SPI (if supported by a port).
 
-       Construct an SPI object on the given bus.  ``id`` can be only 0.
-       With no additional parameters, the SPI object is created but not
-       initialised (it has the settings from the last initialisation of
-       the bus, if any).  If extra arguments are given, the bus is initialised.
-       See ``init`` for parameters of initialisation.
+   With no additional parameters, the SPI object is created but not
+   initialised (it has the settings from the last initialisation of
+   the bus, if any).  If extra arguments are given, the bus is initialised.
+   See ``init`` for parameters of initialisation.
 
 Methods
 -------
 
-.. method:: SPI.init(mode, baudrate=1000000, \*, polarity=0, phase=0, bits=8, firstbit=SPI.MSB, pins=(CLK, MOSI, MISO))
+.. method:: SPI.init(baudrate=1000000, \*, polarity=0, phase=0, bits=8, firstbit=SPI.MSB, pins=(CLK, MOSI, MISO), sck=None, mosi=None, miso=None)
 
    Initialise the SPI bus with the given parameters:
 
-     - ``mode`` must be ``SPI.MASTER``.
      - ``baudrate`` is the SCK clock rate.
      - ``polarity`` can be 0 or 1, and is the level the idle clock line sits at.
      - ``phase`` can be 0 or 1 to sample data on the first or second clock edge
        respectively.
-     - ``bits`` is the width of each transfer, accepted values are 8, 16 and 32.
-     - ``firstbit`` can be ``SPI.MSB`` only.
-     - ``pins`` is an optional tuple with the pins to assign to the SPI bus.
+     - ``bits`` is the width in bits of each transfer. Only 8 of is guaranteed to be supported by all hardware.
+     - ``firstbit`` can be ``SPI.MSB`` or ``SPI.LSB``.
+     - ``pins`` is an optional tuple with the pins to assign to the SPI bus (deprecated, only for WiPy).
+     - ``sck``, ``mosi``, ``miso`` are pins (machine.Pin) objects to use for bus signals. For most
+       hardware SPI blocks (as selected by ``id`` parameter to the constructore), pins are fixed
+       and cannot be changed. In some cases, hardware blocks allow 2-3 alternative pin sets for
+       a hardware SPI block. Arbitrary pin assignments are possible only for a bitbanging SPI driver
+       (``id``=-1).
 
 .. method:: SPI.deinit()
 
    Turn off the SPI bus.
 
-.. method:: SPI.write(buf)
+.. method:: SPI.read(nbytes, write=0x00)
+
+    Read a number of bytes specified by ``nbytes`` while continuously writing
+    the single byte given by ``write``.
+    Returns a ``bytes`` object with the data that was read.
+
+.. method:: SPI.readinto(buf, write=0x00)
 
-    Write the data contained in ``buf``. 
-    Returns the number of bytes written.
+    Read into the buffer specified by ``buf`` while continuously writing the
+    single byte given by ``write``.
+    Returns ``None``.
 
-.. method:: SPI.read(nbytes, *, write=0x00)
+    Note: on WiPy this function returns the number of bytes read.
 
-    Read the ``nbytes`` while writing the data specified by ``write``.
-    Return the number of bytes read.
+.. method:: SPI.write(buf)
 
-.. method:: SPI.readinto(buf, *, write=0x00)
+    Write the bytes contained in ``buf``.
+    Returns ``None``.
 
-    Read into the buffer specified by ``buf`` while writing the data specified by
-    ``write``.
-    Return the number of bytes read.
+    Note: on WiPy this function returns the number of bytes written.
 
 .. method:: SPI.write_readinto(write_buf, read_buf)
 
-    Write from ``write_buf`` and read into ``read_buf``. Both buffers must have the
+    Write the bytes from ``write_buf`` while reading into ``read_buf``.  The
+    buffers can be the same or different, but both buffers must have the
     same length.
-    Returns the number of bytes written
+    Returns ``None``.
+
+    Note: on WiPy this function returns the number of bytes written.
 
 Constants
 ---------
 
 .. data:: SPI.MASTER
 
-   for initialising the SPI bus to master
+   for initialising the SPI bus to master; this is only used for the WiPy
 
 .. data:: SPI.MSB
 
    set the first bit to be the most significant bit
+
+.. data:: SPI.LSB
+
+   set the first bit to be the least significant bit
diff --git a/docs/reference/constrained.rst b/docs/reference/constrained.rst
new file mode 100644
index 000000000..7c1b6a3eb
--- /dev/null
+++ b/docs/reference/constrained.rst
@@ -0,0 +1,456 @@
+.. _constrained:
+
+MicroPython on Microcontrollers
+===============================
+
+MicroPython is designed to be capable of running on microcontrollers. These
+have hardware limitations which may be unfamiliar to programmers more familiar
+with conventional computers. In particular the amount of RAM and nonvolatile
+"disk" (flash memory) storage is limited. This tutorial offers ways to make
+the most of the limited resources. Because MicroPython runs on controllers
+based on a variety of architectures, the methods presented are generic: in some
+cases it will be necessary to obtain detailed information from platform specific
+documentation.
+
+Flash Memory
+------------
+
+On the Pyboard the simple way to address the limited capacity is to fit a micro
+SD card. In some cases this is impractical, either because the device does not
+have an SD card slot or for reasons of cost or power consumption; hence the
+on-chip flash must be used. The firmware including the MicroPython subsystem is
+stored in the onboard flash. The remaining capacity is available for use. For
+reasons connected with the physical architecture of the flash memory part of
+this capacity may be inaccessible as a filesystem. In such cases this space may
+be employed by incorporating user modules into a firmware build which is then
+flashed to the device.
+
+There are two ways to achieve this: frozen modules and frozen bytecode. Frozen
+modules store the Python source with the firmware. Frozen bytecode uses the
+cross compiler to convert the source to bytecode which is then stored with the
+firmware. In either case the module may be accessed with an import statement:
+
+.. code::
+
+    import mymodule
+
+The procedure for producing frozen modules and bytecode is platform dependent;
+instructions for building the firmware can be found in the README files in the
+relevant part of the source tree.
+
+In general terms the steps are as follows:
+
+* Clone the MicroPython `repository <https://github.com/micropython/micropython>`_.
+* Acquire the (platform specific) toolchain to build the firmware.
+* Build the cross compiler.
+* Place the modules to be frozen in a specified directory (dependent on whether
+  the module is to be frozen as source or as bytecode).
+* Build the firmware. A specific command may be required to build frozen
+  code of either type - see the platform documentation.
+* Flash the firmware to the device.
+
+RAM
+---
+
+When reducing RAM usage there are two phases to consider: compilation and
+execution. In addition to memory consumption, there is also an issue known as
+heap fragmentation. In general terms it is best to minimise the repeated
+creation and destruction of objects. The reason for this is covered in the
+section covering the `heap`_.
+
+Compilation Phase
+~~~~~~~~~~~~~~~~~
+
+When a module is imported, MicroPython compiles the code to bytecode which is
+then executed by the MicroPython virtual machine (VM). The bytecode is stored
+in RAM. The compiler itself requires RAM, but this becomes available for use
+when the compilation has completed.
+
+If a number of modules have already been imported the situation can arise where
+there is insufficient RAM to run the compiler. In this case the import
+statement will produce a memory exception.
+
+If a module instantiates global objects on import it will consume RAM at the
+time of import, which is then unavailable for the compiler to use on subsequent
+imports. In general it is best to avoid code which runs on import; a better
+approach is to have initialisation code which is run by the application after
+all modules have been imported. This maximises the RAM available to the
+compiler.
+
+If RAM is still insufficient to compile all modules one solution is to
+precompile modules. MicroPython has a cross compiler capable of compiling Python
+modules to bytecode (see the README in the mpy-cross directory). The resulting
+bytecode file has a .mpy extension; it may be copied to the filesystem and
+imported in the usual way. Alternatively some or all modules may be implemented
+as frozen bytecode: on most platforms this saves even more RAM as the bytecode
+is run directly from flash rather than being stored in RAM.
+
+Execution Phase
+~~~~~~~~~~~~~~~
+
+There are a number of coding techniques for reducing RAM usage.
+
+**Constants**
+
+MicroPython provides a ``const`` keyword which may be used as follows:
+
+.. code::
+
+    from micropython import const
+    ROWS = const(33)
+    _COLS = const(0x10)
+    a = ROWS
+    b = _COLS
+
+In both instances where the constant is assigned to a variable the compiler
+will avoid coding a lookup to the name of the constant by substituting its
+literal value. This saves bytecode and hence RAM. However the ``ROWS`` value
+will occupy at least two machine words, one each for the key and value in the
+globals dictionary. The presence in the dictionary is necessary because another
+module might import or use it. This RAM can be saved by prepending the name
+with an underscore as in ``_COLS``: this symbol is not visible outside the
+module so will not occupy RAM.
+
+The argument to ``const()`` may be anything which, at compile time, evaluates
+to an integer e.g. ``0x100`` or ``1 << 8``. It can even include other const
+symbols that have already been defined, e.g. ``1 << BIT``.
+
+**Constant data structures**
+
+Where there is a substantial volume of constant data and the platform supports
+execution from Flash, RAM may be saved as follows. The data should be located in
+Python modules and frozen as bytecode. The data must be defined as ``bytes``
+objects. The compiler 'knows' that ``bytes`` objects are immutable and ensures
+that the objects remain in flash memory rather than being copied to RAM. The
+``ustruct`` module can assist in converting between ``bytes`` types and other
+Python built-in types.
+
+When considering the implications of frozen bytecode, note that in Python
+strings, floats, bytes, integers and complex numbers are immutable. Accordingly
+these will be frozen into flash. Thus, in the line
+
+.. code::
+
+    mystring = "The quick brown fox"
+
+the actual string "The quick brown fox" will reside in flash. At runtime a
+reference to the string is assigned to the *variable* ``mystring``. The reference
+occupies a single machine word. In principle a long integer could be used to
+store constant data:
+
+.. code::
+
+    bar = 0xDEADBEEF0000DEADBEEF
+
+As in the string example, at runtime a reference to the arbitrarily large
+integer is assigned to the variable ``bar``. That reference occupies a
+single machine word. 
+
+It might be expected that tuples of integers could be employed for the purpose
+of storing constant data with minimal RAM use. With the current compiler this
+is ineffective (the code works, but RAM is not saved).
+
+.. code::
+
+    foo = (1, 2, 3, 4, 5, 6, 100000)
+
+At runtime the tuple will be located in RAM. This may be subject to future
+improvement.
+
+**Needless object creation**
+
+There are a number of situations where objects may unwittingly be created and
+destroyed. This can reduce the usability of RAM through fragmentation. The
+following sections discuss instances of this.
+
+**String concatenation**
+
+Consider the following code fragments which aim to produce constant strings:
+
+.. code::
+
+    var = "foo" + "bar"
+    var1 = "foo" "bar"
+    var2 = """\
+    foo\
+    bar"""
+
+Each produces the same outcome, however the first needlessly creates two string
+objects at runtime, allocates more RAM for concatenation before producing the
+third. The others perform the concatenation at compile time which is more
+efficient, reducing fragmentation.
+
+Where strings must be dynamically created before being fed to a stream such as
+a file it will save RAM if this is done in a piecemeal fashion. Rather than
+creating a large string object, create a substring and feed it to the stream
+before dealing with the next.
+
+The best way to create dynamic strings is by means of the string ``format``
+method:
+
+.. code::
+
+    var = "Temperature {:5.2f} Pressure {:06d}\n".format(temp, press)
+
+**Buffers**
+
+When accessing devices such as instances of UART, I2C and SPI interfaces, using
+pre-allocated buffers avoids the creation of needless objects. Consider these
+two loops:
+
+.. code::
+
+    while True:
+        var = spi.read(100)
+        # process data
+
+    buf = bytearray(100)
+    while True:
+        spi.readinto(buf)
+        # process data in buf
+
+The first creates a buffer on each pass whereas the second re-uses a pre-allocated
+buffer; this is both faster and more efficient in terms of memory fragmentation.
+
+**Bytes are smaller than ints**
+
+On most platforms an integer consumes four bytes. Consider the two calls to the
+function ``foo()``:
+
+.. code::
+
+    def foo(bar):
+        for x in bar:
+            print(x)
+    foo((1, 2, 0xff))
+    foo(b'\1\2\xff')
+
+In the first call a tuple of integers is created in RAM. The second efficiently
+creates a ``bytes`` object consuming the minimum amount of RAM. If the module
+were frozen as bytecode, the ``bytes`` object would reside in flash.
+
+**Strings Versus Bytes**
+
+Python3 introduced Unicode support. This introduced a distinction between a
+string and an array of bytes. MicroPython ensures that Unicode strings take no
+additional space so long as all characters in the string are ASCII (i.e. have
+a value < 126). If values in the full 8-bit range are required ``bytes`` and
+``bytearray`` objects can be used to ensure that no additional space will be
+required. Note that most string methods (e.g. ``strip()``) apply also to ``bytes``
+instances so the process of eliminating Unicode can be painless.
+
+.. code::
+
+    s = 'the quick brown fox'  # A string instance
+    b = b'the quick brown fox'  # a bytes instance
+
+Where it is necessary to convert between strings and bytes the string ``encode``
+and the bytes ``decode`` methods can be used. Note that both strings and bytes
+are immutable. Any operation which takes as input such an object and produces
+another implies at least one RAM allocation to produce the result. In the
+second line below a new bytes object is allocated. This would also occur if ``foo``
+were a string.
+
+.. code::
+
+    foo = b'   empty whitespace'
+    foo = foo.lstrip()
+
+**Runtime compiler execution**
+
+The Python keywords ``eval`` and ``exec`` invoke the compiler at runtime, which
+requires significant amounts of RAM. Note that the ``pickle`` library employs
+``exec``. It may be more RAM efficient to use the ``json`` library for object
+serialisation.
+
+**Storing strings in flash**
+
+Python strings are immutable hence have the potential to be stored in read only
+memory. The compiler can place in flash strings defined in Python code. As with
+frozen modules it is necessary to have a copy of the source tree on the PC and
+the toolchain to build the firmware. The procedure will work even if the
+modules have not been fully debugged, so long as they can be imported and run.
+
+After importing the modules, execute:
+
+.. code::
+
+    micropython.qstr_info(1)
+
+Then copy and paste all the Q(xxx) lines into a text editor. Check for and
+remove lines which are obviously invalid. Open the file qstrdefsport.h which
+will be found in stmhal (or the equivalent directory for the architecture in
+use). Copy and paste the corrected lines at the end of the file. Save the file,
+rebuild and flash the firmware. The outcome can be checked by importing the
+modules and again issuing:
+
+.. code::
+
+    micropython.qstr_info(1)
+
+The Q(xxx) lines should be gone.
+
+.. _heap:
+
+The Heap
+--------
+
+When a running program instantiates an object the necessary RAM is allocated
+from a fixed size pool known as the heap. When the object goes out of scope (in
+other words becomes inaccessible to code) the redundant object is known as
+"garbage". A process known as "garbage collection" (GC) reclaims that memory,
+returning it to the free heap. This process runs automatically, however it can
+be invoked directly by issuing ``gc.collect()``.
+
+The discourse on this is somewhat involved. For a 'quick fix' issue the
+following periodically:
+
+.. code::
+
+    gc.collect()
+    gc.threshold(gc.mem_free() // 4 + gc.mem_alloc())
+
+Fragmentation
+~~~~~~~~~~~~~
+
+Say a program creates an object ``foo``, then an object ``bar``. Subsequently
+``foo`` goes out of scope but ``bar`` remains. The RAM used by ``foo`` will be
+reclaimed by GC. However if ``bar`` was allocated to a higher address, the
+RAM reclaimed from ``foo`` will only be of use for objects no bigger than
+``foo``. In a complex or long running program the heap can become fragmented:
+despite there being a substantial amount of RAM available, there is insufficient
+contiguous space to allocate a particular object, and the program fails with a
+memory error.
+
+The techniques outlined above aim to minimise this. Where large permanent buffers
+or other objects are required it is best to instantiate these early in the
+process of program execution before fragmentation can occur. Further improvements
+may be made by monitoring the state of the heap and by controlling GC; these are
+outlined below.
+
+Reporting
+~~~~~~~~~
+
+A number of library functions are available to report on memory allocation and
+to control GC. These are to be found in the ``gc`` and ``micropython`` modules.
+The following example may be pasted at the REPL (``ctrl e`` to enter paste mode,
+``ctrl d`` to run it).
+
+.. code::
+
+    import gc
+    import micropython
+    gc.collect()
+    micropython.mem_info()
+    print('-----------------------------')
+    print('Initial free: {} allocated: {}'.format(gc.mem_free(), gc.mem_alloc()))
+    def func():
+        a = bytearray(10000)
+    gc.collect()
+    print('Func definition: {} allocated: {}'.format(gc.mem_free(), gc.mem_alloc()))
+    func()
+    print('Func run free: {} allocated: {}'.format(gc.mem_free(), gc.mem_alloc()))
+    gc.collect()
+    print('Garbage collect free: {} allocated: {}'.format(gc.mem_free(), gc.mem_alloc()))
+    print('-----------------------------')
+    micropython.mem_info(1)
+
+Methods employed above:
+
+* ``gc.collect()`` Force a garbage collection. See footnote.
+* ``micropython.mem_info()`` Print a summary of RAM utilisation.
+* ``gc.mem_free()`` Return the free heap size in bytes.
+* ``gc.mem_alloc()`` Return the number of bytes currently allocated.
+* ``micropython.mem_info(1)`` Print a table of heap utilisation (detailed below).
+
+The numbers produced are dependent on the platform, but it can be seen that
+declaring the function uses a small amount of RAM in the form of bytecode
+emitted by the compiler (the RAM used by the compiler has been reclaimed).
+Running the function uses over 10KiB, but on return ``a`` is garbage because it
+is out of scope and cannot be referenced. The final ``gc.collect()`` recovers
+that memory.
+
+The final output produced by ``micropython.mem_info(1)`` will vary in detail but
+may be interpreted as follows:
+
+====== =================
+Symbol Meaning
+====== =================
+   .   free block
+   h   head block
+   =   tail block
+   m   marked head block
+   T   tuple
+   L   list
+   D   dict
+   F   float
+   B   byte code
+   M   module
+====== =================
+
+Each letter represents a single block of memory, a block being 16 bytes. So each
+line of the heap dump represents 0x400 bytes or 1KiB of RAM.
+
+Control of Garbage Collection
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A GC can be demanded at any time by issuing ``gc.collect()``. It is advantageous
+to do this at intervals, firstly to pre-empt fragmentation and secondly for
+performance. A GC can take several milliseconds but is quicker when there is
+little work to do (about 1ms on the Pyboard). An explicit call can minimise that
+delay while ensuring it occurs at points in the program when it is acceptable.
+
+Automatic GC is provoked under the following circumstances. When an attempt at
+allocation fails, a GC is performed and the allocation re-tried. Only if this
+fails is an exception raised. Secondly an automatic GC will be triggered if the
+amount of free RAM falls below a threshold. This threshold can be adapted as
+execution progresses:
+
+.. code::
+
+    gc.collect()
+    gc.threshold(gc.mem_free() // 4 + gc.mem_alloc())
+
+This will provoke a GC when more than 25% of the currently free heap becomes
+occupied.
+
+In general modules should instantiate data objects at runtime using constructors
+or other initialisation functions. The reason is that if this occurs on
+initialisation the compiler may be starved of RAM when subsequent modules are
+imported. If modules do instantiate data on import then ``gc.collect()`` issued
+after the import will ameliorate the problem.
+
+String Operations
+-----------------
+
+MicroPython handles strings in an efficient manner and understanding this can
+help in designing applications to run on microcontrollers. When a module
+is compiled, strings which occur multiple times are stored once only, a process
+known as string interning. In MicroPython an interned string is known as a ``qstr``.
+In a module imported normally that single instance will be located in RAM, but
+as described above, in modules frozen as bytecode it will be located in flash.
+
+String comparisons are also performed efficiently using hashing rather than
+character by character. The penalty for using strings rather than integers may
+hence be small both in terms of performance and RAM usage - a fact which may
+come as a surprise to C programmers.
+
+Postscript
+----------
+
+MicroPython passes, returns and (by default) copies objects by reference. A
+reference occupies a single machine word so these processes are efficient in
+RAM usage and speed.
+
+Where variables are required whose size is neither a byte nor a machine word
+there are standard libraries which can assist in storing these efficiently and
+in performing conversions. See the ``array``, ``ustruct`` and ``uctypes``
+modules.
+
+Footnote: gc.collect() return value
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+On Unix and Windows platforms the ``gc.collect()`` method returns an integer
+which signifies the number of distinct memory regions that were reclaimed in the
+collection (more precisely, the number of heads that were turned into frees). For
+efficiency reasons bare metal ports do not return this value.
diff --git a/docs/reference/index.rst b/docs/reference/index.rst
index ae8d6530a..7a85fc5cf 100644
--- a/docs/reference/index.rst
+++ b/docs/reference/index.rst
@@ -15,6 +15,7 @@ MicroPython are described in the sections here.
    repl.rst
    isr_rules.rst
    speed_python.rst
+   constrained.rst
 
 .. only:: port_pyboard
 
diff --git a/esp8266/Makefile b/esp8266/Makefile
index d86fec180..5f0044df0 100644
--- a/esp8266/Makefile
+++ b/esp8266/Makefile
@@ -7,19 +7,19 @@ MICROPY_PY_USSL = 1
 MICROPY_SSL_AXTLS = 1
 MICROPY_PY_BTREE = 1
 
+FROZEN_DIR = scripts
+FROZEN_MPY_DIR = modules
+
 # include py core make definitions
 include ../py/py.mk
 
 MPY_CROSS = ../mpy-cross/mpy-cross
 MPY_TOOL = ../tools/mpy-tool.py
-MAKE_FROZEN = ../tools/make-frozen.py
 
-FROZEN_DIR = scripts
-FROZEN_MPY_DIR = modules
 PORT ?= /dev/ttyACM0
 BAUD ?= 115200
 FLASH_MODE ?= qio
-FLASH_SIZE ?= 8m
+FLASH_SIZE ?= detect
 CROSS_COMPILE = xtensa-lx106-elf-
 ESP_SDK = $(shell $(CC) -print-sysroot)/usr
 
@@ -66,6 +66,7 @@ SRC_C = \
 	main.c \
 	help.c \
 	esp_mphal.c \
+	esp_init_data.c \
 	gccollect.c \
 	lexerstr32.c \
 	uart.c \
@@ -90,7 +91,6 @@ SRC_C = \
 	modmachine.c \
 	modonewire.c \
 	ets_alt_task.c \
-	$(BUILD)/frozen.c \
 	fatfs_port.c \
 	axtls_helpers.c \
 	hspi.c \
diff --git a/esp8266/esp8266.ld b/esp8266/esp8266.ld
index c726790d3..5fb6f1379 100644
--- a/esp8266/esp8266.ld
+++ b/esp8266/esp8266.ld
@@ -20,7 +20,7 @@ PHDRS
     irom0_0_phdr PT_LOAD;
 }
 
-ENTRY(call_user_start)
+ENTRY(firmware_start)
 EXTERN(_DebugExceptionVector)
 EXTERN(_DoubleExceptionVector)
 EXTERN(_KernelExceptionVector)
@@ -130,8 +130,10 @@ SECTIONS
 
         *stmhal/pybstdio.o(.literal*, .text*)
 
+        build/main.o(.literal* .text*)
         *gccollect.o(.literal* .text*)
         *gchelper.o(.literal* .text*)
+        *help.o(.literal* .text*)
         *lexerstr32.o(.literal* .text*)
         *utils.o(.literal* .text*)
         *modpyb.o(.literal*, .text*)
@@ -141,6 +143,7 @@ SECTIONS
         *modpybadc.o(.literal*, .text*)
         *modpybuart.o(.literal*, .text*)
         *modpybi2c.o(.literal*, .text*)
+        *modmachine.o(.literal*, .text*)
         *modmachinewdt.o(.literal*, .text*)
         *modpybspi.o(.literal*, .text*)
         *modpybhspi.o(.literal*, .text*)
@@ -199,7 +202,8 @@ SECTIONS
         *(.entry.text)
         *(.init.literal)
         *(.init)
-        *(.literal .text .literal.* .text.* .stub .gnu.warning .gnu.linkonce.literal.* .gnu.linkonce.t.*.literal .gnu.linkonce.t.*)
+        *(.literal .text .literal.* .text.* .iram0.literal .iram0.text .iram0.text.*.literal .iram0.text.*)
+        *(.stub .gnu.warning .gnu.linkonce.literal.* .gnu.linkonce.t.*.literal .gnu.linkonce.t.*)
         *(.fini.literal)
         *(.fini)
         *(.gnu.version)
diff --git a/esp8266/esp_init_data.c b/esp8266/esp_init_data.c
new file mode 100644
index 000000000..b229f751d
--- /dev/null
+++ b/esp8266/esp_init_data.c
@@ -0,0 +1,80 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Paul Sokolovsky
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdio.h>
+#include "ets_sys.h"
+#include "etshal.h"
+#include "esp_mphal.h"
+#include "user_interface.h"
+#include "extmod/misc.h"
+
+uint32_t SPIRead(uint32_t offset, void *buf, uint32_t len);
+uint32_t SPIWrite(uint32_t offset, const void *buf, uint32_t len);
+uint32_t SPIEraseSector(int sector);
+NORETURN void call_user_start(void);
+void ets_printf(const char *fmt, ...);
+extern char flashchip;
+
+static const uint8_t default_init_data[] __attribute__((aligned(4))) = {
+0x05, 0x00, 0x04, 0x02, 0x05, 0x05, 0x05, 0x02, 0x05, 0x00, 0x04, 0x05, 0x05, 0x04, 0x05, 0x05,
+0x04, 0xfe, 0xfd, 0xff, 0xf0, 0xf0, 0xf0, 0xe0, 0xe0, 0xe0, 0xe1, 0x0a, 0xff, 0xff, 0xf8, 0x00,
+0xf8, 0xf8, 0x52, 0x4e, 0x4a, 0x44, 0x40, 0x38, 0x00, 0x00, 0x01, 0x01, 0x02, 0x03, 0x04, 0x05,
+0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+0xe1, 0x0a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x93, 0x43, 0x00, 0x00, 0x00,
+0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+};
+
+void firmware_start(void) {
+    // For SDK 1.5.2, either address has shifted and not mirrored in
+    // eagle.rom.addr.v6.ld, or extra initial member was added.
+    SpiFlashChip *flash = (SpiFlashChip*)(&flashchip + 4);
+
+    char buf[128];
+    SPIRead(flash->chip_size - 4 * 0x1000, buf, sizeof(buf));
+    /*for (int i = 0; i < sizeof(buf); i++) {
+        static char hexf[] = "%x ";
+        ets_printf(hexf, buf[i]);
+    }*/
+
+    bool inited = false;
+    for (int i = 0; i < sizeof(buf); i++) {
+        if (buf[i] != 0xff) {
+            inited = true;
+            break;
+        }
+    }
+
+    if (!inited) {
+        static char msg[] = "Writing init data\n";
+        ets_printf(msg);
+        SPIRead((uint32_t)&default_init_data - 0x40200000, buf, sizeof(buf));
+        SPIWrite(flash->chip_size - 4 * 0x1000, buf, sizeof(buf));
+    }
+
+    asm("j call_user_start");
+}
diff --git a/esp8266/main.c b/esp8266/main.c
index c938dcb30..033ab7afe 100644
--- a/esp8266/main.c
+++ b/esp8266/main.c
@@ -141,7 +141,7 @@ mp_obj_t mp_builtin_open(uint n_args, const mp_obj_t *args, mp_map_t *kwargs) {
 }
 MP_DEFINE_CONST_FUN_OBJ_KW(mp_builtin_open_obj, 1, mp_builtin_open);
 
-void nlr_jump_fail(void *val) {
+void MP_FASTCODE(nlr_jump_fail)(void *val) {
     printf("NLR jump failed\n");
     for (;;) {
     }
diff --git a/esp8266/modules/webrepl.py b/esp8266/modules/webrepl.py
index da3e70c59..b200f4fc8 100644
--- a/esp8266/modules/webrepl.py
+++ b/esp8266/modules/webrepl.py
@@ -31,6 +31,10 @@ def setup_conn(port, accept_handler):
 def accept_conn(listen_sock):
     global client_s
     cl, remote_addr = listen_sock.accept()
+    if uos.dupterm():
+        print("\nConcurrent WebREPL connection from", remote_addr, "rejected")
+        cl.close()
+        return
     print("\nWebREPL connection from:", remote_addr)
     client_s = cl
     websocket_helper.server_handshake(cl)
diff --git a/esp8266/modutime.c b/esp8266/modutime.c
index 4b94ace74..abfe069cc 100644
--- a/esp8266/modutime.c
+++ b/esp8266/modutime.c
@@ -38,6 +38,7 @@
 #include "modpybrtc.h"
 #include "timeutils.h"
 #include "user_interface.h"
+#include "extmod/utime_mphal.h"
 
 /// \module time - time related functions
 ///
@@ -99,53 +100,6 @@ STATIC mp_obj_t time_mktime(mp_obj_t tuple) {
 }
 MP_DEFINE_CONST_FUN_OBJ_1(time_mktime_obj, time_mktime);
 
-/// \function sleep(seconds)
-/// Sleep for the given number of seconds.
-STATIC mp_obj_t time_sleep(mp_obj_t seconds_o) {
-    #if MICROPY_PY_BUILTINS_FLOAT
-    mp_hal_delay_ms(1000 * mp_obj_get_float(seconds_o));
-    #else
-    mp_hal_delay_ms(1000 * mp_obj_get_int(seconds_o));
-    #endif
-    return mp_const_none;
-}
-MP_DEFINE_CONST_FUN_OBJ_1(time_sleep_obj, time_sleep);
-
-STATIC mp_obj_t time_sleep_ms(mp_obj_t arg) {
-    mp_hal_delay_ms(mp_obj_get_int(arg));
-    return mp_const_none;
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(time_sleep_ms_obj, time_sleep_ms);
-
-STATIC mp_obj_t time_sleep_us(mp_obj_t arg) {
-    mp_hal_delay_us(mp_obj_get_int(arg));
-    return mp_const_none;
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(time_sleep_us_obj, time_sleep_us);
-
-STATIC mp_obj_t time_ticks_ms(void) {
-    return MP_OBJ_NEW_SMALL_INT(mp_hal_ticks_ms() & MP_SMALL_INT_POSITIVE_MASK);
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_ms_obj, time_ticks_ms);
-
-STATIC mp_obj_t time_ticks_us(void) {
-    return MP_OBJ_NEW_SMALL_INT(mp_hal_ticks_us() & MP_SMALL_INT_POSITIVE_MASK);
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_us_obj, time_ticks_us);
-
-STATIC mp_obj_t time_ticks_cpu(void) {
-    return MP_OBJ_NEW_SMALL_INT(mp_hal_ticks_cpu() & MP_SMALL_INT_POSITIVE_MASK);
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_cpu_obj, time_ticks_cpu);
-
-STATIC mp_obj_t time_ticks_diff(mp_obj_t start_in, mp_obj_t end_in) {
-    // we assume that the arguments come from ticks_xx so are small ints
-    uint32_t start = MP_OBJ_SMALL_INT_VALUE(start_in);
-    uint32_t end = MP_OBJ_SMALL_INT_VALUE(end_in);
-    return MP_OBJ_NEW_SMALL_INT((end - start) & MP_SMALL_INT_POSITIVE_MASK);
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_2(time_ticks_diff_obj, time_ticks_diff);
-
 /// \function time()
 /// Returns the number of seconds, as an integer, since 1/1/2000.
 STATIC mp_obj_t time_time(void) {
@@ -159,13 +113,13 @@ STATIC const mp_map_elem_t time_module_globals_table[] = {
 
     { MP_OBJ_NEW_QSTR(MP_QSTR_localtime), (mp_obj_t)&time_localtime_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_mktime), (mp_obj_t)&time_mktime_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_sleep), (mp_obj_t)&time_sleep_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_sleep_ms), (mp_obj_t)&time_sleep_ms_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_sleep_us), (mp_obj_t)&time_sleep_us_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_ms), (mp_obj_t)&time_ticks_ms_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_us), (mp_obj_t)&time_ticks_us_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_cpu), (mp_obj_t)&time_ticks_cpu_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_diff), (mp_obj_t)&time_ticks_diff_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_sleep), (mp_obj_t)&mp_utime_sleep_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_sleep_ms), (mp_obj_t)&mp_utime_sleep_ms_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_sleep_us), (mp_obj_t)&mp_utime_sleep_us_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_ms), (mp_obj_t)&mp_utime_ticks_ms_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_us), (mp_obj_t)&mp_utime_ticks_us_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_cpu), (mp_obj_t)&mp_utime_ticks_cpu_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_diff), (mp_obj_t)&mp_utime_ticks_diff_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_time), (mp_obj_t)&time_time_obj },
 };
 
diff --git a/esp8266/mpconfigport.h b/esp8266/mpconfigport.h
index 19cf9a679..602b3e9c8 100644
--- a/esp8266/mpconfigport.h
+++ b/esp8266/mpconfigport.h
@@ -9,6 +9,7 @@
 #define MICROPY_ALLOC_PARSE_RULE_INC    (8)
 #define MICROPY_ALLOC_PARSE_RESULT_INC  (8)
 #define MICROPY_ALLOC_PARSE_CHUNK_INIT  (64)
+#define MICROPY_PERSISTENT_CODE_LOAD (1)
 #define MICROPY_EMIT_X64            (0)
 #define MICROPY_EMIT_THUMB          (0)
 #define MICROPY_EMIT_INLINE_THUMB   (0)
@@ -17,6 +18,7 @@
 #define MICROPY_DEBUG_PRINTER_DEST  mp_debug_print
 #define MICROPY_ENABLE_GC           (1)
 #define MICROPY_STACK_CHECK         (1)
+#define MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF (1)
 #define MICROPY_REPL_EVENT_DRIVEN   (0)
 #define MICROPY_REPL_AUTO_INDENT    (1)
 #define MICROPY_HELPER_REPL         (1)
@@ -33,6 +35,7 @@
 #define MICROPY_PY_BUILTINS_FROZENSET (1)
 #define MICROPY_PY_BUILTINS_SET     (1)
 #define MICROPY_PY_BUILTINS_SLICE   (1)
+#define MICROPY_PY_BUILTINS_SLICE_ATTRS (1)
 #define MICROPY_PY_BUILTINS_PROPERTY (1)
 #define MICROPY_PY___FILE__         (0)
 #define MICROPY_PY_GC               (1)
@@ -49,6 +52,7 @@
 #define MICROPY_PY_SYS_MAXSIZE      (1)
 #define MICROPY_PY_SYS_EXIT         (1)
 #define MICROPY_PY_SYS_STDFILES     (1)
+#define MICROPY_PY_SYS_STDIO_BUFFER (1)
 #define MICROPY_PY_UERRNO           (1)
 #define MICROPY_PY_UBINASCII        (1)
 #define MICROPY_PY_UCTYPES          (1)
@@ -58,6 +62,7 @@
 #define MICROPY_PY_UJSON            (1)
 #define MICROPY_PY_URANDOM          (1)
 #define MICROPY_PY_URE              (1)
+#define MICROPY_PY_UTIME_MP_HAL     (1)
 #define MICROPY_PY_UZLIB            (1)
 #define MICROPY_PY_LWIP             (1)
 #define MICROPY_PY_MACHINE          (1)
@@ -177,4 +182,6 @@ extern const struct _mp_obj_module_t onewire_module;
 #define MICROPY_HW_MCU_NAME "ESP8266"
 #define MICROPY_PY_SYS_PLATFORM "esp8266"
 
+#define MP_FASTCODE(n) __attribute__((section(".iram0.text." #n))) n
+
 #define _assert(expr) ((expr) ? (void)0 : __assert_func(__FILE__, __LINE__, __func__, #expr))
diff --git a/extmod/machine_i2c.c b/extmod/machine_i2c.c
index d76e5eedd..e201b2399 100644
--- a/extmod/machine_i2c.c
+++ b/extmod/machine_i2c.c
@@ -272,7 +272,7 @@ STATIC mp_obj_t machine_i2c_scan(mp_obj_t self_in) {
     // 7-bit addresses 0b0000xxx and 0b1111xxx are reserved
     for (int addr = 0x08; addr < 0x78; ++addr) {
         mp_hal_i2c_start(self);
-        int ack = mp_hal_i2c_write_byte(self, (addr << 1) | 1);
+        int ack = mp_hal_i2c_write_byte(self, (addr << 1));
         if (ack) {
             mp_obj_list_append(list, MP_OBJ_NEW_SMALL_INT(addr));
         }
diff --git a/extmod/modujson.c b/extmod/modujson.c
index 0d0781e06..ca4e6df10 100644
--- a/extmod/modujson.c
+++ b/extmod/modujson.c
@@ -1,9 +1,9 @@
 /*
- * This file is part of the Micro Python project, http://micropython.org/
+ * This file is part of the MicroPython project, http://micropython.org/
  *
  * The MIT License (MIT)
  *
- * Copyright (c) 2014 Damien P. George
+ * Copyright (c) 2014-2016 Damien P. George
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -28,8 +28,10 @@
 
 #include "py/nlr.h"
 #include "py/objlist.h"
+#include "py/objstringio.h"
 #include "py/parsenum.h"
 #include "py/runtime.h"
+#include "py/stream.h"
 
 #if MICROPY_PY_UJSON
 
@@ -42,7 +44,7 @@ STATIC mp_obj_t mod_ujson_dumps(mp_obj_t obj) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_ujson_dumps_obj, mod_ujson_dumps);
 
-// This function implements a simple non-recursive JSON parser.
+// The function below implements a simple non-recursive JSON parser.
 //
 // The JSON specification is at http://www.ietf.org/rfc/rfc4627.txt
 // The parser here will parse any valid JSON and return the correct
@@ -52,13 +54,35 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_ujson_dumps_obj, mod_ujson_dumps);
 // input is outside it's specs.
 //
 // Most of the work is parsing the primitives (null, false, true, numbers,
-// strings).  It does 1 pass over the input string and so is easily extended to
-// being able to parse from a non-seekable stream.  It tries to be fast and
+// strings).  It does 1 pass over the input stream.  It tries to be fast and
 // small in code size, while not using more RAM than necessary.
-STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
-    mp_uint_t len;
-    const char *s = mp_obj_str_get_data(obj, &len);
-    const char *top = s + len;
+
+typedef struct _ujson_stream_t {
+    mp_obj_t stream_obj;
+    mp_uint_t (*read)(mp_obj_t obj, void *buf, mp_uint_t size, int *errcode);
+    int errcode;
+    byte cur;
+} ujson_stream_t;
+
+#define S_EOF (0) // null is not allowed in json stream so is ok as EOF marker
+#define S_END(s) ((s).cur == S_EOF)
+#define S_CUR(s) ((s).cur)
+#define S_NEXT(s) (ujson_stream_next(&(s)))
+
+STATIC byte ujson_stream_next(ujson_stream_t *s) {
+    mp_uint_t ret = s->read(s->stream_obj, &s->cur, 1, &s->errcode);
+    if (s->errcode != 0) {
+        mp_raise_OSError(s->errcode);
+    }
+    if (ret == 0) {
+        s->cur = S_EOF;
+    }
+    return s->cur;
+}
+
+STATIC mp_obj_t mod_ujson_load(mp_obj_t stream_obj) {
+    const mp_stream_p_t *stream_p = mp_get_stream_raise(stream_obj, MP_STREAM_OP_READ);
+    ujson_stream_t s = {stream_obj, stream_p->read, 0, 0};
     vstr_t vstr;
     vstr_init(&vstr, 8);
     mp_obj_list_t stack; // we use a list as a simple stack for nested JSON
@@ -67,41 +91,43 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
     mp_obj_t stack_top = MP_OBJ_NULL;
     mp_obj_type_t *stack_top_type = NULL;
     mp_obj_t stack_key = MP_OBJ_NULL;
+    S_NEXT(s);
     for (;;) {
         cont:
-        if (s == top) {
+        if (S_END(s)) {
             break;
         }
         mp_obj_t next = MP_OBJ_NULL;
         bool enter = false;
-        switch (*s) {
+        byte cur = S_CUR(s);
+        S_NEXT(s);
+        switch (cur) {
             case ',':
             case ':':
             case ' ':
             case '\t':
             case '\n':
             case '\r':
-                s += 1;
                 goto cont;
             case 'n':
-                if (s + 3 < top && s[1] == 'u' && s[2] == 'l' && s[3] == 'l') {
-                    s += 4;
+                if (S_CUR(s) == 'u' && S_NEXT(s) == 'l' && S_NEXT(s) == 'l') {
+                    S_NEXT(s);
                     next = mp_const_none;
                 } else {
                     goto fail;
                 }
                 break;
             case 'f':
-                if (s + 4 < top && s[1] == 'a' && s[2] == 'l' && s[3] == 's' && s[4] == 'e') {
-                    s += 5;
+                if (S_CUR(s) == 'a' && S_NEXT(s) == 'l' && S_NEXT(s) == 's' && S_NEXT(s) == 'e') {
+                    S_NEXT(s);
                     next = mp_const_false;
                 } else {
                     goto fail;
                 }
                 break;
             case 't':
-                if (s + 3 < top && s[1] == 'r' && s[2] == 'u' && s[3] == 'e') {
-                    s += 4;
+                if (S_CUR(s) == 'r' && S_NEXT(s) == 'u' && S_NEXT(s) == 'e') {
+                    S_NEXT(s);
                     next = mp_const_true;
                 } else {
                     goto fail;
@@ -109,11 +135,10 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
                 break;
             case '"':
                 vstr_reset(&vstr);
-                for (s++; s < top && *s != '"';) {
-                    byte c = *s;
+                for (; !S_END(s) && S_CUR(s) != '"';) {
+                    byte c = S_CUR(s);
                     if (c == '\\') {
-                        s++;
-                        c = *s;
+                        c = S_NEXT(s);
                         switch (c) {
                             case 'b': c = 0x08; break;
                             case 'f': c = 0x0c; break;
@@ -121,10 +146,9 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
                             case 'r': c = 0x0d; break;
                             case 't': c = 0x09; break;
                             case 'u': {
-                                if (s + 4 >= top) { goto fail; }
                                 mp_uint_t num = 0;
                                 for (int i = 0; i < 4; i++) {
-                                    c = (*++s | 0x20) - '0';
+                                    c = (S_NEXT(s) | 0x20) - '0';
                                     if (c > 9) {
                                         c -= ('a' - ('9' + 1));
                                     }
@@ -137,27 +161,29 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
                     }
                     vstr_add_byte(&vstr, c);
                 str_cont:
-                    s++;
+                    S_NEXT(s);
                 }
-                if (s == top) {
+                if (S_END(s)) {
                     goto fail;
                 }
-                s++;
+                S_NEXT(s);
                 next = mp_obj_new_str(vstr.buf, vstr.len, false);
                 break;
             case '-':
             case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': {
                 bool flt = false;
                 vstr_reset(&vstr);
-                for (; s < top; s++) {
-                    if (*s == '.' || *s == 'E' || *s == 'e') {
+                for (;;) {
+                    vstr_add_byte(&vstr, cur);
+                    cur = S_CUR(s);
+                    if (cur == '.' || cur == 'E' || cur == 'e') {
                         flt = true;
-                    } else if (*s == '-' || unichar_isdigit(*s)) {
+                    } else if (cur == '-' || unichar_isdigit(cur)) {
                         // pass
                     } else {
                         break;
                     }
-                    vstr_add_byte(&vstr, *s);
+                    S_NEXT(s);
                 }
                 if (flt) {
                     next = mp_parse_num_decimal(vstr.buf, vstr.len, false, false, NULL);
@@ -169,16 +195,13 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
             case '[':
                 next = mp_obj_new_list(0, NULL);
                 enter = true;
-                s += 1;
                 break;
             case '{':
                 next = mp_obj_new_dict(0);
                 enter = true;
-                s += 1;
                 break;
             case '}':
             case ']': {
-                s += 1;
                 if (stack_top == MP_OBJ_NULL) {
                     // no object at all
                     goto fail;
@@ -231,10 +254,10 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
     }
     success:
     // eat trailing whitespace
-    while (s < top && unichar_isspace(*s)) {
-        s++;
+    while (unichar_isspace(S_CUR(s))) {
+        S_NEXT(s);
     }
-    if (s < top) {
+    if (!S_END(s)) {
         // unexpected chars
         goto fail;
     }
@@ -248,11 +271,21 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
     fail:
     nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "syntax error in JSON"));
 }
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_ujson_load_obj, mod_ujson_load);
+
+STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
+    mp_uint_t len;
+    const char *buf = mp_obj_str_get_data(obj, &len);
+    vstr_t vstr = {len, len, (char*)buf, true};
+    mp_obj_stringio_t sio = {{&mp_type_stringio}, &vstr, 0};
+    return mod_ujson_load(MP_OBJ_FROM_PTR(&sio));
+}
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_ujson_loads_obj, mod_ujson_loads);
 
 STATIC const mp_rom_map_elem_t mp_module_ujson_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_ujson) },
     { MP_ROM_QSTR(MP_QSTR_dumps), MP_ROM_PTR(&mod_ujson_dumps_obj) },
+    { MP_ROM_QSTR(MP_QSTR_load), MP_ROM_PTR(&mod_ujson_load_obj) },
     { MP_ROM_QSTR(MP_QSTR_loads), MP_ROM_PTR(&mod_ujson_loads_obj) },
 };
 
diff --git a/extmod/modussl_mbedtls.c b/extmod/modussl_mbedtls.c
index ddb7ba0fe..5a7a745d8 100644
--- a/extmod/modussl_mbedtls.c
+++ b/extmod/modussl_mbedtls.c
@@ -215,6 +215,16 @@ STATIC mp_uint_t socket_write(mp_obj_t o_in, const void *buf, mp_uint_t size, in
     return MP_STREAM_ERROR;
 }
 
+STATIC mp_obj_t socket_setblocking(mp_obj_t self_in, mp_obj_t flag_in) {
+    // Currently supports only blocking mode
+    (void)self_in;
+    if (!mp_obj_is_true(flag_in)) {
+        mp_not_implemented("");
+    }
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(socket_setblocking_obj, socket_setblocking);
+
 STATIC mp_obj_t socket_close(mp_obj_t self_in) {
     mp_obj_ssl_socket_t *self = MP_OBJ_TO_PTR(self_in);
 
@@ -236,6 +246,7 @@ STATIC const mp_rom_map_elem_t ussl_socket_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_readinto), MP_ROM_PTR(&mp_stream_readinto_obj) },
     { MP_ROM_QSTR(MP_QSTR_readline), MP_ROM_PTR(&mp_stream_unbuffered_readline_obj) },
     { MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&mp_stream_write_obj) },
+    { MP_ROM_QSTR(MP_QSTR_setblocking), MP_ROM_PTR(&socket_setblocking_obj) },
     { MP_ROM_QSTR(MP_QSTR_close), MP_ROM_PTR(&socket_close_obj) },
 };
 
diff --git a/extmod/utime_mphal.c b/extmod/utime_mphal.c
new file mode 100644
index 000000000..3ecdc9446
--- /dev/null
+++ b/extmod/utime_mphal.c
@@ -0,0 +1,89 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013-2016 Damien P. George
+ * Copyright (c) 2016 Paul Sokolovsky
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/mpconfig.h"
+#if MICROPY_PY_UTIME_MP_HAL
+
+#include <string.h>
+
+#include "py/obj.h"
+#include "py/mphal.h"
+#include "py/smallint.h"
+#include "extmod/utime_mphal.h"
+
+STATIC mp_obj_t time_sleep(mp_obj_t seconds_o) {
+    #if MICROPY_PY_BUILTINS_FLOAT
+    mp_hal_delay_ms(1000 * mp_obj_get_float(seconds_o));
+    #else
+    mp_hal_delay_ms(1000 * mp_obj_get_int(seconds_o));
+    #endif
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_1(mp_utime_sleep_obj, time_sleep);
+
+STATIC mp_obj_t time_sleep_ms(mp_obj_t arg) {
+    mp_int_t ms = mp_obj_get_int(arg);
+    if (ms > 0) {
+        mp_hal_delay_ms(ms);
+    }
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_1(mp_utime_sleep_ms_obj, time_sleep_ms);
+
+STATIC mp_obj_t time_sleep_us(mp_obj_t arg) {
+    mp_int_t us = mp_obj_get_int(arg);
+    if (us > 0) {
+        mp_hal_delay_us(us);
+    }
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_1(mp_utime_sleep_us_obj, time_sleep_us);
+
+STATIC mp_obj_t time_ticks_ms(void) {
+    return MP_OBJ_NEW_SMALL_INT(mp_hal_ticks_ms() & MP_SMALL_INT_POSITIVE_MASK);
+}
+MP_DEFINE_CONST_FUN_OBJ_0(mp_utime_ticks_ms_obj, time_ticks_ms);
+
+STATIC mp_obj_t time_ticks_us(void) {
+    return MP_OBJ_NEW_SMALL_INT(mp_hal_ticks_us() & MP_SMALL_INT_POSITIVE_MASK);
+}
+MP_DEFINE_CONST_FUN_OBJ_0(mp_utime_ticks_us_obj, time_ticks_us);
+
+STATIC mp_obj_t time_ticks_cpu(void) {
+    return MP_OBJ_NEW_SMALL_INT(mp_hal_ticks_cpu() & MP_SMALL_INT_POSITIVE_MASK);
+}
+MP_DEFINE_CONST_FUN_OBJ_0(mp_utime_ticks_cpu_obj, time_ticks_cpu);
+
+STATIC mp_obj_t time_ticks_diff(mp_obj_t start_in, mp_obj_t end_in) {
+    // we assume that the arguments come from ticks_xx so are small ints
+    uint32_t start = MP_OBJ_SMALL_INT_VALUE(start_in);
+    uint32_t end = MP_OBJ_SMALL_INT_VALUE(end_in);
+    return MP_OBJ_NEW_SMALL_INT((end - start) & MP_SMALL_INT_POSITIVE_MASK);
+}
+MP_DEFINE_CONST_FUN_OBJ_2(mp_utime_ticks_diff_obj, time_ticks_diff);
+
+#endif // MICROPY_PY_UTIME_MP_HAL
diff --git a/extmod/utime_mphal.h b/extmod/utime_mphal.h
new file mode 100644
index 000000000..4f2395a09
--- /dev/null
+++ b/extmod/utime_mphal.h
@@ -0,0 +1,36 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013-2016 Damien P. George
+ * Copyright (c) 2016 Paul Sokolovsky
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/obj.h"
+
+MP_DECLARE_CONST_FUN_OBJ(mp_utime_sleep_obj);
+MP_DECLARE_CONST_FUN_OBJ(mp_utime_sleep_ms_obj);
+MP_DECLARE_CONST_FUN_OBJ(mp_utime_sleep_us_obj);
+MP_DECLARE_CONST_FUN_OBJ(mp_utime_ticks_ms_obj);
+MP_DECLARE_CONST_FUN_OBJ(mp_utime_ticks_us_obj);
+MP_DECLARE_CONST_FUN_OBJ(mp_utime_ticks_cpu_obj);
+MP_DECLARE_CONST_FUN_OBJ(mp_utime_ticks_diff_obj);
diff --git a/extmod/uzlib/tinf.h b/extmod/uzlib/tinf.h
index 3545bbd88..106203a09 100644
--- a/extmod/uzlib/tinf.h
+++ b/extmod/uzlib/tinf.h
@@ -32,6 +32,7 @@ extern "C" {
 #define TINF_DONE           1
 #define TINF_DATA_ERROR    (-3)
 #define TINF_CHKSUM_ERROR  (-4)
+#define TINF_DICT_ERROR    (-5)
 
 /* checksum types */
 #define TINF_CHKSUM_NONE  0
diff --git a/extmod/uzlib/tinflate.c b/extmod/uzlib/tinflate.c
index 0e53f7f07..58850eb4a 100644
--- a/extmod/uzlib/tinflate.c
+++ b/extmod/uzlib/tinflate.c
@@ -361,6 +361,9 @@ static int tinf_inflate_block_data(TINF_DATA *d, TINF_TREE *lt, TINF_TREE *dt)
         /* possibly get more bits from distance code */
         offs = tinf_read_bits(d, dist_bits[dist], dist_base[dist]);
         if (d->dict_ring) {
+            if (offs > d->dict_size) {
+                return TINF_DICT_ERROR;
+            }
             d->lzOff = d->dict_idx - offs;
             if (d->lzOff < 0) {
                 d->lzOff += d->dict_size;
diff --git a/extmod/vfs_fat.c b/extmod/vfs_fat.c
index 3a17533e4..6e827fc66 100644
--- a/extmod/vfs_fat.c
+++ b/extmod/vfs_fat.c
@@ -31,6 +31,7 @@
 #include <string.h>
 #include "py/nlr.h"
 #include "py/runtime.h"
+#include "py/mperrno.h"
 #include "lib/fatfs/ff.h"
 #include "lib/fatfs/diskio.h"
 #include "extmod/vfs_fat_file.h"
@@ -76,24 +77,42 @@ STATIC mp_obj_t fat_vfs_listdir_func(size_t n_args, const mp_obj_t *args) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(fat_vfs_listdir_obj, 1, 2, fat_vfs_listdir_func);
 
-STATIC mp_obj_t fat_vfs_remove(mp_obj_t vfs_in, mp_obj_t path_in) {
-    (void)vfs_in;
+STATIC mp_obj_t fat_vfs_remove_internal(mp_obj_t path_in, mp_int_t attr) {
     const char *path = mp_obj_str_get_str(path_in);
-    // TODO check that path is actually a file before trying to unlink it
-    FRESULT res = f_unlink(path);
-    if (res == FR_OK) {
+
+    FILINFO fno;
+#if _USE_LFN
+    fno.lfname = NULL;
+    fno.lfsize = 0;
+#endif
+    FRESULT res = f_stat(path, &fno);
+
+    if (res != FR_OK) {
+        mp_raise_OSError(fresult_to_errno_table[res]);
+    }
+
+    // check if path is a file or directory
+    if ((fno.fattrib & AM_DIR) == attr) {
+        res = f_unlink(path);
+
+        if (res != FR_OK) {
+            mp_raise_OSError(fresult_to_errno_table[res]);
+        }
         return mp_const_none;
     } else {
-        mp_raise_OSError(fresult_to_errno_table[res]);
+        mp_raise_OSError(attr ? MP_ENOTDIR : MP_EISDIR);
     }
 }
+
+STATIC mp_obj_t fat_vfs_remove(mp_obj_t vfs_in, mp_obj_t path_in) {
+    (void)vfs_in;
+    return fat_vfs_remove_internal(path_in, 0); // 0 == file attribute
+}
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(fat_vfs_remove_obj, fat_vfs_remove);
 
 STATIC mp_obj_t fat_vfs_rmdir(mp_obj_t vfs_in, mp_obj_t path_in) {
-    // TODO: Currently just redirects to fat_vfs_remove(), which are
-    // backed by the same underlying FatFs function. Should at least
-    // check that path is actually a dir.
-    return fat_vfs_remove(vfs_in, path_in);
+    (void) vfs_in;
+    return fat_vfs_remove_internal(path_in, AM_DIR);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(fat_vfs_rmdir_obj, fat_vfs_rmdir);
 
diff --git a/extmod/vfs_fat_file.c b/extmod/vfs_fat_file.c
index ecc9ed70f..e269ef593 100644
--- a/extmod/vfs_fat_file.c
+++ b/extmod/vfs_fat_file.c
@@ -110,14 +110,20 @@ STATIC mp_uint_t file_obj_write(mp_obj_t self_in, const void *buf, mp_uint_t siz
 
 STATIC mp_obj_t file_obj_flush(mp_obj_t self_in) {
     pyb_file_obj_t *self = MP_OBJ_TO_PTR(self_in);
-    f_sync(&self->fp);
+    FRESULT res = f_sync(&self->fp);
+    if (res != FR_OK) {
+        mp_raise_OSError(fresult_to_errno_table[res]);
+    }
     return mp_const_none;
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(file_obj_flush_obj, file_obj_flush);
 
 STATIC mp_obj_t file_obj_close(mp_obj_t self_in) {
     pyb_file_obj_t *self = MP_OBJ_TO_PTR(self_in);
-    f_close(&self->fp);
+    FRESULT res = f_close(&self->fp);
+    if (res != FR_OK) {
+        mp_raise_OSError(fresult_to_errno_table[res]);
+    }
     return mp_const_none;
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(file_obj_close_obj, file_obj_close);
diff --git a/lib/utils/pyexec.c b/lib/utils/pyexec.c
index bc540199d..f9bbf68a1 100644
--- a/lib/utils/pyexec.c
+++ b/lib/utils/pyexec.c
@@ -45,6 +45,7 @@
 #include "genhdr/mpversion.h"
 
 pyexec_mode_kind_t pyexec_mode_kind = PYEXEC_MODE_FRIENDLY_REPL;
+int pyexec_system_exit = 0;
 STATIC bool repl_display_debugging_info = 0;
 
 #define EXEC_FLAG_PRINT_EOF (1)
@@ -61,6 +62,9 @@ STATIC int parse_compile_execute(void *source, mp_parse_input_kind_t input_kind,
     int ret = 0;
     uint32_t start = 0;
 
+    // by default a SystemExit exception returns 0
+    pyexec_system_exit = 0;
+
     nlr_buf_t nlr;
     if (nlr_push(&nlr) == 0) {
         mp_obj_t module_fun;
@@ -99,7 +103,7 @@ STATIC int parse_compile_execute(void *source, mp_parse_input_kind_t input_kind,
         // check for SystemExit
         if (mp_obj_is_subclass_fast(mp_obj_get_type((mp_obj_t)nlr.ret_val), &mp_type_SystemExit)) {
             // at the moment, the value of SystemExit is unused
-            ret = PYEXEC_FORCED_EXIT;
+            ret = pyexec_system_exit;
         } else {
             mp_obj_print_exception(&mp_plat_print, (mp_obj_t)nlr.ret_val);
             ret = 0;
@@ -148,7 +152,7 @@ STATIC int pyexec_raw_repl_process_char(int c);
 STATIC int pyexec_friendly_repl_process_char(int c);
 
 void pyexec_event_repl_init(void) {
-    MP_STATE_VM(repl_line) = vstr_new_size(32);
+    MP_STATE_VM(repl_line) = vstr_new(32);
     repl.cont_line = false;
     readline_init(MP_STATE_VM(repl_line), ">>> ");
     if (pyexec_mode_kind == PYEXEC_MODE_RAW_REPL) {
diff --git a/lib/utils/pyexec.h b/lib/utils/pyexec.h
index e0f62440e..ae69a195e 100644
--- a/lib/utils/pyexec.h
+++ b/lib/utils/pyexec.h
@@ -33,6 +33,11 @@ typedef enum {
 
 extern pyexec_mode_kind_t pyexec_mode_kind;
 
+// Set this to the value (eg PYEXEC_FORCED_EXIT) that will be propagated through
+// the pyexec functions if a SystemExit exception is raised by the running code.
+// It will reset to 0 at the start of each execution (eg each REPL entry).
+extern int pyexec_system_exit;
+
 #define PYEXEC_FORCED_EXIT (0x100)
 #define PYEXEC_SWITCH_MODE (0x200)
 
diff --git a/py/argcheck.c b/py/argcheck.c
index a6c769ee8..8cef10b16 100644
--- a/py/argcheck.c
+++ b/py/argcheck.c
@@ -37,8 +37,7 @@ void mp_arg_check_num(size_t n_args, size_t n_kw, size_t n_args_min, size_t n_ar
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
             mp_arg_error_terse_mismatch();
         } else {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "function does not take keyword arguments"));
+            mp_raise_msg(&mp_type_TypeError, "function does not take keyword arguments");
         }
     }
 
@@ -116,8 +115,7 @@ void mp_arg_parse_all(size_t n_pos, const mp_obj_t *pos, mp_map_t *kws, size_t n
             mp_arg_error_terse_mismatch();
         } else {
             // TODO better error message
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "extra positional arguments given"));
+            mp_raise_msg(&mp_type_TypeError, "extra positional arguments given");
         }
     }
     if (kws_found < kws->used) {
@@ -125,8 +123,7 @@ void mp_arg_parse_all(size_t n_pos, const mp_obj_t *pos, mp_map_t *kws, size_t n
             mp_arg_error_terse_mismatch();
         } else {
             // TODO better error message
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "extra keyword arguments given"));
+            mp_raise_msg(&mp_type_TypeError, "extra keyword arguments given");
         }
     }
 }
@@ -139,7 +136,7 @@ void mp_arg_parse_all_kw_array(size_t n_pos, size_t n_kw, const mp_obj_t *args,
 
 #if MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE || _MSC_VER
 NORETURN void mp_arg_error_terse_mismatch(void) {
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "argument num/types mismatch"));
+    mp_raise_msg(&mp_type_TypeError, "argument num/types mismatch");
 }
 #endif
 
diff --git a/py/bc.c b/py/bc.c
index e5abea244..07de08fc3 100644
--- a/py/bc.c
+++ b/py/bc.c
@@ -185,7 +185,7 @@ void mp_setup_code_state(mp_code_state_t *code_state, mp_obj_fun_bc_t *self, siz
             }
             // Didn't find name match with positional args
             if ((scope_flags & MP_SCOPE_FLAG_VARKEYWORDS) == 0) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "function does not take keyword arguments"));
+                mp_raise_msg(&mp_type_TypeError, "function does not take keyword arguments");
             }
             mp_obj_dict_store(dict, kwargs[2 * i], kwargs[2 * i + 1]);
 continue2:;
@@ -234,8 +234,7 @@ continue2:;
     } else {
         // no keyword arguments given
         if (n_kwonly_args != 0) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "function missing keyword-only argument"));
+            mp_raise_msg(&mp_type_TypeError, "function missing keyword-only argument");
         }
         if ((scope_flags & MP_SCOPE_FLAG_VARKEYWORDS) != 0) {
             *var_pos_kw_args = mp_obj_new_dict(0);
diff --git a/py/builtinevex.c b/py/builtinevex.c
index 74c43b176..636f86930 100644
--- a/py/builtinevex.c
+++ b/py/builtinevex.c
@@ -95,7 +95,7 @@ STATIC mp_obj_t mp_builtin_compile(size_t n_args, const mp_obj_t *args) {
         case MP_QSTR_exec: parse_input_kind = MP_PARSE_FILE_INPUT; break;
         case MP_QSTR_eval: parse_input_kind = MP_PARSE_EVAL_INPUT; break;
         default:
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "bad compile mode"));
+            mp_raise_msg(&mp_type_ValueError, "bad compile mode");
     }
 
     mp_obj_code_t *code = m_new_obj(mp_obj_code_t);
diff --git a/py/builtinimport.c b/py/builtinimport.c
index e4199f25d..e72eaf472 100644
--- a/py/builtinimport.c
+++ b/py/builtinimport.c
@@ -138,7 +138,7 @@ STATIC void do_load_from_lexer(mp_obj_t module_obj, mp_lexer_t *lex, const char
     if (lex == NULL) {
         // we verified the file exists using stat, but lexer could still fail
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ImportError, "module not found"));
+            mp_raise_msg(&mp_type_ImportError, "module not found");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ImportError,
                 "no module named '%s'", fname));
@@ -340,7 +340,7 @@ mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
             DEBUG_printf("Warning: no dots in current module name and level>0\n");
             p = this_name + this_name_l;
         } else if (level != -1) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ImportError, "Invalid relative import"));
+            mp_raise_msg(&mp_type_ImportError, "invalid relative import");
         }
 
         uint new_mod_l = (mod_len == 0 ? (size_t)(p - this_name) : (size_t)(p - this_name) + 1 + mod_len);
@@ -355,7 +355,7 @@ mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
         DEBUG_printf("Resolved base name for relative import: '%s'\n", qstr_str(new_mod_q));
         if (new_mod_q == MP_QSTR_) {
             // CPython raises SystemError
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ImportError, "cannot perform relative import"));
+            mp_raise_msg(&mp_type_ImportError, "cannot perform relative import");
         }
         module_name = MP_OBJ_NEW_QSTR(new_mod_q);
         mod_str = new_mod;
@@ -425,7 +425,7 @@ mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
                 #endif
                     // couldn't find the file, so fail
                     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-                        nlr_raise(mp_obj_new_exception_msg(&mp_type_ImportError, "module not found"));
+                        mp_raise_msg(&mp_type_ImportError, "module not found");
                     } else {
                         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ImportError,
                             "no module named '%q'", mod_name));
diff --git a/py/compile.c b/py/compile.c
index 0ea8a3c15..f84d5e214 100644
--- a/py/compile.c
+++ b/py/compile.c
@@ -2723,15 +2723,8 @@ STATIC void compile_node(compiler_t *comp, mp_parse_node_t pn) {
         mp_parse_node_struct_t *pns = (mp_parse_node_struct_t*)pn;
         EMIT_ARG(set_source_line, pns->source_line);
         compile_function_t f = compile_function[MP_PARSE_NODE_STRUCT_KIND(pns)];
-        if (f == NULL) {
-#if MICROPY_DEBUG_PRINTERS
-            printf("node %u cannot be compiled\n", (uint)MP_PARSE_NODE_STRUCT_KIND(pns));
-            mp_parse_node_print(pn, 0);
-#endif
-            compile_syntax_error(comp, pn, "internal compiler error");
-        } else {
-            f(comp, pns);
-        }
+        assert(f != NULL);
+        f(comp, pns);
     }
 }
 
@@ -2836,12 +2829,10 @@ STATIC void compile_scope_func_annotations(compiler_t *comp, mp_parse_node_t pn)
             // no annotation
             return;
         }
-    } else if (MP_PARSE_NODE_STRUCT_KIND(pns) == PN_typedargslist_dbl_star) {
+    } else {
+        assert(MP_PARSE_NODE_STRUCT_KIND(pns) == PN_typedargslist_dbl_star);
         // double star with possible annotation
         // fallthrough
-    } else {
-        // no annotation
-        return;
     }
 
     mp_parse_node_t pn_annotation = pns->nodes[1];
diff --git a/py/emitglue.c b/py/emitglue.c
index 2bfc4ad82..c81387fd4 100644
--- a/py/emitglue.c
+++ b/py/emitglue.c
@@ -425,7 +425,7 @@ mp_raw_code_t *mp_raw_code_load_file(const char *filename) {
     return rc;
 }
 
-#elif defined(__thumb2__) || defined(__thumb__)
+#elif defined(__thumb2__) || defined(__thumb__) || defined(__xtensa__)
 // fatfs file reader (assume thumb2 arch uses fatfs...)
 
 #include "lib/fatfs/ff.h"
diff --git a/py/lexer.c b/py/lexer.c
index b2c9c5ff7..4a7c8f580 100644
--- a/py/lexer.c
+++ b/py/lexer.c
@@ -343,7 +343,6 @@ STATIC void mp_lexer_next_token_into(mp_lexer_t *lex, bool first_token) {
         lex->tok_kind = MP_TOKEN_NEWLINE;
 
         mp_uint_t num_spaces = lex->column - 1;
-        lex->emit_dent = 0;
         if (num_spaces == indent_top(lex)) {
         } else if (num_spaces > indent_top(lex)) {
             indent_push(lex, num_spaces);
@@ -359,16 +358,7 @@ STATIC void mp_lexer_next_token_into(mp_lexer_t *lex, bool first_token) {
         }
 
     } else if (is_end(lex)) {
-        if (indent_top(lex) > 0) {
-            lex->tok_kind = MP_TOKEN_NEWLINE;
-            lex->emit_dent = 0;
-            while (indent_top(lex) > 0) {
-                indent_pop(lex);
-                lex->emit_dent -= 1;
-            }
-        } else {
-            lex->tok_kind = MP_TOKEN_END;
-        }
+        lex->tok_kind = MP_TOKEN_END;
 
     } else if (is_char_or(lex, '\'', '\"')
                || (is_char_or3(lex, 'r', 'u', 'b') && is_char_following_or(lex, '\'', '\"'))
diff --git a/py/misc.h b/py/misc.h
index 3ed227a35..e60665e59 100644
--- a/py/misc.h
+++ b/py/misc.h
@@ -151,8 +151,7 @@ void vstr_init_fixed_buf(vstr_t *vstr, size_t alloc, char *buf);
 struct _mp_print_t;
 void vstr_init_print(vstr_t *vstr, size_t alloc, struct _mp_print_t *print);
 void vstr_clear(vstr_t *vstr);
-vstr_t *vstr_new(void);
-vstr_t *vstr_new_size(size_t alloc);
+vstr_t *vstr_new(size_t alloc);
 void vstr_free(vstr_t *vstr);
 static inline void vstr_reset(vstr_t *vstr) { vstr->len = 0; }
 static inline char *vstr_str(vstr_t *vstr) { return vstr->buf; }
diff --git a/py/modbuiltins.c b/py/modbuiltins.c
index 29f84d6c2..57e52efa5 100644
--- a/py/modbuiltins.c
+++ b/py/modbuiltins.c
@@ -178,7 +178,7 @@ STATIC mp_obj_t mp_builtin_chr(mp_obj_t o_in) {
         str[3] = (c & 0x3F) | 0x80;
         len = 4;
     } else {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "chr() arg not in range(0x110000)"));
+        mp_raise_msg(&mp_type_ValueError, "chr() arg not in range(0x110000)");
     }
     return mp_obj_new_str(str, len, true);
     #else
@@ -187,7 +187,7 @@ STATIC mp_obj_t mp_builtin_chr(mp_obj_t o_in) {
         char str[1] = {ord};
         return mp_obj_new_str(str, 1, true);
     } else {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "chr() arg not in range(256)"));
+        mp_raise_msg(&mp_type_ValueError, "chr() arg not in range(256)");
     }
     #endif
 }
@@ -286,7 +286,7 @@ STATIC mp_obj_t mp_builtin_min_max(size_t n_args, const mp_obj_t *args, mp_map_t
             if (default_elem != NULL) {
                 best_obj = default_elem->value;
             } else {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "arg is an empty sequence"));
+                mp_raise_msg(&mp_type_ValueError, "arg is an empty sequence");
             }
         }
         return best_obj;
@@ -507,8 +507,7 @@ MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_builtin_sum_obj, 1, 2, mp_builtin_sum);
 
 STATIC mp_obj_t mp_builtin_sorted(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs) {
     if (n_args > 1) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                                          "must use keyword argument for key function"));
+        mp_raise_msg(&mp_type_TypeError, "must use keyword argument for key function");
     }
     mp_obj_t self = mp_type_list.make_new(&mp_type_list, 1, 0, args);
     mp_obj_list_sort(1, &self, kwargs);
diff --git a/py/modmicropython.c b/py/modmicropython.c
index f7d74db2e..675d169cc 100644
--- a/py/modmicropython.c
+++ b/py/modmicropython.c
@@ -34,6 +34,16 @@
 // Various builtins specific to MicroPython runtime,
 // living in micropython module
 
+STATIC mp_obj_t mp_micropython_opt_level(size_t n_args, const mp_obj_t *args) {
+    if (n_args == 0) {
+        return MP_OBJ_NEW_SMALL_INT(MP_STATE_VM(mp_optimise_value));
+    } else {
+        MP_STATE_VM(mp_optimise_value) = mp_obj_get_int(args[0]);
+        return mp_const_none;
+    }
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_micropython_opt_level_obj, 0, 1, mp_micropython_opt_level);
+
 #if MICROPY_PY_MICROPYTHON_MEM_INFO
 
 #if MICROPY_MEM_STATS
@@ -121,6 +131,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(mp_alloc_emergency_exception_buf_obj, mp_alloc_
 STATIC const mp_rom_map_elem_t mp_module_micropython_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_micropython) },
     { MP_ROM_QSTR(MP_QSTR_const), MP_ROM_PTR(&mp_identity_obj) },
+    { MP_ROM_QSTR(MP_QSTR_opt_level), MP_ROM_PTR(&mp_micropython_opt_level_obj) },
 #if MICROPY_PY_MICROPYTHON_MEM_INFO
 #if MICROPY_MEM_STATS
     { MP_ROM_QSTR(MP_QSTR_mem_total), MP_ROM_PTR(&mp_micropython_mem_total_obj) },
diff --git a/py/modthread.c b/py/modthread.c
index c358cdf9e..6f55281ad 100644
--- a/py/modthread.c
+++ b/py/modthread.c
@@ -239,7 +239,7 @@ STATIC mp_obj_t mod_thread_start_new_thread(size_t n_args, const mp_obj_t *args)
     } else {
         // positional and keyword arguments
         if (mp_obj_get_type(args[2]) != &mp_type_dict) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "expecting a dict for keyword args"));
+            mp_raise_msg(&mp_type_TypeError, "expecting a dict for keyword args");
         }
         mp_map_t *map = &((mp_obj_dict_t*)MP_OBJ_TO_PTR(args[2]))->map;
         th_args = m_new_obj_var(thread_entry_args_t, mp_obj_t, pos_args_len + 2 * map->used);
diff --git a/py/mpconfig.h b/py/mpconfig.h
index e33a41f7a..dcdaffe0f 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -860,6 +860,12 @@ typedef double mp_float_t;
 #define MICROPY_PY_UERRNO (0)
 #endif
 
+// Whether to provide "utime" module functions implementation
+// in terms of mp_hal_* functions.
+#ifndef MICROPY_PY_UTIME_MP_HAL
+#define MICROPY_PY_UTIME_MP_HAL (0)
+#endif
+
 // Whether to provide "_thread" module
 #ifndef MICROPY_PY_THREAD
 #define MICROPY_PY_THREAD (0)
diff --git a/py/mphal.h b/py/mphal.h
index 54a45b024..8d5654f9e 100644
--- a/py/mphal.h
+++ b/py/mphal.h
@@ -66,6 +66,10 @@ mp_uint_t mp_hal_ticks_ms(void);
 mp_uint_t mp_hal_ticks_us(void);
 #endif
 
+#ifndef mp_hal_ticks_cpu
+mp_uint_t mp_hal_ticks_cpu(void);
+#endif
+
 // If port HAL didn't define its own pin API, use generic
 // "virtual pin" API from the core.
 #ifndef mp_hal_pin_obj_t
diff --git a/py/mpprint.c b/py/mpprint.c
index 97ea33ad2..9ad0f3f9a 100644
--- a/py/mpprint.c
+++ b/py/mpprint.c
@@ -252,8 +252,8 @@ int mp_print_mp_int(const mp_print_t *print, mp_obj_t x, int base, int base_char
     // enough, a dynamic one will be allocated.
     char stack_buf[sizeof(mp_int_t) * 4];
     char *buf = stack_buf;
-    mp_uint_t buf_size = sizeof(stack_buf);
-    mp_uint_t fmt_size = 0;
+    size_t buf_size = sizeof(stack_buf);
+    size_t fmt_size = 0;
     char *str;
 
     if (prec > 1) {
diff --git a/py/mpz.c b/py/mpz.c
index bb7647956..cceb079cd 100644
--- a/py/mpz.c
+++ b/py/mpz.c
@@ -645,18 +645,6 @@ STATIC void mpn_div(mpz_dig_t *num_dig, mp_uint_t *num_len, const mpz_dig_t *den
 
 #define MIN_ALLOC (2)
 
-STATIC const uint8_t log_base2_floor[] = {
-    0,
-    0, 1, 1, 2,
-    2, 2, 2, 3,
-    3, 3, 3, 3,
-    3, 3, 3, 4,
-    4, 4, 4, 4,
-    4, 4, 4, 4,
-    4, 4, 4, 4,
-    4, 4, 4, 5
-};
-
 void mpz_init_zero(mpz_t *z) {
     z->neg = 0;
     z->fixed_dig = 0;
@@ -734,11 +722,9 @@ STATIC void mpz_need_dig(mpz_t *z, mp_uint_t need) {
     }
 
     if (z->dig == NULL || z->alloc < need) {
-        if (z->fixed_dig) {
-            // cannot reallocate fixed buffers
-            assert(0);
-            return;
-        }
+        // if z has fixed digit buffer there's not much we can do as the caller will
+        // be expecting a buffer with at least "need" bytes (but it shouldn't happen)
+        assert(!z->fixed_dig);
         z->dig = m_renew(mpz_dig_t, z->dig, z->alloc, need);
         z->alloc = need;
     }
@@ -1497,13 +1483,10 @@ mpz_t *mpz_lcm(const mpz_t *z1, const mpz_t *z2) {
        quo * rhs + rem = lhs
        0 <= rem < rhs
    can have lhs, rhs the same
+   assumes rhs != 0 (undefined behaviour if it is)
 */
 void mpz_divmod_inpl(mpz_t *dest_quo, mpz_t *dest_rem, const mpz_t *lhs, const mpz_t *rhs) {
-    if (rhs->len == 0) {
-        mpz_set_from_int(dest_quo, 0);
-        mpz_set_from_int(dest_rem, 0);
-        return;
-    }
+    assert(!mpz_is_zero(rhs));
 
     mpz_need_dig(dest_quo, lhs->len + 1); // +1 necessary?
     memset(dest_quo->dig, 0, (lhs->len + 1) * sizeof(mpz_dig_t));
@@ -1657,18 +1640,6 @@ mp_float_t mpz_as_float(const mpz_t *i) {
 }
 #endif
 
-mp_uint_t mpz_as_str_size(const mpz_t *i, mp_uint_t base, const char *prefix, char comma) {
-    if (base < 2 || base > 32) {
-        return 0;
-    }
-
-    mp_uint_t num_digits = i->len * DIG_SIZE / log_base2_floor[base] + 1;
-    mp_uint_t num_commas = comma ? num_digits / 3: 0;
-    mp_uint_t prefix_len = prefix ? strlen(prefix) : 0;
-
-    return num_digits + num_commas + prefix_len + 2; // +1 for sign, +1 for null byte
-}
-
 #if 0
 this function is unused
 char *mpz_as_str(const mpz_t *i, mp_uint_t base) {
@@ -1678,7 +1649,7 @@ char *mpz_as_str(const mpz_t *i, mp_uint_t base) {
 }
 #endif
 
-// assumes enough space as calculated by mpz_as_str_size
+// assumes enough space as calculated by mp_int_format_size
 // returns length of string, not including null byte
 mp_uint_t mpz_as_str_inpl(const mpz_t *i, mp_uint_t base, const char *prefix, char base_char, char comma, char *str) {
     if (str == NULL || base < 2 || base > 32) {
diff --git a/py/mpz.h b/py/mpz.h
index 63ac772ff..55ef3e15f 100644
--- a/py/mpz.h
+++ b/py/mpz.h
@@ -127,6 +127,7 @@ void mpz_or_inpl(mpz_t *dest, const mpz_t *lhs, const mpz_t *rhs);
 void mpz_xor_inpl(mpz_t *dest, const mpz_t *lhs, const mpz_t *rhs);
 void mpz_divmod_inpl(mpz_t *dest_quo, mpz_t *dest_rem, const mpz_t *lhs, const mpz_t *rhs);
 
+static inline size_t mpz_max_num_bits(const mpz_t *z) { return z->len * MPZ_DIG_SIZE; }
 mp_int_t mpz_hash(const mpz_t *z);
 bool mpz_as_int_checked(const mpz_t *z, mp_int_t *value);
 bool mpz_as_uint_checked(const mpz_t *z, mp_uint_t *value);
diff --git a/py/obj.c b/py/obj.c
index d6ce3dae6..72b7a216b 100644
--- a/py/obj.c
+++ b/py/obj.c
@@ -233,8 +233,7 @@ mp_int_t mp_obj_get_int(mp_const_obj_t arg) {
         return mp_obj_int_get_checked(arg);
     } else {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "can't convert to int"));
+            mp_raise_msg(&mp_type_TypeError, "can't convert to int");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "can't convert %s to int", mp_obj_get_type_str(arg)));
@@ -282,8 +281,7 @@ mp_float_t mp_obj_get_float(mp_obj_t arg) {
         return mp_obj_float_get(arg);
     } else {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "can't convert to float"));
+            mp_raise_msg(&mp_type_TypeError, "can't convert to float");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "can't convert %s to float", mp_obj_get_type_str(arg)));
@@ -312,8 +310,7 @@ void mp_obj_get_complex(mp_obj_t arg, mp_float_t *real, mp_float_t *imag) {
         mp_obj_complex_get(arg, real, imag);
     } else {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "can't convert to complex"));
+            mp_raise_msg(&mp_type_TypeError, "can't convert to complex");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "can't convert %s to complex", mp_obj_get_type_str(arg)));
@@ -331,8 +328,7 @@ void mp_obj_get_array(mp_obj_t o, mp_uint_t *len, mp_obj_t **items) {
         mp_obj_list_get(o, len, items);
     } else {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "expected tuple/list"));
+            mp_raise_msg(&mp_type_TypeError, "expected tuple/list");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "object '%s' is not a tuple or list", mp_obj_get_type_str(o)));
@@ -346,8 +342,7 @@ void mp_obj_get_array_fixed_n(mp_obj_t o, mp_uint_t len, mp_obj_t **items) {
     mp_obj_get_array(o, &seq_len, items);
     if (seq_len != len) {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError,
-                "tuple/list has wrong length"));
+            mp_raise_msg(&mp_type_ValueError, "tuple/list has wrong length");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
                 "requested length %d but object has length %d", (int)len, (int)seq_len));
@@ -362,8 +357,7 @@ mp_uint_t mp_get_index(const mp_obj_type_t *type, mp_uint_t len, mp_obj_t index,
         i = MP_OBJ_SMALL_INT_VALUE(index);
     } else if (!mp_obj_get_int_maybe(index, &i)) {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "indices must be integers"));
+            mp_raise_msg(&mp_type_TypeError, "indices must be integers");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "%q indices must be integers, not %s",
@@ -383,7 +377,7 @@ mp_uint_t mp_get_index(const mp_obj_type_t *type, mp_uint_t len, mp_obj_t index,
     } else {
         if (i < 0 || (mp_uint_t)i >= len) {
             if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_IndexError, "index out of range"));
+                mp_raise_msg(&mp_type_IndexError, "index out of range");
             } else {
                 nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_IndexError,
                     "%q index out of range", type->name));
@@ -416,8 +410,7 @@ mp_obj_t mp_obj_len(mp_obj_t o_in) {
     mp_obj_t len = mp_obj_len_maybe(o_in);
     if (len == MP_OBJ_NULL) {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "object has no len"));
+            mp_raise_msg(&mp_type_TypeError, "object has no len");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "object of type '%s' has no len()", mp_obj_get_type_str(o_in)));
@@ -458,8 +451,7 @@ mp_obj_t mp_obj_subscr(mp_obj_t base, mp_obj_t index, mp_obj_t value) {
     }
     if (value == MP_OBJ_NULL) {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "object does not support item deletion"));
+            mp_raise_msg(&mp_type_TypeError, "object does not support item deletion");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "'%s' object does not support item deletion", mp_obj_get_type_str(base)));
@@ -474,8 +466,7 @@ mp_obj_t mp_obj_subscr(mp_obj_t base, mp_obj_t index, mp_obj_t value) {
         }
     } else {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "object does not support item assignment"));
+            mp_raise_msg(&mp_type_TypeError, "object does not support item assignment");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "'%s' object does not support item assignment", mp_obj_get_type_str(base)));
@@ -504,7 +495,7 @@ bool mp_get_buffer(mp_obj_t obj, mp_buffer_info_t *bufinfo, mp_uint_t flags) {
 
 void mp_get_buffer_raise(mp_obj_t obj, mp_buffer_info_t *bufinfo, mp_uint_t flags) {
     if (!mp_get_buffer(obj, bufinfo, flags)) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "object with buffer protocol required"));
+        mp_raise_msg(&mp_type_TypeError, "object with buffer protocol required");
     }
 }
 
diff --git a/py/objarray.c b/py/objarray.c
index 2cd0fef6b..8e1d32f0f 100644
--- a/py/objarray.c
+++ b/py/objarray.c
@@ -95,7 +95,7 @@ STATIC void array_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t
 STATIC mp_obj_array_t *array_new(char typecode, mp_uint_t n) {
     int typecode_size = mp_binary_get_size('@', typecode, NULL);
     if (typecode_size == 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "bad typecode"));
+        mp_raise_msg(&mp_type_ValueError, "bad typecode");
     }
     mp_obj_array_t *o = m_new_obj(mp_obj_array_t);
     #if MICROPY_PY_BUILTINS_BYTEARRAY && MICROPY_PY_ARRAY
@@ -395,7 +395,7 @@ STATIC mp_obj_t array_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value
                     mp_obj_array_t *src_slice = MP_OBJ_TO_PTR(value);
                     if (item_sz != mp_binary_get_size('@', src_slice->typecode & TYPECODE_MASK, NULL)) {
                     compat_error:
-                        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "lhs and rhs should be compatible"));
+                        mp_raise_msg(&mp_type_ValueError, "lhs and rhs should be compatible");
                     }
                     src_len = src_slice->len;
                     src_items = src_slice->items;
diff --git a/py/objcomplex.c b/py/objcomplex.c
index 5da655eb3..96be25255 100644
--- a/py/objcomplex.c
+++ b/py/objcomplex.c
@@ -197,7 +197,7 @@ mp_obj_t mp_obj_complex_binary_op(mp_uint_t op, mp_float_t lhs_real, mp_float_t
         case MP_BINARY_OP_INPLACE_TRUE_DIVIDE:
             if (rhs_imag == 0) {
                 if (rhs_real == 0) {
-                    nlr_raise(mp_obj_new_exception_msg(&mp_type_ZeroDivisionError, "complex division by zero"));
+                    mp_raise_msg(&mp_type_ZeroDivisionError, "complex division by zero");
                 }
                 lhs_real /= rhs_real;
                 lhs_imag /= rhs_real;
@@ -226,7 +226,7 @@ mp_obj_t mp_obj_complex_binary_op(mp_uint_t op, mp_float_t lhs_real, mp_float_t
                     lhs_real = 1;
                     rhs_real = 0;
                 } else {
-                    nlr_raise(mp_obj_new_exception_msg(&mp_type_ZeroDivisionError, "0.0 to a complex power"));
+                    mp_raise_msg(&mp_type_ZeroDivisionError, "0.0 to a complex power");
                 }
             } else {
                 mp_float_t ln1 = MICROPY_FLOAT_C_FUN(log)(abs1);
diff --git a/py/objdict.c b/py/objdict.c
index 7a74557dc..4942d3779 100644
--- a/py/objdict.c
+++ b/py/objdict.c
@@ -162,7 +162,7 @@ mp_obj_t mp_obj_dict_get(mp_obj_t self_in, mp_obj_t index) {
     mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
     mp_map_elem_t *elem = mp_map_lookup(&self->map, index, MP_MAP_LOOKUP);
     if (elem == NULL) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_KeyError, "<value>"));
+        nlr_raise(mp_obj_new_exception_arg1(&mp_type_KeyError, index));
     } else {
         return elem->value;
     }
@@ -178,7 +178,7 @@ STATIC mp_obj_t dict_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
         mp_obj_dict_t *self = MP_OBJ_TO_PTR(self_in);
         mp_map_elem_t *elem = mp_map_lookup(&self->map, index, MP_MAP_LOOKUP);
         if (elem == NULL) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_KeyError, "<value>"));
+            nlr_raise(mp_obj_new_exception_arg1(&mp_type_KeyError, index));
         } else {
             return elem->value;
         }
@@ -250,15 +250,16 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(dict_copy_obj, dict_copy);
 // this is a classmethod
 STATIC mp_obj_t dict_fromkeys(size_t n_args, const mp_obj_t *args) {
     mp_obj_t iter = mp_getiter(args[1]);
-    mp_obj_t len = mp_obj_len_maybe(iter);
     mp_obj_t value = mp_const_none;
     mp_obj_t next = MP_OBJ_NULL;
-    mp_obj_t self_out;
 
     if (n_args > 2) {
         value = args[2];
     }
 
+    // optimisation to allocate result based on len of argument
+    mp_obj_t self_out;
+    mp_obj_t len = mp_obj_len_maybe(args[1]);
     if (len == MP_OBJ_NULL) {
         /* object's type doesn't have a __len__ slot */
         self_out = mp_obj_new_dict(0);
@@ -282,7 +283,7 @@ STATIC mp_obj_t dict_get_helper(mp_map_t *self, mp_obj_t key, mp_obj_t deflt, mp
     if (elem == NULL || elem->value == MP_OBJ_NULL) {
         if (deflt == MP_OBJ_NULL) {
             if (lookup_kind == MP_MAP_LOOKUP_REMOVE_IF_FOUND) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_KeyError, "<value>"));
+                nlr_raise(mp_obj_new_exception_arg1(&mp_type_KeyError, key));
             } else {
                 value = mp_const_none;
             }
@@ -342,7 +343,7 @@ STATIC mp_obj_t dict_popitem(mp_obj_t self_in) {
     mp_uint_t cur = 0;
     mp_map_elem_t *next = dict_iter_next(self, &cur);
     if (next == NULL) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_KeyError, "popitem(): dictionary is empty"));
+        mp_raise_msg(&mp_type_KeyError, "popitem(): dictionary is empty");
     }
     self->map.used--;
     mp_obj_t items[] = {next->key, next->value};
@@ -384,9 +385,7 @@ STATIC mp_obj_t dict_update(size_t n_args, const mp_obj_t *args, mp_map_t *kwarg
                 if (key == MP_OBJ_STOP_ITERATION
                     || value == MP_OBJ_STOP_ITERATION
                     || stop != MP_OBJ_STOP_ITERATION) {
-                    nlr_raise(mp_obj_new_exception_msg(
-                                 &mp_type_ValueError,
-                                 "dictionary update sequence has the wrong length"));
+                    mp_raise_msg(&mp_type_ValueError, "dictionary update sequence has the wrong length");
                 } else {
                     mp_map_lookup(&self->map, key, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = value;
                 }
diff --git a/py/objfloat.c b/py/objfloat.c
index 85b8b1386..73d07feac 100644
--- a/py/objfloat.c
+++ b/py/objfloat.c
@@ -198,7 +198,7 @@ mp_obj_t mp_obj_float_binary_op(mp_uint_t op, mp_float_t lhs_val, mp_obj_t rhs_i
         case MP_BINARY_OP_INPLACE_FLOOR_DIVIDE:
             if (rhs_val == 0) {
                 zero_division_error:
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_ZeroDivisionError, "division by zero"));
+                mp_raise_msg(&mp_type_ZeroDivisionError, "division by zero");
             }
             // Python specs require that x == (x//y)*y + (x%y) so we must
             // call divmod to compute the correct floor division, which
diff --git a/py/objgenerator.c b/py/objgenerator.c
index 8c32a3649..cbef9fea3 100644
--- a/py/objgenerator.c
+++ b/py/objgenerator.c
@@ -105,7 +105,7 @@ mp_vm_return_kind_t mp_obj_gen_resume(mp_obj_t self_in, mp_obj_t send_value, mp_
     }
     if (self->code_state.sp == self->code_state.state - 1) {
         if (send_value != mp_const_none) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "can't send non-None value to a just-started generator"));
+            mp_raise_msg(&mp_type_TypeError, "can't send non-None value to a just-started generator");
         }
     } else {
         *self->code_state.sp = send_value;
@@ -157,7 +157,7 @@ STATIC mp_obj_t gen_resume_and_raise(mp_obj_t self_in, mp_obj_t send_value, mp_o
 
         case MP_VM_RETURN_YIELD:
             if (throw_value != MP_OBJ_NULL && mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(mp_obj_get_type(throw_value)), MP_OBJ_FROM_PTR(&mp_type_GeneratorExit))) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_RuntimeError, "generator ignored GeneratorExit"));
+                mp_raise_msg(&mp_type_RuntimeError, "generator ignored GeneratorExit");
             }
             return ret;
 
@@ -209,7 +209,7 @@ STATIC mp_obj_t gen_instance_close(mp_obj_t self_in) {
     mp_obj_t ret;
     switch (mp_obj_gen_resume(self_in, mp_const_none, MP_OBJ_FROM_PTR(&mp_const_GeneratorExit_obj), &ret)) {
         case MP_VM_RETURN_YIELD:
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_RuntimeError, "generator ignored GeneratorExit"));
+            mp_raise_msg(&mp_type_RuntimeError, "generator ignored GeneratorExit");
 
         // Swallow StopIteration & GeneratorExit (== successful close), and re-raise any other
         case MP_VM_RETURN_EXCEPTION:
diff --git a/py/objint.c b/py/objint.c
index 9f948a145..f8988d6c9 100644
--- a/py/objint.c
+++ b/py/objint.c
@@ -133,8 +133,8 @@ void mp_obj_int_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t
     // enough, a dynamic one will be allocated.
     char stack_buf[sizeof(mp_int_t) * 4];
     char *buf = stack_buf;
-    mp_uint_t buf_size = sizeof(stack_buf);
-    mp_uint_t fmt_size;
+    size_t buf_size = sizeof(stack_buf);
+    size_t fmt_size;
 
     char *str = mp_obj_int_formatted(&buf, &buf_size, &fmt_size, self_in, 10, NULL, '\0', '\0');
     mp_print_str(print, str);
@@ -162,14 +162,14 @@ STATIC const uint8_t log_base2_floor[] = {
     4, 4, 4, 5
 };
 
-STATIC uint int_as_str_size_formatted(uint base, const char *prefix, char comma) {
+size_t mp_int_format_size(size_t num_bits, int base, const char *prefix, char comma) {
     if (base < 2 || base > 32) {
         return 0;
     }
 
-    uint num_digits = sizeof(fmt_int_t) * 8 / log_base2_floor[base] + 1;
-    uint num_commas = comma ? num_digits / 3: 0;
-    uint prefix_len = prefix ? strlen(prefix) : 0;
+    size_t num_digits = num_bits / log_base2_floor[base] + 1;
+    size_t num_commas = comma ? num_digits / 3 : 0;
+    size_t prefix_len = prefix ? strlen(prefix) : 0;
     return num_digits + num_commas + prefix_len + 2; // +1 for sign, +1 for null byte
 }
 
@@ -180,7 +180,7 @@ STATIC uint int_as_str_size_formatted(uint base, const char *prefix, char comma)
 //
 // The resulting formatted string will be returned from this function and the
 // formatted size will be in *fmt_size.
-char *mp_obj_int_formatted(char **buf, mp_uint_t *buf_size, mp_uint_t *fmt_size, mp_const_obj_t self_in,
+char *mp_obj_int_formatted(char **buf, size_t *buf_size, size_t *fmt_size, mp_const_obj_t self_in,
                            int base, const char *prefix, char base_char, char comma) {
     fmt_int_t num;
     if (MP_OBJ_IS_SMALL_INT(self_in)) {
@@ -211,7 +211,7 @@ char *mp_obj_int_formatted(char **buf, mp_uint_t *buf_size, mp_uint_t *fmt_size,
         sign = '-';
     }
 
-    uint needed_size = int_as_str_size_formatted(base, prefix, comma);
+    size_t needed_size = mp_int_format_size(sizeof(fmt_int_t) * 8, base, prefix, comma);
     if (needed_size > *buf_size) {
         *buf = m_new(char, needed_size);
         *buf_size = needed_size;
@@ -294,19 +294,19 @@ mp_obj_t mp_obj_int_binary_op(mp_uint_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
 
 // This is called only with strings whose value doesn't fit in SMALL_INT
 mp_obj_t mp_obj_new_int_from_str_len(const char **str, mp_uint_t len, bool neg, mp_uint_t base) {
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_OverflowError, "long int not supported in this build"));
+    mp_raise_msg(&mp_type_OverflowError, "long int not supported in this build");
     return mp_const_none;
 }
 
 // This is called when an integer larger than a SMALL_INT is needed (although val might still fit in a SMALL_INT)
 mp_obj_t mp_obj_new_int_from_ll(long long val) {
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_OverflowError, "small int overflow"));
+    mp_raise_msg(&mp_type_OverflowError, "small int overflow");
     return mp_const_none;
 }
 
 // This is called when an integer larger than a SMALL_INT is needed (although val might still fit in a SMALL_INT)
 mp_obj_t mp_obj_new_int_from_ull(unsigned long long val) {
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_OverflowError, "small int overflow"));
+    mp_raise_msg(&mp_type_OverflowError, "small int overflow");
     return mp_const_none;
 }
 
@@ -316,7 +316,7 @@ mp_obj_t mp_obj_new_int_from_uint(mp_uint_t value) {
     if ((value & ~MP_SMALL_INT_POSITIVE_MASK) == 0) {
         return MP_OBJ_NEW_SMALL_INT(value);
     }
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_OverflowError, "small int overflow"));
+    mp_raise_msg(&mp_type_OverflowError, "small int overflow");
     return mp_const_none;
 }
 
@@ -342,7 +342,7 @@ mp_obj_t mp_obj_new_int(mp_int_t value) {
     if (MP_SMALL_INT_FITS(value)) {
         return MP_OBJ_NEW_SMALL_INT(value);
     }
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_OverflowError, "small int overflow"));
+    mp_raise_msg(&mp_type_OverflowError, "small int overflow");
     return mp_const_none;
 }
 
diff --git a/py/objint.h b/py/objint.h
index c79eb874a..6e627f1bd 100644
--- a/py/objint.h
+++ b/py/objint.h
@@ -50,13 +50,15 @@ typedef enum {
 mp_fp_as_int_class_t mp_classify_fp_as_int(mp_float_t val);
 #endif // MICROPY_PY_BUILTINS_FLOAT
 
+size_t mp_int_format_size(size_t num_bits, int base, const char *prefix, char comma);
+
 void mp_obj_int_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind);
-char *mp_obj_int_formatted(char **buf, mp_uint_t *buf_size, mp_uint_t *fmt_size, mp_const_obj_t self_in,
+char *mp_obj_int_formatted(char **buf, size_t *buf_size, size_t *fmt_size, mp_const_obj_t self_in,
                            int base, const char *prefix, char base_char, char comma);
-char *mp_obj_int_formatted_impl(char **buf, mp_uint_t *buf_size, mp_uint_t *fmt_size, mp_const_obj_t self_in,
+char *mp_obj_int_formatted_impl(char **buf, size_t *buf_size, size_t *fmt_size, mp_const_obj_t self_in,
                                 int base, const char *prefix, char base_char, char comma);
 mp_int_t mp_obj_int_hash(mp_obj_t self_in);
-void mp_obj_int_to_bytes_impl(mp_obj_t self_in, bool big_endian, mp_uint_t len, byte *buf);
+void mp_obj_int_to_bytes_impl(mp_obj_t self_in, bool big_endian, size_t len, byte *buf);
 int mp_obj_int_sign(mp_obj_t self_in);
 mp_obj_t mp_obj_int_abs(mp_obj_t self_in);
 mp_obj_t mp_obj_int_unary_op(mp_uint_t op, mp_obj_t o_in);
diff --git a/py/objint_longlong.c b/py/objint_longlong.c
index f10e46447..b051cfbe6 100644
--- a/py/objint_longlong.c
+++ b/py/objint_longlong.c
@@ -53,7 +53,7 @@
 const mp_obj_int_t mp_maxsize_obj = {{&mp_type_int}, MP_SSIZE_MAX};
 #endif
 
-void mp_obj_int_to_bytes_impl(mp_obj_t self_in, bool big_endian, mp_uint_t len, byte *buf) {
+void mp_obj_int_to_bytes_impl(mp_obj_t self_in, bool big_endian, size_t len, byte *buf) {
     assert(MP_OBJ_IS_TYPE(self_in, &mp_type_int));
     mp_obj_int_t *self = self_in;
     long long val = self->val;
diff --git a/py/objint_mpz.c b/py/objint_mpz.c
index 3a30eb9d9..0a1d68598 100644
--- a/py/objint_mpz.c
+++ b/py/objint_mpz.c
@@ -90,12 +90,12 @@ STATIC mp_obj_int_t *mp_obj_int_new_mpz(void) {
 // formatted size will be in *fmt_size.
 //
 // This particular routine should only be called for the mpz representation of the int.
-char *mp_obj_int_formatted_impl(char **buf, mp_uint_t *buf_size, mp_uint_t *fmt_size, mp_const_obj_t self_in,
+char *mp_obj_int_formatted_impl(char **buf, size_t *buf_size, size_t *fmt_size, mp_const_obj_t self_in,
                                 int base, const char *prefix, char base_char, char comma) {
     assert(MP_OBJ_IS_TYPE(self_in, &mp_type_int));
     const mp_obj_int_t *self = MP_OBJ_TO_PTR(self_in);
 
-    mp_uint_t needed_size = mpz_as_str_size(&self->mpz, base, prefix, comma);
+    size_t needed_size = mp_int_format_size(mpz_max_num_bits(&self->mpz), base, prefix, comma);
     if (needed_size > *buf_size) {
         *buf = m_new(char, needed_size);
         *buf_size = needed_size;
@@ -107,7 +107,7 @@ char *mp_obj_int_formatted_impl(char **buf, mp_uint_t *buf_size, mp_uint_t *fmt_
     return str;
 }
 
-void mp_obj_int_to_bytes_impl(mp_obj_t self_in, bool big_endian, mp_uint_t len, byte *buf) {
+void mp_obj_int_to_bytes_impl(mp_obj_t self_in, bool big_endian, size_t len, byte *buf) {
     assert(MP_OBJ_IS_TYPE(self_in, &mp_type_int));
     mp_obj_int_t *self = MP_OBJ_TO_PTR(self_in);
     mpz_as_bytes(&self->mpz, big_endian, len, buf);
@@ -234,8 +234,7 @@ mp_obj_t mp_obj_int_binary_op(mp_uint_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
             case MP_BINARY_OP_INPLACE_FLOOR_DIVIDE: {
                 if (mpz_is_zero(zrhs)) {
                     zero_division_error:
-                    nlr_raise(mp_obj_new_exception_msg(&mp_type_ZeroDivisionError,
-                        "division by zero"));
+                    mp_raise_msg(&mp_type_ZeroDivisionError, "division by zero");
                 }
                 mpz_t rem; mpz_init_zero(&rem);
                 mpz_divmod_inpl(&res->mpz, &rem, zlhs, zrhs);
@@ -272,7 +271,7 @@ mp_obj_t mp_obj_int_binary_op(mp_uint_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
             case MP_BINARY_OP_INPLACE_RSHIFT: {
                 mp_int_t irhs = mp_obj_int_get_checked(rhs_in);
                 if (irhs < 0) {
-                    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "negative shift count"));
+                    mp_raise_msg(&mp_type_ValueError, "negative shift count");
                 }
                 if (op == MP_BINARY_OP_LSHIFT || op == MP_BINARY_OP_INPLACE_LSHIFT) {
                     mpz_shl_inpl(&res->mpz, zlhs, irhs);
@@ -398,7 +397,7 @@ mp_int_t mp_obj_int_get_checked(mp_const_obj_t self_in) {
             return value;
         } else {
             // overflow
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_OverflowError, "overflow converting long int to machine word"));
+            mp_raise_msg(&mp_type_OverflowError, "overflow converting long int to machine word");
         }
     }
 }
diff --git a/py/objlist.c b/py/objlist.c
index b5e8b9965..6d4a20a50 100644
--- a/py/objlist.c
+++ b/py/objlist.c
@@ -266,7 +266,7 @@ STATIC mp_obj_t list_pop(size_t n_args, const mp_obj_t *args) {
     mp_check_self(MP_OBJ_IS_TYPE(args[0], &mp_type_list));
     mp_obj_list_t *self = MP_OBJ_TO_PTR(args[0]);
     if (self->len == 0) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_IndexError, "pop from empty list"));
+        mp_raise_msg(&mp_type_IndexError, "pop from empty list");
     }
     mp_uint_t index = mp_get_index(self->base.type, self->len, n_args == 1 ? MP_OBJ_NEW_SMALL_INT(-1) : args[1], false);
     mp_obj_t ret = self->items[index];
diff --git a/py/objnamedtuple.c b/py/objnamedtuple.c
index 38cda1ad7..18931a16c 100644
--- a/py/objnamedtuple.c
+++ b/py/objnamedtuple.c
@@ -73,7 +73,7 @@ STATIC void namedtuple_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
     } else {
         // delete/store attribute
         // provide more detailed error message than we'd get by just returning
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_AttributeError, "can't set attribute"));
+        mp_raise_msg(&mp_type_AttributeError, "can't set attribute");
     }
 }
 
diff --git a/py/objobject.c b/py/objobject.c
index bba6f053e..b33dc491c 100644
--- a/py/objobject.c
+++ b/py/objobject.c
@@ -50,8 +50,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(object___init___obj, object___init__);
 
 STATIC mp_obj_t object___new__(mp_obj_t cls) {
     if (!MP_OBJ_IS_TYPE(cls, &mp_type_type) || !mp_obj_is_instance_type((mp_obj_type_t*)MP_OBJ_TO_PTR(cls))) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                    "__new__ arg must be a user-type"));
+        mp_raise_msg(&mp_type_TypeError, "__new__ arg must be a user-type");
     }
     mp_obj_t o = MP_OBJ_SENTINEL;
     mp_obj_t res = mp_obj_instance_make_new(MP_OBJ_TO_PTR(cls), 1, 0, &o);
diff --git a/py/objset.c b/py/objset.c
index 6b6f95f9b..fc124fcd8 100644
--- a/py/objset.c
+++ b/py/objset.c
@@ -68,7 +68,7 @@ STATIC void check_set(mp_obj_t o) {
     if (MP_OBJ_IS_TYPE(o, &mp_type_frozenset)) {
         // Mutable method called on frozenset; emulate CPython behavior, eg:
         // AttributeError: 'frozenset' object has no attribute 'add'
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_AttributeError, "'frozenset' has no such attribute"));
+        mp_raise_msg(&mp_type_AttributeError, "'frozenset' has no such attribute");
     }
     #endif
     mp_check_self(MP_OBJ_IS_TYPE(o, &mp_type_set));
@@ -389,7 +389,7 @@ STATIC mp_obj_t set_pop(mp_obj_t self_in) {
     mp_obj_set_t *self = MP_OBJ_TO_PTR(self_in);
     mp_obj_t obj = mp_set_remove_first(&self->set);
     if (obj == MP_OBJ_NULL) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_KeyError, "pop from an empty set"));
+        mp_raise_msg(&mp_type_KeyError, "pop from an empty set");
     }
     return obj;
 }
diff --git a/py/objstringio.c b/py/objstringio.c
index eb0cc4eb3..a430fca3b 100644
--- a/py/objstringio.c
+++ b/py/objstringio.c
@@ -30,22 +30,16 @@
 
 #include "py/nlr.h"
 #include "py/objstr.h"
+#include "py/objstringio.h"
 #include "py/runtime.h"
 #include "py/stream.h"
 
 #if MICROPY_PY_IO
 
-typedef struct _mp_obj_stringio_t {
-    mp_obj_base_t base;
-    vstr_t *vstr;
-    // StringIO has single pointer used for both reading and writing
-    mp_uint_t pos;
-} mp_obj_stringio_t;
-
 #if MICROPY_CPYTHON_COMPAT
 STATIC void check_stringio_is_open(const mp_obj_stringio_t *o) {
     if (o->vstr == NULL) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "I/O operation on closed file"));
+        mp_raise_msg(&mp_type_ValueError, "I/O operation on closed file");
     }
 }
 #else
@@ -156,7 +150,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(stringio___exit___obj, 4, 4, stringio
 STATIC mp_obj_stringio_t *stringio_new(const mp_obj_type_t *type) {
     mp_obj_stringio_t *o = m_new_obj(mp_obj_stringio_t);
     o->base.type = type;
-    o->vstr = vstr_new();
+    o->vstr = vstr_new(16);
     o->pos = 0;
     return o;
 }
diff --git a/py/objstringio.h b/py/objstringio.h
new file mode 100644
index 000000000..853bfb11b
--- /dev/null
+++ b/py/objstringio.h
@@ -0,0 +1,38 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef MICROPY_INCLUDED_PY_OBJSTRINGIO_H
+#define MICROPY_INCLUDED_PY_OBJSTRINGIO_H
+
+#include "py/obj.h"
+
+typedef struct _mp_obj_stringio_t {
+    mp_obj_base_t base;
+    vstr_t *vstr;
+    // StringIO has single pointer used for both reading and writing
+    mp_uint_t pos;
+} mp_obj_stringio_t;
+
+#endif // MICROPY_INCLUDED_PY_OBJSTRINGIO_H
diff --git a/py/objtype.c b/py/objtype.c
index 907308a75..8b46c5400 100644
--- a/py/objtype.c
+++ b/py/objtype.c
@@ -311,8 +311,7 @@ mp_obj_t mp_obj_instance_make_new(const mp_obj_type_t *self, size_t n_args, size
         }
         if (init_ret != mp_const_none) {
             if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                    "__init__() should return None"));
+                mp_raise_msg(&mp_type_TypeError, "__init__() should return None");
             } else {
                 nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                     "__init__() should return None, not '%s'", mp_obj_get_type_str(init_ret)));
@@ -508,7 +507,7 @@ STATIC void mp_obj_instance_load_attr(mp_obj_t self_in, qstr attr, mp_obj_t *des
             // the code.
             const mp_obj_t *proxy = mp_obj_property_get(member);
             if (proxy[0] == mp_const_none) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_AttributeError, "unreadable attribute"));
+                mp_raise_msg(&mp_type_AttributeError, "unreadable attribute");
             } else {
                 dest[0] = mp_call_function_n_kw(proxy[0], 1, 0, &self_in);
             }
@@ -710,8 +709,7 @@ mp_obj_t mp_obj_instance_call(mp_obj_t self_in, size_t n_args, size_t n_kw, cons
     mp_obj_t call = mp_obj_instance_get_call(self_in);
     if (call == MP_OBJ_NULL) {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "object not callable"));
+            mp_raise_msg(&mp_type_TypeError, "object not callable");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "'%s' object is not callable", mp_obj_get_type_str(self_in)));
@@ -793,7 +791,7 @@ STATIC mp_obj_t type_make_new(const mp_obj_type_t *type_in, size_t n_args, size_
             return mp_obj_new_type(mp_obj_str_get_qstr(args[0]), args[1], args[2]);
 
         default:
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "type takes 1 or 3 arguments"));
+            mp_raise_msg(&mp_type_TypeError, "type takes 1 or 3 arguments");
     }
 }
 
@@ -804,7 +802,7 @@ STATIC mp_obj_t type_call(mp_obj_t self_in, size_t n_args, size_t n_kw, const mp
 
     if (self->make_new == NULL) {
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "cannot create instance"));
+            mp_raise_msg(&mp_type_TypeError, "cannot create instance");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "cannot create '%q' instances", self->name));
@@ -892,8 +890,7 @@ mp_obj_t mp_obj_new_type(qstr name, mp_obj_t bases_tuple, mp_obj_t locals_dict)
         // TODO: Verify with CPy, tested on function type
         if (t->make_new == NULL) {
             if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                    "type is not an acceptable base type"));
+                mp_raise_msg(&mp_type_TypeError, "type is not an acceptable base type");
             } else {
                 nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                     "type '%q' is not an acceptable base type", t->name));
@@ -927,7 +924,7 @@ mp_obj_t mp_obj_new_type(qstr name, mp_obj_t bases_tuple, mp_obj_t locals_dict)
     const mp_obj_type_t *native_base;
     uint num_native_bases = instance_count_native_bases(o, &native_base);
     if (num_native_bases > 1) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "multiple bases have instance lay-out conflict"));
+        mp_raise_msg(&mp_type_TypeError, "multiple bases have instance lay-out conflict");
     }
 
     mp_map_t *locals_map = &o->locals_dict->map;
@@ -1074,7 +1071,7 @@ STATIC mp_obj_t mp_obj_is_subclass(mp_obj_t object, mp_obj_t classinfo) {
     } else if (MP_OBJ_IS_TYPE(classinfo, &mp_type_tuple)) {
         mp_obj_tuple_get(classinfo, &len, &items);
     } else {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "issubclass() arg 2 must be a class or a tuple of classes"));
+        mp_raise_msg(&mp_type_TypeError, "issubclass() arg 2 must be a class or a tuple of classes");
     }
 
     for (uint i = 0; i < len; i++) {
@@ -1088,7 +1085,7 @@ STATIC mp_obj_t mp_obj_is_subclass(mp_obj_t object, mp_obj_t classinfo) {
 
 STATIC mp_obj_t mp_builtin_issubclass(mp_obj_t object, mp_obj_t classinfo) {
     if (!MP_OBJ_IS_TYPE(object, &mp_type_type)) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "issubclass() arg 1 must be a class"));
+        mp_raise_msg(&mp_type_TypeError, "issubclass() arg 1 must be a class");
     }
     return mp_obj_is_subclass(object, classinfo);
 }
diff --git a/py/parsenum.c b/py/parsenum.c
index 83a6abd20..1010ad305 100644
--- a/py/parsenum.c
+++ b/py/parsenum.c
@@ -27,7 +27,7 @@
 #include <stdbool.h>
 #include <stdlib.h>
 
-#include "py/nlr.h"
+#include "py/runtime.h"
 #include "py/parsenumbase.h"
 #include "py/parsenum.h"
 #include "py/smallint.h"
@@ -55,7 +55,7 @@ mp_obj_t mp_parse_num_integer(const char *restrict str_, size_t len, int base, m
     // check radix base
     if ((base != 0 && base < 2) || base > 36) {
         // this won't be reached if lex!=NULL
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "int() arg 2 must be >= 2 and <= 36"));
+        mp_raise_msg(&mp_type_ValueError, "int() arg 2 must be >= 2 and <= 36");
     }
 
     // skip leading space
diff --git a/py/py.mk b/py/py.mk
index 741ad52f9..ab07bbbde 100644
--- a/py/py.mk
+++ b/py/py.mk
@@ -229,6 +229,7 @@ PY_O_BASENAME = \
 	../extmod/vfs_fat_file.o \
 	../extmod/vfs_fat_lexer.o \
 	../extmod/vfs_fat_misc.o \
+	../extmod/utime_mphal.o \
 	../extmod/moduos_dupterm.o \
 	../lib/embed/abort_.o \
 	../lib/utils/printf.o \
@@ -236,6 +237,10 @@ PY_O_BASENAME = \
 # prepend the build destination prefix to the py object files
 PY_O = $(addprefix $(PY_BUILD)/, $(PY_O_BASENAME))
 
+ifneq ($(FROZEN_DIR),)
+PY_O += $(BUILD)/$(BUILD)/frozen.o
+endif
+
 # Sources that may contain qstrings
 SRC_QSTR_IGNORE = nlr% emitnx% emitnthumb% emitnarm%
 SRC_QSTR = $(SRC_MOD) $(addprefix py/,$(filter-out $(SRC_QSTR_IGNORE),$(PY_O_BASENAME:.o=.c)) emitnative.c)
diff --git a/py/runtime.c b/py/runtime.c
index 003c9f8b4..6eda77ee9 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -138,8 +138,7 @@ mp_obj_t mp_load_global(qstr qst) {
         elem = mp_map_lookup((mp_map_t*)&mp_module_builtins_globals.map, MP_OBJ_NEW_QSTR(qst), MP_MAP_LOOKUP);
         if (elem == NULL) {
             if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_NameError,
-                    "name not defined"));
+                mp_raise_msg(&mp_type_NameError, "name not defined");
             } else {
                 nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_NameError,
                     "name '%q' is not defined", qst));
@@ -230,8 +229,7 @@ mp_obj_t mp_unary_op(mp_uint_t op, mp_obj_t arg) {
             }
         }
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "unsupported type for operator"));
+            mp_raise_msg(&mp_type_TypeError, "unsupported type for operator");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "unsupported type for %q: '%s'",
@@ -323,7 +321,7 @@ mp_obj_t mp_binary_op(mp_uint_t op, mp_obj_t lhs, mp_obj_t rhs) {
                 case MP_BINARY_OP_INPLACE_LSHIFT: {
                     if (rhs_val < 0) {
                         // negative shift not allowed
-                        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "negative shift count"));
+                        mp_raise_msg(&mp_type_ValueError, "negative shift count");
                     } else if (rhs_val >= (mp_int_t)BITS_PER_WORD || lhs_val > (MP_SMALL_INT_MAX >> rhs_val) || lhs_val < (MP_SMALL_INT_MIN >> rhs_val)) {
                         // left-shift will overflow, so use higher precision integer
                         lhs = mp_obj_new_int_from_ll(lhs_val);
@@ -338,7 +336,7 @@ mp_obj_t mp_binary_op(mp_uint_t op, mp_obj_t lhs, mp_obj_t rhs) {
                 case MP_BINARY_OP_INPLACE_RSHIFT:
                     if (rhs_val < 0) {
                         // negative shift not allowed
-                        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "negative shift count"));
+                        mp_raise_msg(&mp_type_ValueError, "negative shift count");
                     } else {
                         // standard precision is enough for right-shift
                         if (rhs_val >= (mp_int_t)BITS_PER_WORD) {
@@ -414,7 +412,7 @@ mp_obj_t mp_binary_op(mp_uint_t op, mp_obj_t lhs, mp_obj_t rhs) {
                         lhs = mp_obj_new_float(lhs_val);
                         goto generic_binary_op;
                         #else
-                        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "negative power with no float support"));
+                        mp_raise_msg(&mp_type_ValueError, "negative power with no float support");
                         #endif
                     } else {
                         mp_int_t ans = 1;
@@ -515,8 +513,7 @@ mp_obj_t mp_binary_op(mp_uint_t op, mp_obj_t lhs, mp_obj_t rhs) {
         }
 
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                "object not iterable"));
+            mp_raise_msg(&mp_type_TypeError, "object not iterable");
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                 "'%s' object is not iterable", mp_obj_get_type_str(rhs)));
@@ -538,8 +535,7 @@ generic_binary_op:
 
 unsupported_op:
     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-            "unsupported type for operator"));
+        mp_raise_msg(&mp_type_TypeError, "unsupported type for operator");
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
             "unsupported types for %q: '%s', '%s'",
@@ -547,7 +543,7 @@ unsupported_op:
     }
 
 zero_division:
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ZeroDivisionError, "division by zero"));
+    mp_raise_msg(&mp_type_ZeroDivisionError, "division by zero");
 }
 
 mp_obj_t mp_call_function_0(mp_obj_t fun) {
@@ -581,8 +577,7 @@ mp_obj_t mp_call_function_n_kw(mp_obj_t fun_in, mp_uint_t n_args, mp_uint_t n_kw
     }
 
     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-            "object not callable"));
+        mp_raise_msg(&mp_type_TypeError, "object not callable");
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
             "'%s' object is not callable", mp_obj_get_type_str(fun_in)));
@@ -813,16 +808,14 @@ void mp_unpack_sequence(mp_obj_t seq_in, mp_uint_t num, mp_obj_t *items) {
 
 too_short:
     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError,
-            "wrong number of values to unpack"));
+        mp_raise_msg(&mp_type_ValueError, "wrong number of values to unpack");
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
             "need more than %d values to unpack", (int)seq_len));
     }
 too_long:
     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError,
-            "wrong number of values to unpack"));
+        mp_raise_msg(&mp_type_ValueError, "wrong number of values to unpack");
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
             "too many values to unpack (expected %d)", (int)num));
@@ -888,8 +881,7 @@ void mp_unpack_ex(mp_obj_t seq_in, mp_uint_t num_in, mp_obj_t *items) {
 
 too_short:
     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError,
-            "wrong number of values to unpack"));
+        mp_raise_msg(&mp_type_ValueError, "wrong number of values to unpack");
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
             "need more than %d values to unpack", (int)seq_len));
@@ -928,8 +920,7 @@ STATIC mp_obj_t checked_fun_call(mp_obj_t self_in, size_t n_args, size_t n_kw, c
         const mp_obj_type_t *arg0_type = mp_obj_get_type(args[0]);
         if (arg0_type != self->type) {
             if (MICROPY_ERROR_REPORTING != MICROPY_ERROR_REPORTING_DETAILED) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                    "argument has wrong type"));
+                mp_raise_msg(&mp_type_TypeError, "argument has wrong type");
             } else {
                 nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                     "argument should be a '%q' not a '%q'", self->type->name, arg0_type->name));
@@ -1045,8 +1036,7 @@ void mp_load_method(mp_obj_t base, qstr attr, mp_obj_t *dest) {
     if (dest[0] == MP_OBJ_NULL) {
         // no attribute/method called attr
         if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-            nlr_raise(mp_obj_new_exception_msg(&mp_type_AttributeError,
-                "no such attribute"));
+            mp_raise_msg(&mp_type_AttributeError, "no such attribute");
         } else {
             // following CPython, we give a more detailed error message for type objects
             if (MP_OBJ_IS_TYPE(base, &mp_type_type)) {
@@ -1074,8 +1064,7 @@ void mp_store_attr(mp_obj_t base, qstr attr, mp_obj_t value) {
         }
     }
     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_AttributeError,
-            "no such attribute"));
+        mp_raise_msg(&mp_type_AttributeError, "no such attribute");
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_AttributeError,
             "'%s' object has no attribute '%q'",
@@ -1105,8 +1094,7 @@ mp_obj_t mp_getiter(mp_obj_t o_in) {
 
     // object not iterable
     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-            "object not iterable"));
+        mp_raise_msg(&mp_type_TypeError, "object not iterable");
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
             "'%s' object is not iterable", mp_obj_get_type_str(o_in)));
@@ -1128,8 +1116,7 @@ mp_obj_t mp_iternext_allow_raise(mp_obj_t o_in) {
             return mp_call_method_n_kw(0, 0, dest);
         } else {
             if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                    "object not an iterator"));
+                mp_raise_msg(&mp_type_TypeError, "object not an iterator");
             } else {
                 nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                     "'%s' object is not an iterator", mp_obj_get_type_str(o_in)));
@@ -1165,8 +1152,7 @@ mp_obj_t mp_iternext(mp_obj_t o_in) {
             }
         } else {
             if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
-                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
-                    "object not an iterator"));
+                mp_raise_msg(&mp_type_TypeError, "object not an iterator");
             } else {
                 nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                     "'%s' object is not an iterator", mp_obj_get_type_str(o_in)));
@@ -1384,8 +1370,7 @@ void *m_malloc_fail(size_t num_bytes) {
         // dummy
     #if MICROPY_ENABLE_GC
     } else if (gc_is_locked()) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_MemoryError,
-                                           "memory allocation failed, heap is locked"));
+        mp_raise_msg(&mp_type_MemoryError, "memory allocation failed, heap is locked");
     #endif
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_MemoryError,
diff --git a/py/sequence.c b/py/sequence.c
index 239f1b2cc..0acdd25be 100644
--- a/py/sequence.c
+++ b/py/sequence.c
@@ -235,7 +235,7 @@ mp_obj_t mp_seq_index_obj(const mp_obj_t *items, mp_uint_t len, mp_uint_t n_args
         }
     }
 
-    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "object not in sequence"));
+    mp_raise_msg(&mp_type_ValueError, "object not in sequence");
 }
 
 mp_obj_t mp_seq_count_obj(const mp_obj_t *items, mp_uint_t len, mp_obj_t value) {
diff --git a/py/stream.c b/py/stream.c
index 5610faf74..cc8a63ac2 100644
--- a/py/stream.c
+++ b/py/stream.c
@@ -101,7 +101,7 @@ const mp_stream_p_t *mp_get_stream_raise(mp_obj_t self_in, int flags) {
         || ((flags & MP_STREAM_OP_WRITE) && stream_p->write == NULL)
         || ((flags & MP_STREAM_OP_IOCTL) && stream_p->ioctl == NULL)) {
         // CPython: io.UnsupportedOperation, OSError subclass
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "stream operation not supported"));
+        mp_raise_msg(&mp_type_OSError, "stream operation not supported");
     }
     return stream_p;
 }
diff --git a/py/vstr.c b/py/vstr.c
index 5096475f1..6a91552b5 100644
--- a/py/vstr.c
+++ b/py/vstr.c
@@ -74,20 +74,8 @@ void vstr_clear(vstr_t *vstr) {
     vstr->buf = NULL;
 }
 
-vstr_t *vstr_new(void) {
+vstr_t *vstr_new(size_t alloc) {
     vstr_t *vstr = m_new_obj(vstr_t);
-    if (vstr == NULL) {
-        return NULL;
-    }
-    vstr_init(vstr, 16);
-    return vstr;
-}
-
-vstr_t *vstr_new_size(size_t alloc) {
-    vstr_t *vstr = m_new_obj(vstr_t);
-    if (vstr == NULL) {
-        return NULL;
-    }
     vstr_init(vstr, alloc);
     return vstr;
 }
diff --git a/qemu-arm/Makefile b/qemu-arm/Makefile
index 31ba6baa2..9159f97e5 100644
--- a/qemu-arm/Makefile
+++ b/qemu-arm/Makefile
@@ -40,19 +40,28 @@ SRC_C = \
 SRC_TEST_C = \
 	test_main.c \
 
+STM_SRC_C = $(addprefix stmhal/,\
+	pybstdio.c \
+	)
+
 SRC_S = \
 
 OBJ =
 OBJ += $(PY_O)
 OBJ += $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_S:.s=.o))
+OBJ += $(addprefix $(BUILD)/, $(STM_SRC_C:.c=.o))
 
 OBJ_TEST =
 OBJ_TEST += $(PY_O)
 OBJ_TEST += $(addprefix $(BUILD)/, $(SRC_TEST_C:.c=.o))
 OBJ_TEST += $(addprefix $(BUILD)/, $(SRC_S:.s=.o))
+OBJ_TEST += $(addprefix $(BUILD)/, $(STM_SRC_C:.c=.o))
 OBJ_TEST += $(BUILD)/tinytest.o
 
+# List of sources for qstr extraction
+SRC_QSTR += $(SRC_C) $(STM_SRC_C)
+
 all: run
 
 run: $(BUILD)/firmware.elf
diff --git a/qemu-arm/memory.h b/qemu-arm/memory.h
new file mode 100644
index 000000000..f3777b0e3
--- /dev/null
+++ b/qemu-arm/memory.h
@@ -0,0 +1,2 @@
+// this is needed for extmod/crypto-algorithms/sha256.c
+#include <string.h>
diff --git a/qemu-arm/mpconfigport.h b/qemu-arm/mpconfigport.h
index 1f23148c2..b8806405b 100644
--- a/qemu-arm/mpconfigport.h
+++ b/qemu-arm/mpconfigport.h
@@ -20,9 +20,18 @@
 #define MICROPY_PY_ARRAY_SLICE_ASSIGN (1)
 #define MICROPY_PY_BUILTINS_FROZENSET (1)
 #define MICROPY_PY_BUILTINS_MEMORYVIEW (1)
-#define MICROPY_PY_IO               (0)
+#define MICROPY_PY_IO               (1)
 #define MICROPY_PY_SYS_EXIT         (1)
 #define MICROPY_PY_SYS_MAXSIZE      (1)
+#define MICROPY_PY_UERRNO           (1)
+#define MICROPY_PY_UBINASCII        (1)
+#define MICROPY_PY_URANDOM          (1)
+#define MICROPY_PY_UCTYPES          (1)
+#define MICROPY_PY_UZLIB            (1)
+#define MICROPY_PY_UJSON            (1)
+#define MICROPY_PY_URE              (1)
+#define MICROPY_PY_UHEAPQ           (1)
+#define MICROPY_PY_UHASHLIB         (1)
 #define MICROPY_USE_INTERNAL_PRINTF (0)
 
 // type definitions for the specific machine
diff --git a/qemu-arm/mphalport.h b/qemu-arm/mphalport.h
index 4bd8276f3..d996402ae 100644
--- a/qemu-arm/mphalport.h
+++ b/qemu-arm/mphalport.h
@@ -1 +1,2 @@
-// empty file
+#define mp_hal_stdin_rx_chr() (0)
+#define mp_hal_stdout_tx_strn_cooked(s, l) write(1, (s), (l))
diff --git a/stmhal/Makefile b/stmhal/Makefile
index 7be0f28fe..e2e1dc6a1 100644
--- a/stmhal/Makefile
+++ b/stmhal/Makefile
@@ -274,16 +274,9 @@ $(PY_BUILD)/mpprint.o: COPT += -Os
 all: $(BUILD)/firmware.dfu $(BUILD)/firmware.hex
 
 ifneq ($(FROZEN_DIR),)
+# To use frozen source modules, put your .py files in a subdirectory (eg scripts/)
+# and then invoke make with FROZEN_DIR=scripts (be sure to build from scratch).
 CFLAGS += -DMICROPY_MODULE_FROZEN_STR
-OBJ += $(BUILD)/frozen-files.o
-MAKE_FROZEN = ../tools/make-frozen.py
-
-$(BUILD)/frozen-files.o: $(BUILD)/frozen-files.c
-	$(call compile_c)
-
-$(BUILD)/frozen-files.c: $(shell find $(FROZEN_DIR) -type f)
-	@$(ECHO) "Creating $@"
-	$(Q)$(PYTHON) $(MAKE_FROZEN) $(FROZEN_DIR) > $@
 endif
 
 ifneq ($(FROZEN_MPY_DIR),)
diff --git a/stmhal/accel.c b/stmhal/accel.c
index e75f1c994..827aa46e7 100644
--- a/stmhal/accel.c
+++ b/stmhal/accel.c
@@ -57,15 +57,9 @@
 #define MMA_AXIS_SIGNED_VALUE(i) (((i) & 0x3f) | ((i) & 0x20 ? (~0x1f) : 0))
 
 void accel_init(void) {
-    GPIO_InitTypeDef GPIO_InitStructure;
-
     // PB5 is connected to AVDD; pull high to enable MMA accel device
-    GPIO_clear_pin(MICROPY_HW_MMA_AVDD_PIN.gpio, MICROPY_HW_MMA_AVDD_PIN.pin_mask); // turn off AVDD
-    GPIO_InitStructure.Pin = MICROPY_HW_MMA_AVDD_PIN.pin_mask;
-    GPIO_InitStructure.Mode = GPIO_MODE_OUTPUT_PP;
-    GPIO_InitStructure.Speed = GPIO_SPEED_LOW;
-    GPIO_InitStructure.Pull = GPIO_NOPULL;
-    HAL_GPIO_Init(MICROPY_HW_MMA_AVDD_PIN.gpio, &GPIO_InitStructure);
+    mp_hal_pin_low(&MICROPY_HW_MMA_AVDD_PIN); // turn off AVDD
+    mp_hal_pin_output(&MICROPY_HW_MMA_AVDD_PIN);
 }
 
 STATIC void accel_start(void) {
@@ -81,9 +75,9 @@ STATIC void accel_start(void) {
     i2c_init(&I2CHandle1);
 
     // turn off AVDD, wait 30ms, turn on AVDD, wait 30ms again
-    GPIO_clear_pin(MICROPY_HW_MMA_AVDD_PIN.gpio, MICROPY_HW_MMA_AVDD_PIN.pin_mask); // turn off
+    mp_hal_pin_low(&MICROPY_HW_MMA_AVDD_PIN); // turn off
     HAL_Delay(30);
-    GPIO_set_pin(MICROPY_HW_MMA_AVDD_PIN.gpio, MICROPY_HW_MMA_AVDD_PIN.pin_mask); // turn on
+    mp_hal_pin_high(&MICROPY_HW_MMA_AVDD_PIN); // turn on
     HAL_Delay(30);
 
     HAL_StatusTypeDef status;
diff --git a/stmhal/boards/ESPRUINO_PICO/mpconfigboard.h b/stmhal/boards/ESPRUINO_PICO/mpconfigboard.h
index 885cedc89..d18abb908 100644
--- a/stmhal/boards/ESPRUINO_PICO/mpconfigboard.h
+++ b/stmhal/boards/ESPRUINO_PICO/mpconfigboard.h
@@ -66,6 +66,5 @@
 #define MICROPY_HW_LED2             (pin_B12) // green
 #define MICROPY_HW_LED3             (pin_B12) // green
 #define MICROPY_HW_LED4             (pin_B12) // green
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRRL = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRRH = pin->pin_mask)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
diff --git a/stmhal/boards/HYDRABUS/mpconfigboard.h b/stmhal/boards/HYDRABUS/mpconfigboard.h
index 4fe0874d7..06d169236 100644
--- a/stmhal/boards/HYDRABUS/mpconfigboard.h
+++ b/stmhal/boards/HYDRABUS/mpconfigboard.h
@@ -69,9 +69,8 @@
 #define MICROPY_HW_LED2             (pin_A4) // same as LED1
 #define MICROPY_HW_LED3             (pin_A4) // same as LED1
 #define MICROPY_HW_LED4             (pin_A4)  // same as LED1
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRRL = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRRH = pin->pin_mask)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
 
 // SD card detect switch (not used, always on)
 #define MICROPY_HW_SDCARD_DETECT_PIN        (pin_A8)
diff --git a/stmhal/boards/LIMIFROG/mpconfigboard.h b/stmhal/boards/LIMIFROG/mpconfigboard.h
index 782c9c90f..47b892233 100644
--- a/stmhal/boards/LIMIFROG/mpconfigboard.h
+++ b/stmhal/boards/LIMIFROG/mpconfigboard.h
@@ -63,9 +63,8 @@ void LIMIFROG_board_early_init(void);
 
 // LEDs
 #define MICROPY_HW_LED1             (pin_C3) // red
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRR = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRR = pin->pin_mask<<16)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
 
 // USB config
 // #define MICROPY_HW_USB_OTG_ID_PIN      (pin_C12) // This is not the official ID Pin which should be PA10
diff --git a/stmhal/boards/NETDUINO_PLUS_2/mpconfigboard.h b/stmhal/boards/NETDUINO_PLUS_2/mpconfigboard.h
index 8ec8df645..3155b6309 100644
--- a/stmhal/boards/NETDUINO_PLUS_2/mpconfigboard.h
+++ b/stmhal/boards/NETDUINO_PLUS_2/mpconfigboard.h
@@ -64,9 +64,8 @@ void NETDUINO_PLUS_2_board_early_init(void);
 #define MICROPY_HW_LED2             (pin_C13)   // White LED (aka Power)
 #define MICROPY_HW_LED3             (pin_A10)   // Same as Led(1)
 #define MICROPY_HW_LED4             (pin_C13)   // Same as Led(2)
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRRL = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRRH = pin->pin_mask)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
 
 // USB VBUS detect pin
 #define MICROPY_HW_USB_VBUS_DETECT_PIN (pin_A9)
diff --git a/stmhal/boards/NUCLEO_F401RE/mpconfigboard.h b/stmhal/boards/NUCLEO_F401RE/mpconfigboard.h
index 780eaf8fc..518f65824 100644
--- a/stmhal/boards/NUCLEO_F401RE/mpconfigboard.h
+++ b/stmhal/boards/NUCLEO_F401RE/mpconfigboard.h
@@ -54,6 +54,5 @@
 
 // LEDs
 #define MICROPY_HW_LED1             (pin_A5) // Green LD2 LED on Nucleo
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRRL = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRRH = pin->pin_mask)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
diff --git a/stmhal/boards/NUCLEO_F411RE/mpconfigboard.h b/stmhal/boards/NUCLEO_F411RE/mpconfigboard.h
index e7ffd8510..4dac80493 100644
--- a/stmhal/boards/NUCLEO_F411RE/mpconfigboard.h
+++ b/stmhal/boards/NUCLEO_F411RE/mpconfigboard.h
@@ -65,6 +65,5 @@
 
 // LEDs
 #define MICROPY_HW_LED1             (pin_A5) // Green LD2 LED on Nucleo
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRRL = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRRH = pin->pin_mask)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
diff --git a/stmhal/boards/OLIMEX_E407/mpconfigboard.h b/stmhal/boards/OLIMEX_E407/mpconfigboard.h
index c9241fe63..63ddcfb5d 100644
--- a/stmhal/boards/OLIMEX_E407/mpconfigboard.h
+++ b/stmhal/boards/OLIMEX_E407/mpconfigboard.h
@@ -71,9 +71,8 @@
 
 // LEDs
 #define MICROPY_HW_LED1             (pin_C13)
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRRH = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRRL = pin->pin_mask)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_low(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_high(pin))
 
 // SD card detect switch
 #define MICROPY_HW_SDCARD_DETECT_PIN        (pin_C11)
diff --git a/stmhal/boards/PYBLITEV10/mpconfigboard.h b/stmhal/boards/PYBLITEV10/mpconfigboard.h
index 83dcb938b..3147d2d7a 100644
--- a/stmhal/boards/PYBLITEV10/mpconfigboard.h
+++ b/stmhal/boards/PYBLITEV10/mpconfigboard.h
@@ -73,9 +73,8 @@
 #define MICROPY_HW_LED4             (pin_B4)  // blue
 #define MICROPY_HW_LED3_PWM         { TIM2, 2, TIM_CHANNEL_1, GPIO_AF1_TIM2 }
 #define MICROPY_HW_LED4_PWM         { TIM3, 3, TIM_CHANNEL_1, GPIO_AF2_TIM3 }
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRRL = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRRH = pin->pin_mask)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
 
 // SD card detect switch
 #define MICROPY_HW_SDCARD_DETECT_PIN        (pin_B5)
diff --git a/stmhal/boards/PYBV10/mpconfigboard.h b/stmhal/boards/PYBV10/mpconfigboard.h
index c654ec9a7..2540cc4eb 100644
--- a/stmhal/boards/PYBV10/mpconfigboard.h
+++ b/stmhal/boards/PYBV10/mpconfigboard.h
@@ -84,9 +84,8 @@
 #define MICROPY_HW_LED4             (pin_B4)  // blue
 #define MICROPY_HW_LED3_PWM         { TIM2, 2, TIM_CHANNEL_1, GPIO_AF1_TIM2 }
 #define MICROPY_HW_LED4_PWM         { TIM3, 3, TIM_CHANNEL_1, GPIO_AF2_TIM3 }
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRRL = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRRH = pin->pin_mask)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
 
 // SD card detect switch
 #define MICROPY_HW_SDCARD_DETECT_PIN        (pin_A8)
diff --git a/stmhal/boards/PYBV11/mpconfigboard.h b/stmhal/boards/PYBV11/mpconfigboard.h
index 9b5b7de27..881e1ccf0 100644
--- a/stmhal/boards/PYBV11/mpconfigboard.h
+++ b/stmhal/boards/PYBV11/mpconfigboard.h
@@ -84,9 +84,8 @@
 #define MICROPY_HW_LED4             (pin_B4)  // blue
 #define MICROPY_HW_LED3_PWM         { TIM2, 2, TIM_CHANNEL_1, GPIO_AF1_TIM2 }
 #define MICROPY_HW_LED4_PWM         { TIM3, 3, TIM_CHANNEL_1, GPIO_AF2_TIM3 }
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRRL = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRRH = pin->pin_mask)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
 
 // SD card detect switch
 #define MICROPY_HW_SDCARD_DETECT_PIN        (pin_A8)
diff --git a/stmhal/boards/PYBV3/mpconfigboard.h b/stmhal/boards/PYBV3/mpconfigboard.h
index 44fb22161..48d554925 100644
--- a/stmhal/boards/PYBV3/mpconfigboard.h
+++ b/stmhal/boards/PYBV3/mpconfigboard.h
@@ -73,9 +73,8 @@
 #define MICROPY_HW_LED4             (pin_C5)  // G2 - green
 #define MICROPY_HW_LED1_PWM         { TIM1, 1, TIM_CHANNEL_1, GPIO_AF1_TIM1 }
 #define MICROPY_HW_LED2_PWM         { TIM1, 1, TIM_CHANNEL_3, GPIO_AF1_TIM1 }
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRRH = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRRL = pin->pin_mask)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_low(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_high(pin))
 
 // SD card detect switch
 #define MICROPY_HW_SDCARD_DETECT_PIN        (pin_C13)
diff --git a/stmhal/boards/PYBV4/mpconfigboard.h b/stmhal/boards/PYBV4/mpconfigboard.h
index cc931fb6b..3e8300d15 100644
--- a/stmhal/boards/PYBV4/mpconfigboard.h
+++ b/stmhal/boards/PYBV4/mpconfigboard.h
@@ -81,9 +81,8 @@
 #define MICROPY_HW_LED4             (pin_B4)  // blue
 #define MICROPY_HW_LED3_PWM         { TIM2, 2, TIM_CHANNEL_1, GPIO_AF1_TIM2 }
 #define MICROPY_HW_LED4_PWM         { TIM3, 3, TIM_CHANNEL_1, GPIO_AF2_TIM3 }
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRRL = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRRH = pin->pin_mask)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
 
 // SD card detect switch
 #define MICROPY_HW_SDCARD_DETECT_PIN        (pin_A8)
diff --git a/stmhal/boards/STM32F411DISC/mpconfigboard.h b/stmhal/boards/STM32F411DISC/mpconfigboard.h
index 3bab1304c..be3589cd9 100644
--- a/stmhal/boards/STM32F411DISC/mpconfigboard.h
+++ b/stmhal/boards/STM32F411DISC/mpconfigboard.h
@@ -63,9 +63,8 @@
 #define MICROPY_HW_LED2             (pin_D12) // green
 #define MICROPY_HW_LED3             (pin_D13) // orange
 #define MICROPY_HW_LED4             (pin_D15) // blue
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRRL = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRRH = pin->pin_mask)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
 
 // USB config
 #define MICROPY_HW_USB_VBUS_DETECT_PIN (pin_A9)
diff --git a/stmhal/boards/STM32F429DISC/mpconfigboard.h b/stmhal/boards/STM32F429DISC/mpconfigboard.h
index f2cf6c142..63f22e02c 100644
--- a/stmhal/boards/STM32F429DISC/mpconfigboard.h
+++ b/stmhal/boards/STM32F429DISC/mpconfigboard.h
@@ -67,9 +67,8 @@
 // LEDs
 #define MICROPY_HW_LED1             (pin_G14) // red
 #define MICROPY_HW_LED2             (pin_G13) // green
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRRL = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRRH = pin->pin_mask)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
 
 // USB config
 #define MICROPY_HW_USB_VBUS_DETECT_PIN (pin_B13)
diff --git a/stmhal/boards/STM32F4DISC/mpconfigboard.h b/stmhal/boards/STM32F4DISC/mpconfigboard.h
index 01202e0c9..841bf7d15 100644
--- a/stmhal/boards/STM32F4DISC/mpconfigboard.h
+++ b/stmhal/boards/STM32F4DISC/mpconfigboard.h
@@ -82,9 +82,8 @@
 #define MICROPY_HW_LED2             (pin_D12) // green
 #define MICROPY_HW_LED3             (pin_D13) // orange
 #define MICROPY_HW_LED4             (pin_D15) // blue
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRRL = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRRH = pin->pin_mask)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
 
 // USB config
 #define MICROPY_HW_USB_VBUS_DETECT_PIN (pin_A9)
diff --git a/stmhal/boards/STM32F7DISC/mpconfigboard.h b/stmhal/boards/STM32F7DISC/mpconfigboard.h
index a1dbc0f46..acdc4d005 100644
--- a/stmhal/boards/STM32F7DISC/mpconfigboard.h
+++ b/stmhal/boards/STM32F7DISC/mpconfigboard.h
@@ -79,9 +79,8 @@ void STM32F7DISC_board_early_init(void);
 
 // LEDs
 #define MICROPY_HW_LED1             (pin_I1) // green
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRR = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRR = (pin->pin_mask << 16))
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
 
 // SD card detect switch
 #define MICROPY_HW_SDCARD_DETECT_PIN        (pin_C13)
diff --git a/stmhal/boards/STM32L476DISC/mpconfigboard.h b/stmhal/boards/STM32L476DISC/mpconfigboard.h
index 07e3ec7fd..55e7c9b56 100644
--- a/stmhal/boards/STM32L476DISC/mpconfigboard.h
+++ b/stmhal/boards/STM32L476DISC/mpconfigboard.h
@@ -61,9 +61,8 @@
 // LEDs
 #define MICROPY_HW_LED1             (pin_B2) // red
 #define MICROPY_HW_LED2             (pin_E8) // green
-#define MICROPY_HW_LED_OTYPE        (GPIO_MODE_OUTPUT_PP)
-#define MICROPY_HW_LED_ON(pin)      (pin->gpio->BSRR = pin->pin_mask)
-#define MICROPY_HW_LED_OFF(pin)     (pin->gpio->BSRR = pin->pin_mask<<16)
+#define MICROPY_HW_LED_ON(pin)      (mp_hal_pin_high(pin))
+#define MICROPY_HW_LED_OFF(pin)     (mp_hal_pin_low(pin))
 
 // USB config
 // #define MICROPY_HW_USB_OTG_ID_PIN      (pin_C12) // This is not the official ID Pin which should be PA10
diff --git a/stmhal/i2c.c b/stmhal/i2c.c
index 1909f8160..07269bce5 100644
--- a/stmhal/i2c.c
+++ b/stmhal/i2c.c
@@ -238,8 +238,8 @@ void i2c_init(I2C_HandleTypeDef *i2c) {
     }
 
     // init the GPIO lines
-    mp_hal_gpio_set_af(scl_pin, &GPIO_InitStructure, AF_FN_I2C, i2c_unit);
-    mp_hal_gpio_set_af(sda_pin, &GPIO_InitStructure, AF_FN_I2C, i2c_unit);
+    mp_hal_pin_set_af(scl_pin, &GPIO_InitStructure, AF_FN_I2C, i2c_unit);
+    mp_hal_pin_set_af(sda_pin, &GPIO_InitStructure, AF_FN_I2C, i2c_unit);
 
     // init the I2C device
     if (HAL_I2C_Init(i2c) != HAL_OK) {
diff --git a/stmhal/lcd.c b/stmhal/lcd.c
index 92f19b818..c406d6447 100644
--- a/stmhal/lcd.c
+++ b/stmhal/lcd.c
@@ -113,16 +113,16 @@ STATIC void lcd_delay(void) {
 
 STATIC void lcd_out(pyb_lcd_obj_t *lcd, int instr_data, uint8_t i) {
     lcd_delay();
-    GPIO_clear_pin(lcd->pin_cs1->gpio, lcd->pin_cs1->pin_mask); // CS=0; enable
+    mp_hal_pin_low(lcd->pin_cs1); // CS=0; enable
     if (instr_data == LCD_INSTR) {
-        GPIO_clear_pin(lcd->pin_a0->gpio, lcd->pin_a0->pin_mask); // A0=0; select instr reg
+        mp_hal_pin_low(lcd->pin_a0); // A0=0; select instr reg
     } else {
-        GPIO_set_pin(lcd->pin_a0->gpio, lcd->pin_a0->pin_mask); // A0=1; select data reg
+        mp_hal_pin_high(lcd->pin_a0); // A0=1; select data reg
     }
     lcd_delay();
     HAL_SPI_Transmit(lcd->spi, &i, 1, 1000);
     lcd_delay();
-    GPIO_set_pin(lcd->pin_cs1->gpio, lcd->pin_cs1->pin_mask); // CS=1; disable
+    mp_hal_pin_high(lcd->pin_cs1); // CS=1; disable
 }
 
 // write a string to the LCD at the current cursor location
@@ -262,34 +262,22 @@ STATIC mp_obj_t pyb_lcd_make_new(const mp_obj_type_t *type, mp_uint_t n_args, mp
     spi_init(lcd->spi, false);
 
     // set the pins to default values
-    GPIO_set_pin(lcd->pin_cs1->gpio, lcd->pin_cs1->pin_mask);
-    GPIO_set_pin(lcd->pin_rst->gpio, lcd->pin_rst->pin_mask);
-    GPIO_set_pin(lcd->pin_a0->gpio, lcd->pin_a0->pin_mask);
-    GPIO_clear_pin(lcd->pin_bl->gpio, lcd->pin_bl->pin_mask);
+    mp_hal_pin_high(lcd->pin_cs1);
+    mp_hal_pin_high(lcd->pin_rst);
+    mp_hal_pin_high(lcd->pin_a0);
+    mp_hal_pin_low(lcd->pin_bl);
 
     // init the pins to be push/pull outputs
-    GPIO_InitTypeDef GPIO_InitStructure;
-    GPIO_InitStructure.Mode = GPIO_MODE_OUTPUT_PP;
-    GPIO_InitStructure.Speed = GPIO_SPEED_HIGH;
-    GPIO_InitStructure.Pull = GPIO_NOPULL;
-
-    GPIO_InitStructure.Pin = lcd->pin_cs1->pin_mask;
-    HAL_GPIO_Init(lcd->pin_cs1->gpio, &GPIO_InitStructure);
-
-    GPIO_InitStructure.Pin = lcd->pin_rst->pin_mask;
-    HAL_GPIO_Init(lcd->pin_rst->gpio, &GPIO_InitStructure);
-
-    GPIO_InitStructure.Pin = lcd->pin_a0->pin_mask;
-    HAL_GPIO_Init(lcd->pin_a0->gpio, &GPIO_InitStructure);
-
-    GPIO_InitStructure.Pin = lcd->pin_bl->pin_mask;
-    HAL_GPIO_Init(lcd->pin_bl->gpio, &GPIO_InitStructure);
+    mp_hal_pin_output(lcd->pin_cs1);
+    mp_hal_pin_output(lcd->pin_rst);
+    mp_hal_pin_output(lcd->pin_a0);
+    mp_hal_pin_output(lcd->pin_bl);
 
     // init the LCD
     HAL_Delay(1); // wait a bit
-    GPIO_clear_pin(lcd->pin_rst->gpio, lcd->pin_rst->pin_mask); // RST=0; reset
+    mp_hal_pin_low(lcd->pin_rst); // RST=0; reset
     HAL_Delay(1); // wait for reset; 2us min
-    GPIO_set_pin(lcd->pin_rst->gpio, lcd->pin_rst->pin_mask); // RST=1; enable
+    mp_hal_pin_high(lcd->pin_rst); // RST=1; enable
     HAL_Delay(1); // wait for reset; 2us min
     lcd_out(lcd, LCD_INSTR, 0xa0); // ADC select, normal
     lcd_out(lcd, LCD_INSTR, 0xc0); // common output mode select, normal (this flips the display)
@@ -372,9 +360,9 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_lcd_contrast_obj, pyb_lcd_contrast);
 STATIC mp_obj_t pyb_lcd_light(mp_obj_t self_in, mp_obj_t value) {
     pyb_lcd_obj_t *self = self_in;
     if (mp_obj_is_true(value)) {
-        GPIO_set_pin(self->pin_bl->gpio, self->pin_bl->pin_mask); // set pin high to turn backlight on
+        mp_hal_pin_high(self->pin_bl); // set pin high to turn backlight on
     } else {
-        GPIO_clear_pin(self->pin_bl->gpio, self->pin_bl->pin_mask); // set pin low to turn backlight off
+        mp_hal_pin_low(self->pin_bl); // set pin low to turn backlight off
     }
     return mp_const_none;
 }
diff --git a/stmhal/led.c b/stmhal/led.c
index fdf5b04d8..310efdcda 100644
--- a/stmhal/led.c
+++ b/stmhal/led.c
@@ -67,21 +67,12 @@ STATIC const pyb_led_obj_t pyb_led_obj[] = {
 #define NUM_LEDS MP_ARRAY_SIZE(pyb_led_obj)
 
 void led_init(void) {
-    /* GPIO structure */
-    GPIO_InitTypeDef GPIO_InitStructure;
-
-    /* Configure I/O speed, mode, output type and pull */
-    GPIO_InitStructure.Speed = GPIO_SPEED_LOW;
-    GPIO_InitStructure.Mode = MICROPY_HW_LED_OTYPE;
-    GPIO_InitStructure.Pull = GPIO_NOPULL;
-
     /* Turn off LEDs and initialize */
     for (int led = 0; led < NUM_LEDS; led++) {
         const pin_obj_t *led_pin = pyb_led_obj[led].led_pin;
         mp_hal_gpio_clock_enable(led_pin->gpio);
         MICROPY_HW_LED_OFF(led_pin);
-        GPIO_InitStructure.Pin = led_pin->pin_mask;
-        HAL_GPIO_Init(led_pin->gpio, &GPIO_InitStructure);
+        mp_hal_pin_output(led_pin);
     }
 }
 
diff --git a/stmhal/modmachine.c b/stmhal/modmachine.c
index 8bd04f3ec..7a337adb6 100644
--- a/stmhal/modmachine.c
+++ b/stmhal/modmachine.c
@@ -33,6 +33,7 @@
 #include "extmod/machine_mem.h"
 #include "extmod/machine_pulse.h"
 #include "extmod/machine_i2c.h"
+#include "lib/utils/pyexec.h"
 #include "lib/fatfs/ff.h"
 #include "lib/fatfs/diskio.h"
 #include "gccollect.h"
@@ -172,6 +173,12 @@ STATIC mp_obj_t machine_reset(void) {
 }
 MP_DEFINE_CONST_FUN_OBJ_0(machine_reset_obj, machine_reset);
 
+STATIC mp_obj_t machine_soft_reset(void) {
+    pyexec_system_exit = PYEXEC_FORCED_EXIT;
+    nlr_raise(mp_obj_new_exception(&mp_type_SystemExit));
+}
+MP_DEFINE_CONST_FUN_OBJ_0(machine_soft_reset_obj, machine_soft_reset);
+
 // Activate the bootloader without BOOT* pins.
 STATIC NORETURN mp_obj_t machine_bootloader(void) {
     pyb_usb_dev_deinit();
@@ -502,6 +509,7 @@ STATIC const mp_map_elem_t machine_module_globals_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR_info),                (mp_obj_t)&machine_info_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_unique_id),           (mp_obj_t)&machine_unique_id_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_reset),               (mp_obj_t)&machine_reset_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_soft_reset),          (mp_obj_t)&machine_soft_reset_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_bootloader),          (mp_obj_t)&machine_bootloader_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_freq),                (mp_obj_t)&machine_freq_obj },
 #if MICROPY_HW_ENABLE_RNG
diff --git a/stmhal/modnwwiznet5k.c b/stmhal/modnwwiznet5k.c
index c8b5d628f..f349e40af 100644
--- a/stmhal/modnwwiznet5k.c
+++ b/stmhal/modnwwiznet5k.c
@@ -65,11 +65,11 @@ STATIC void wiz_cris_exit(void) {
 }
 
 STATIC void wiz_cs_select(void) {
-    GPIO_clear_pin(wiznet5k_obj.cs->gpio, wiznet5k_obj.cs->pin_mask);
+    mp_hal_pin_low(wiznet5k_obj.cs);
 }
 
 STATIC void wiz_cs_deselect(void) {
-    GPIO_set_pin(wiznet5k_obj.cs->gpio, wiznet5k_obj.cs->pin_mask);
+    mp_hal_pin_high(wiznet5k_obj.cs);
 }
 
 STATIC void wiz_spi_read(uint8_t *buf, uint32_t len) {
@@ -344,22 +344,12 @@ STATIC mp_obj_t wiznet5k_make_new(const mp_obj_type_t *type, mp_uint_t n_args, m
     wiznet5k_obj.spi->Init.CRCPolynomial = 7; // unused
     spi_init(wiznet5k_obj.spi, false);
 
-    GPIO_InitTypeDef GPIO_InitStructure;
-    GPIO_InitStructure.Mode = GPIO_MODE_OUTPUT_PP;
-    GPIO_InitStructure.Speed = GPIO_SPEED_FAST;
-    GPIO_InitStructure.Pull = GPIO_NOPULL;
-    GPIO_InitStructure.Pin = wiznet5k_obj.cs->pin_mask;
-    HAL_GPIO_Init(wiznet5k_obj.cs->gpio, &GPIO_InitStructure);
+    mp_hal_pin_output(wiznet5k_obj.cs);
+    mp_hal_pin_output(wiznet5k_obj.rst);
 
-    GPIO_InitStructure.Mode = GPIO_MODE_OUTPUT_PP;
-    GPIO_InitStructure.Speed = GPIO_SPEED_FAST;
-    GPIO_InitStructure.Pull = GPIO_NOPULL;
-    GPIO_InitStructure.Pin = wiznet5k_obj.rst->pin_mask;
-    HAL_GPIO_Init(wiznet5k_obj.rst->gpio, &GPIO_InitStructure);
-
-    GPIO_clear_pin(wiznet5k_obj.rst->gpio, wiznet5k_obj.rst->pin_mask);
+    mp_hal_pin_low(wiznet5k_obj.rst);
     HAL_Delay(1); // datasheet says 2us
-    GPIO_set_pin(wiznet5k_obj.rst->gpio, wiznet5k_obj.rst->pin_mask);
+    mp_hal_pin_high(wiznet5k_obj.rst);
     HAL_Delay(160); // datasheet says 150ms
 
     reg_wizchip_cris_cbfunc(wiz_cris_enter, wiz_cris_exit);
diff --git a/stmhal/modpyb.c b/stmhal/modpyb.c
index 17c3411eb..5b2bf7aa9 100644
--- a/stmhal/modpyb.c
+++ b/stmhal/modpyb.c
@@ -62,6 +62,7 @@
 #include "portmodules.h"
 #include "modmachine.h"
 #include "extmod/fsusermount.h"
+#include "extmod/utime_mphal.h"
 
 /// \function millis()
 /// Returns the number of milliseconds since the board was last reset.
@@ -162,8 +163,8 @@ STATIC const mp_map_elem_t pyb_module_globals_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR_elapsed_millis), (mp_obj_t)&pyb_elapsed_millis_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_micros), (mp_obj_t)&pyb_micros_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_elapsed_micros), (mp_obj_t)&pyb_elapsed_micros_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_delay), (mp_obj_t)&time_sleep_ms_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_udelay), (mp_obj_t)&time_sleep_us_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_delay), (mp_obj_t)&mp_utime_sleep_ms_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_udelay), (mp_obj_t)&mp_utime_sleep_us_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_sync), (mp_obj_t)&mod_os_sync_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_mount), (mp_obj_t)&fsuser_mount_obj },
 
diff --git a/stmhal/modutime.c b/stmhal/modutime.c
index 60c92d60c..fae360bb0 100644
--- a/stmhal/modutime.c
+++ b/stmhal/modutime.c
@@ -31,6 +31,7 @@
 #include "py/nlr.h"
 #include "py/smallint.h"
 #include "py/obj.h"
+#include "extmod/utime_mphal.h"
 #include "systick.h"
 #include "timeutils.h"
 #include "portmodules.h"
@@ -129,84 +130,19 @@ STATIC mp_obj_t time_time(void) {
 }
 MP_DEFINE_CONST_FUN_OBJ_0(time_time_obj, time_time);
 
-/// \function sleep(seconds)
-/// Sleep for the given number of seconds.  Seconds can be a floating-point number to
-/// sleep for a fractional number of seconds.
-STATIC mp_obj_t time_sleep(mp_obj_t seconds_o) {
-#if MICROPY_PY_BUILTINS_FLOAT
-    if (MP_OBJ_IS_INT(seconds_o)) {
-#endif
-        HAL_Delay(1000 * mp_obj_get_int(seconds_o));
-#if MICROPY_PY_BUILTINS_FLOAT
-    } else {
-        HAL_Delay((uint32_t)(1000 * mp_obj_get_float(seconds_o)));
-    }
-#endif
-    return mp_const_none;
-}
-MP_DEFINE_CONST_FUN_OBJ_1(time_sleep_obj, time_sleep);
-
-STATIC mp_obj_t time_sleep_ms(mp_obj_t ms_in) {
-    mp_int_t ms = mp_obj_get_int(ms_in);
-    if (ms > 0) {
-        HAL_Delay(ms);
-    }
-    return mp_const_none;
-}
-MP_DEFINE_CONST_FUN_OBJ_1(time_sleep_ms_obj, time_sleep_ms);
-
-STATIC mp_obj_t time_sleep_us(mp_obj_t usec_in) {
-    mp_int_t usec = mp_obj_get_int(usec_in);
-    if (usec > 0) {
-        sys_tick_udelay(usec);
-    }
-    return mp_const_none;
-}
-MP_DEFINE_CONST_FUN_OBJ_1(time_sleep_us_obj, time_sleep_us);
-
-STATIC mp_obj_t time_ticks_ms(void) {
-    return MP_OBJ_NEW_SMALL_INT(HAL_GetTick() & MP_SMALL_INT_POSITIVE_MASK);
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_ms_obj, time_ticks_ms);
-
-STATIC mp_obj_t time_ticks_us(void) {
-    return MP_OBJ_NEW_SMALL_INT(sys_tick_get_microseconds() & MP_SMALL_INT_POSITIVE_MASK);
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_us_obj, time_ticks_us);
-
-STATIC mp_obj_t time_ticks_cpu(void) {
-    static bool enabled = false;
-    if (!enabled) {
-        CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
-        DWT->CYCCNT = 0;
-        DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
-        enabled = true;
-    }
-    return MP_OBJ_NEW_SMALL_INT(DWT->CYCCNT & MP_SMALL_INT_POSITIVE_MASK);
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_0(time_ticks_cpu_obj, time_ticks_cpu);
-
-STATIC mp_obj_t time_ticks_diff(mp_obj_t start_in, mp_obj_t end_in) {
-    // we assume that the arguments come from ticks_xx so are small ints
-    uint32_t start = MP_OBJ_SMALL_INT_VALUE(start_in);
-    uint32_t end = MP_OBJ_SMALL_INT_VALUE(end_in);
-    return MP_OBJ_NEW_SMALL_INT((end - start) & MP_SMALL_INT_POSITIVE_MASK);
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_2(time_ticks_diff_obj, time_ticks_diff);
-
 STATIC const mp_map_elem_t time_module_globals_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR_utime) },
 
     { MP_OBJ_NEW_QSTR(MP_QSTR_localtime), (mp_obj_t)&time_localtime_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_mktime), (mp_obj_t)&time_mktime_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_time), (mp_obj_t)&time_time_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_sleep), (mp_obj_t)&time_sleep_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_sleep_ms), (mp_obj_t)&time_sleep_ms_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_sleep_us), (mp_obj_t)&time_sleep_us_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_ms), (mp_obj_t)&time_ticks_ms_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_us), (mp_obj_t)&time_ticks_us_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_cpu), (mp_obj_t)&time_ticks_cpu_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_diff), (mp_obj_t)&time_ticks_diff_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_sleep), (mp_obj_t)&mp_utime_sleep_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_sleep_ms), (mp_obj_t)&mp_utime_sleep_ms_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_sleep_us), (mp_obj_t)&mp_utime_sleep_us_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_ms), (mp_obj_t)&mp_utime_ticks_ms_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_us), (mp_obj_t)&mp_utime_ticks_us_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_cpu), (mp_obj_t)&mp_utime_ticks_cpu_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_ticks_diff), (mp_obj_t)&mp_utime_ticks_diff_obj },
 };
 
 STATIC MP_DEFINE_CONST_DICT(time_module_globals, time_module_globals_table);
diff --git a/stmhal/mpconfigport.h b/stmhal/mpconfigport.h
index 52fbcad68..264db3029 100644
--- a/stmhal/mpconfigport.h
+++ b/stmhal/mpconfigport.h
@@ -67,10 +67,13 @@
 #define MICROPY_USE_INTERNAL_ERRNO  (1)
 #define MICROPY_PY_FUNCTION_ATTRS   (1)
 #define MICROPY_PY_BUILTINS_STR_UNICODE (1)
+#define MICROPY_PY_BUILTINS_STR_CENTER (1)
+#define MICROPY_PY_BUILTINS_STR_PARTITION (1)
 #define MICROPY_PY_BUILTINS_STR_SPLITLINES (1)
 #define MICROPY_PY_BUILTINS_MEMORYVIEW (1)
 #define MICROPY_PY_BUILTINS_FROZENSET (1)
 #define MICROPY_PY_BUILTINS_EXECFILE (1)
+#define MICROPY_PY_BUILTINS_COMPILE (1)
 #define MICROPY_PY_ALL_SPECIAL_METHODS (1)
 #define MICROPY_PY_MICROPYTHON_MEM_INFO (1)
 #define MICROPY_PY_ARRAY_SLICE_ASSIGN (1)
@@ -94,6 +97,7 @@
 #define MICROPY_PY_URE              (1)
 #define MICROPY_PY_UHEAPQ           (1)
 #define MICROPY_PY_UHASHLIB         (1)
+#define MICROPY_PY_UTIME_MP_HAL     (1)
 #define MICROPY_PY_MACHINE          (1)
 #define MICROPY_PY_MACHINE_PULSE    (1)
 #define MICROPY_PY_MACHINE_I2C      (1)
@@ -176,6 +180,7 @@ extern const struct _mp_obj_module_t mp_module_network;
 // extra constants
 #define MICROPY_PORT_CONSTANTS \
     { MP_OBJ_NEW_QSTR(MP_QSTR_umachine), (mp_obj_t)&machine_module }, \
+    { MP_OBJ_NEW_QSTR(MP_QSTR_machine), (mp_obj_t)&machine_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_pyb), (mp_obj_t)&pyb_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_stm), (mp_obj_t)&stm_module }, \
 
diff --git a/stmhal/mphalport.c b/stmhal/mphalport.c
index f392550b8..8d6aa1a75 100644
--- a/stmhal/mphalport.c
+++ b/stmhal/mphalport.c
@@ -7,6 +7,8 @@
 #include "usb.h"
 #include "uart.h"
 
+bool mp_hal_ticks_cpu_enabled = false;
+
 // this table converts from HAL_StatusTypeDef to POSIX errno
 const byte mp_hal_status_to_errno_table[4] = {
     [HAL_OK] = 0,
@@ -71,6 +73,15 @@ void mp_hal_stdout_tx_strn_cooked(const char *str, size_t len) {
     }
 }
 
+void mp_hal_ticks_cpu_enable(void) {
+    if (!mp_hal_ticks_cpu_enabled) {
+        CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
+        DWT->CYCCNT = 0;
+        DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
+        mp_hal_ticks_cpu_enabled = true;
+    }
+}
+
 void mp_hal_gpio_clock_enable(GPIO_TypeDef *gpio) {
     if (0) {
     #ifdef __GPIOA_CLK_ENABLE
@@ -120,7 +131,9 @@ void mp_hal_gpio_clock_enable(GPIO_TypeDef *gpio) {
     }
 }
 
-void mp_hal_gpio_config(GPIO_TypeDef *gpio, uint32_t pin, uint32_t mode, uint32_t pull, uint32_t alt) {
+void mp_hal_pin_config(mp_hal_pin_obj_t pin_obj, uint32_t mode, uint32_t pull, uint32_t alt) {
+    GPIO_TypeDef *gpio = pin_obj->gpio;
+    uint32_t pin = pin_obj->pin;
     mp_hal_gpio_clock_enable(gpio);
     gpio->MODER = (gpio->MODER & ~(3 << (2 * pin))) | ((mode & 3) << (2 * pin));
     gpio->OTYPER = (gpio->OTYPER & ~(1 << pin)) | ((mode >> 2) << pin);
@@ -129,7 +142,7 @@ void mp_hal_gpio_config(GPIO_TypeDef *gpio, uint32_t pin, uint32_t mode, uint32_
     gpio->AFR[pin >> 3] = (gpio->AFR[pin >> 3] & ~(15 << (4 * (pin & 7)))) | (alt << (4 * (pin & 7)));
 }
 
-bool mp_hal_gpio_set_af(const pin_obj_t *pin, GPIO_InitTypeDef *init, uint8_t fn, uint8_t unit) {
+bool mp_hal_pin_set_af(mp_hal_pin_obj_t pin, GPIO_InitTypeDef *init, uint8_t fn, uint8_t unit) {
     mp_hal_gpio_clock_enable(pin->gpio);
 
     const pin_af_obj_t *af = pin_find_af(pin, fn, unit);
diff --git a/stmhal/mphalport.h b/stmhal/mphalport.h
index 29a9fd6c3..e58bb33b5 100644
--- a/stmhal/mphalport.h
+++ b/stmhal/mphalport.h
@@ -14,41 +14,51 @@
 #error mphalport.h: Unrecognized MCU_SERIES
 #endif
 
-// Basic GPIO functions
-#define GPIO_read_pin(gpio, pin)        (((gpio)->IDR >> (pin)) & 1)
-#if defined(MCU_SERIES_F7) || defined(MCU_SERIES_L4)
-#define GPIO_set_pin(gpio, pin_mask)    (((gpio)->BSRR) = (pin_mask))
-#define GPIO_clear_pin(gpio, pin_mask)  (((gpio)->BSRR) = ((pin_mask) << 16))
-#else
-#define GPIO_set_pin(gpio, pin_mask)    (((gpio)->BSRRL) = (pin_mask))
-#define GPIO_clear_pin(gpio, pin_mask)  (((gpio)->BSRRH) = (pin_mask))
-#endif
-#define GPIO_read_output_pin(gpio, pin) (((gpio)->ODR >> (pin)) & 1)
-
-void mp_hal_gpio_clock_enable(GPIO_TypeDef *gpio);
-void mp_hal_gpio_config(GPIO_TypeDef *gpio, uint32_t pin, uint32_t mode, uint32_t pull, uint32_t alt);
-bool mp_hal_gpio_set_af(const pin_obj_t *pin, GPIO_InitTypeDef *init, uint8_t fn, uint8_t unit);
-
 extern const unsigned char mp_hal_status_to_errno_table[4];
 
 NORETURN void mp_hal_raise(HAL_StatusTypeDef status);
 void mp_hal_set_interrupt_char(int c); // -1 to disable
 
 // timing functions
+
 #include "stmhal/systick.h"
+
 #define mp_hal_delay_ms HAL_Delay
+#define mp_hal_delay_us(us) sys_tick_udelay(us)
 #define mp_hal_delay_us_fast(us) sys_tick_udelay(us)
 #define mp_hal_ticks_ms HAL_GetTick
 #define mp_hal_ticks_us() sys_tick_get_microseconds()
 
+extern bool mp_hal_ticks_cpu_enabled;
+void mp_hal_ticks_cpu_enable(void);
+static inline mp_uint_t mp_hal_ticks_cpu(void) {
+    if (!mp_hal_ticks_cpu_enabled) {
+        mp_hal_ticks_cpu_enable();
+    }
+    return DWT->CYCCNT;
+}
+
 // C-level pin HAL
+
 #include "stmhal/pin.h"
+
 #define mp_hal_pin_obj_t const pin_obj_t*
-#define mp_hal_get_pin_obj(o) pin_find(o)
-#define mp_hal_pin_input(p) mp_hal_gpio_config((p)->gpio, (p)->pin, 0, 0, 0)
-#define mp_hal_pin_output(p) mp_hal_gpio_config((p)->gpio, (p)->pin, 1, 0, 0)
-#define mp_hal_pin_open_drain(p) mp_hal_gpio_config((p)->gpio, (p)->pin, 5, 0, 0)
-#define mp_hal_pin_od_low(p) GPIO_clear_pin((p)->gpio, (p)->pin_mask)
-#define mp_hal_pin_od_high(p) GPIO_set_pin((p)->gpio, (p)->pin_mask)
-#define mp_hal_pin_read(p) GPIO_read_pin((p)->gpio, (p)->pin)
-#define mp_hal_pin_write(p, v) do { if (v) { GPIO_set_pin((p)->gpio, (p)->pin_mask); } else { GPIO_clear_pin((p)->gpio, (p)->pin_mask); } } while (0)
+#define mp_hal_get_pin_obj(o)   pin_find(o)
+#define mp_hal_pin_input(p)     mp_hal_pin_config((p), 0, 0, 0)
+#define mp_hal_pin_output(p)    mp_hal_pin_config((p), 1, 0, 0)
+#define mp_hal_pin_open_drain(p) mp_hal_pin_config((p), 5, 0, 0)
+#if defined(MCU_SERIES_F7) || defined(MCU_SERIES_L4)
+#define mp_hal_pin_high(p)      (((p)->gpio->BSRR) = (p)->pin_mask)
+#define mp_hal_pin_low(p)       (((p)->gpio->BSRR) = ((p)->pin_mask << 16))
+#else
+#define mp_hal_pin_high(p)      (((p)->gpio->BSRRL) = (p)->pin_mask)
+#define mp_hal_pin_low(p)       (((p)->gpio->BSRRH) = (p)->pin_mask)
+#endif
+#define mp_hal_pin_od_low(p)    mp_hal_pin_low(p)
+#define mp_hal_pin_od_high(p)   mp_hal_pin_high(p)
+#define mp_hal_pin_read(p)      (((p)->gpio->IDR >> (p)->pin) & 1)
+#define mp_hal_pin_write(p, v)  do { if (v) { mp_hal_pin_high(p); } else { mp_hal_pin_low(p); } } while (0)
+
+void mp_hal_gpio_clock_enable(GPIO_TypeDef *gpio);
+void mp_hal_pin_config(mp_hal_pin_obj_t pin, uint32_t mode, uint32_t pull, uint32_t alt);
+bool mp_hal_pin_set_af(mp_hal_pin_obj_t pin, GPIO_InitTypeDef *init, uint8_t fn, uint8_t unit);
diff --git a/stmhal/pin.c b/stmhal/pin.c
index 9bd4e7a6d..21012d186 100644
--- a/stmhal/pin.c
+++ b/stmhal/pin.c
@@ -266,14 +266,10 @@ STATIC mp_obj_t pin_call(mp_obj_t self_in, mp_uint_t n_args, mp_uint_t n_kw, con
     pin_obj_t *self = self_in;
     if (n_args == 0) {
         // get pin
-        return MP_OBJ_NEW_SMALL_INT(GPIO_read_pin(self->gpio, self->pin));
+        return MP_OBJ_NEW_SMALL_INT(mp_hal_pin_read(self));
     } else {
         // set pin
-        if (mp_obj_is_true(args[0])) {
-            GPIO_set_pin(self->gpio, self->pin_mask);
-        } else {
-            GPIO_clear_pin(self->gpio, self->pin_mask);
-        }
+        mp_hal_pin_write(self, mp_obj_is_true(args[0]));
         return mp_const_none;
     }
 }
@@ -371,11 +367,7 @@ STATIC mp_obj_t pin_obj_init_helper(const pin_obj_t *self, mp_uint_t n_args, con
 
     // if given, set the pin value before initialising to prevent glitches
     if (args[3].u_obj != MP_OBJ_NULL) {
-        if (mp_obj_is_true(args[3].u_obj)) {
-            GPIO_set_pin(self->gpio, self->pin_mask);
-        } else {
-            GPIO_clear_pin(self->gpio, self->pin_mask);
-        }
+        mp_hal_pin_write(self, mp_obj_is_true(args[3].u_obj));
     }
 
     // configure the GPIO as requested
@@ -411,7 +403,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pin_value_obj, 1, 2, pin_value);
 /// Set the pin to a low logic level.
 STATIC mp_obj_t pin_low(mp_obj_t self_in) {
     pin_obj_t *self = self_in;
-    GPIO_clear_pin(self->gpio, self->pin_mask);;
+    mp_hal_pin_low(self);
     return mp_const_none;
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(pin_low_obj, pin_low);
@@ -420,7 +412,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(pin_low_obj, pin_low);
 /// Set the pin to a high logic level.
 STATIC mp_obj_t pin_high(mp_obj_t self_in) {
     pin_obj_t *self = self_in;
-    GPIO_set_pin(self->gpio, self->pin_mask);;
+    mp_hal_pin_high(self);
     return mp_const_none;
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(pin_high_obj, pin_high);
diff --git a/stmhal/pybstdio.c b/stmhal/pybstdio.c
index cf31f53ac..9cc787ce2 100644
--- a/stmhal/pybstdio.c
+++ b/stmhal/pybstdio.c
@@ -85,7 +85,7 @@ STATIC mp_uint_t stdio_write(mp_obj_t self_in, const void *buf, mp_uint_t size,
     }
 }
 
-STATIC mp_obj_t stdio_obj___exit__(mp_uint_t n_args, const mp_obj_t *args) {
+STATIC mp_obj_t stdio_obj___exit__(size_t n_args, const mp_obj_t *args) {
     return mp_const_none;
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(stdio_obj___exit___obj, 4, 4, stdio_obj___exit__);
diff --git a/stmhal/spi.c b/stmhal/spi.c
index 7f805709d..e72810d28 100644
--- a/stmhal/spi.c
+++ b/stmhal/spi.c
@@ -332,7 +332,7 @@ void spi_init(SPI_HandleTypeDef *spi, bool enable_nss_pin) {
     }
 
     for (uint i = (enable_nss_pin && pins[0] ? 0 : 1); i < 4; i++) {
-        mp_hal_gpio_set_af(pins[i], &GPIO_InitStructure, AF_FN_SPI, (self - &pyb_spi_obj[0]) + 1);
+        mp_hal_pin_set_af(pins[i], &GPIO_InitStructure, AF_FN_SPI, (self - &pyb_spi_obj[0]) + 1);
     }
 
     // init the SPI device
diff --git a/teensy/main.c b/teensy/main.c
index 890ee8149..ba7207fe8 100644
--- a/teensy/main.c
+++ b/teensy/main.c
@@ -317,7 +317,7 @@ soft_reset:
     pyexec_frozen_module("main.py");
 #else
     {
-        vstr_t *vstr = vstr_new();
+        vstr_t *vstr = vstr_new(16);
         vstr_add_str(vstr, "/");
         if (pyb_config_main == MP_OBJ_NULL) {
             vstr_add_str(vstr, "main.py");
diff --git a/teensy/teensy_hal.h b/teensy/teensy_hal.h
index b00b6e4ac..80f320e0c 100644
--- a/teensy/teensy_hal.h
+++ b/teensy/teensy_hal.h
@@ -118,7 +118,9 @@ void mp_hal_gpio_clock_enable(GPIO_TypeDef *gpio);
 
 void HAL_GPIO_Init(GPIO_TypeDef *GPIOx, GPIO_InitTypeDef *init);
 
-#define GPIO_read_pin(gpio, pin)        (((gpio)->PDIR >> (pin)) & 1)
-#define GPIO_set_pin(gpio, pin_mask)    (((gpio)->PSOR) = (pin_mask))
-#define GPIO_clear_pin(gpio, pin_mask)  (((gpio)->PCOR) = (pin_mask))
-#define GPIO_read_output_pin(gpio, pin) (((gpio)->PDOR >> (pin)) & 1)
+struct _pin_obj_t;
+#define mp_hal_pin_obj_t const struct _pin_obj_t*
+#define mp_hal_pin_high(p) (((p)->gpio->PSOR) = (p)->pin_mask)
+#define mp_hal_pin_low(p)  (((p)->gpio->PCOR) = (p)->pin_mask)
+#define mp_hal_pin_read(p) (((p)->gpio->PDIR >> (p)->pin) & 1)
+#define mp_hal_pin_write(p, v)  do { if (v) { mp_hal_pin_high(p); } else { mp_hal_pin_low(p); } } while (0)
diff --git a/tests/basics/array1.py b/tests/basics/array1.py
index e5ea6683c..c45b883c9 100644
--- a/tests/basics/array1.py
+++ b/tests/basics/array1.py
@@ -21,6 +21,10 @@ print(array.array('i'))
 print(bool(array.array('i')))
 print(bool(array.array('i', [1])))
 
+# containment, with incorrect type
+print('12' in array.array('B', b'12'))
+print([] in array.array('B', b'12'))
+
 # bad typecode
 try:
     array.array('X')
diff --git a/tests/basics/async_def.py b/tests/basics/async_def.py
new file mode 100644
index 000000000..e345703d7
--- /dev/null
+++ b/tests/basics/async_def.py
@@ -0,0 +1,16 @@
+# test async def
+
+def dec(f):
+    print('decorator')
+    return f
+
+# test definition with a decorator
+@dec
+async def foo():
+    print('foo')
+
+coro = foo()
+try:
+    coro.send(None)
+except StopIteration:
+    print('StopIteration')
diff --git a/tests/basics/async_def.py.exp b/tests/basics/async_def.py.exp
new file mode 100644
index 000000000..f555ace99
--- /dev/null
+++ b/tests/basics/async_def.py.exp
@@ -0,0 +1,3 @@
+decorator
+foo
+StopIteration
diff --git a/tests/basics/async_with.py b/tests/basics/async_with.py
index 9eccfd816..5af0c5d95 100644
--- a/tests/basics/async_with.py
+++ b/tests/basics/async_with.py
@@ -3,6 +3,7 @@
 class AContext:
     async def __aenter__(self):
         print('enter')
+        return 1
     async def __aexit__(self, exc_type, exc, tb):
         print('exit', exc_type, exc)
 
@@ -17,7 +18,8 @@ except StopIteration:
     print('finished')
 
 async def g():
-    async with AContext():
+    async with AContext() as ac:
+        print(ac)
         raise ValueError('error')
 
 o = g()
diff --git a/tests/basics/async_with.py.exp b/tests/basics/async_with.py.exp
index 6072a3e0b..d00b18c96 100644
--- a/tests/basics/async_with.py.exp
+++ b/tests/basics/async_with.py.exp
@@ -3,5 +3,6 @@ body
 exit None None
 finished
 enter
+1
 exit <class 'ValueError'> error
 ValueError
diff --git a/tests/basics/builtin_range.py b/tests/basics/builtin_range.py
index 9110cf12c..59fc0344a 100644
--- a/tests/basics/builtin_range.py
+++ b/tests/basics/builtin_range.py
@@ -50,3 +50,9 @@ try:
     range(1)[0] = 1
 except TypeError:
     print("TypeError")
+
+# bad attr (can't store)
+try:
+    range(4).start = 0
+except AttributeError:
+    print('AttributeError')
diff --git a/tests/basics/del_global.py b/tests/basics/del_global.py
index 77d11cb3c..d740357b0 100644
--- a/tests/basics/del_global.py
+++ b/tests/basics/del_global.py
@@ -54,3 +54,8 @@ try:
     print(c)
 except NameError:
     print("NameError")
+
+a = 1
+b = 2
+c = 3
+del (a, (b, c))
diff --git a/tests/basics/dict1.py b/tests/basics/dict1.py
index c70ca588a..20fa9def3 100644
--- a/tests/basics/dict1.py
+++ b/tests/basics/dict1.py
@@ -16,3 +16,27 @@ while x < 100:
     d[x] = x
     x += 1
 print(d[50])
+
+# equality operator on dicts of different size
+print({} == {1:1})
+
+# equality operator on dicts of same size but with different keys
+print({1:1} == {2:1})
+
+# value not found
+try:
+    {}[0]
+except KeyError as er:
+    print('KeyError', er, repr(er), er.args)
+
+# unsupported unary op
+try:
+    +{}
+except TypeError:
+    print('TypeError')
+
+# unsupported binary op
+try:
+    {} + {}
+except TypeError:
+    print('TypeError')
diff --git a/tests/basics/dict_views.py b/tests/basics/dict_views.py
index fbf63fa0a..7ebcc1f56 100644
--- a/tests/basics/dict_views.py
+++ b/tests/basics/dict_views.py
@@ -3,4 +3,19 @@ for m in d.items, d.values, d.keys:
     print(m())
     print(list(m()))
 
+# print a view with more than one item
+print({1:1, 2:1}.values())
+
+# unsupported binary op on a dict values view
+try:
+    {1:1}.values() + 1
+except TypeError:
+    print('TypeError')
+
+# unsupported binary op on a dict keys view
+try:
+    {1:1}.keys() + 1
+except TypeError:
+    print('TypeError')
+
 # set operations still to come
diff --git a/tests/basics/for_range.py b/tests/basics/for_range.py
index ddff5ebd4..58a8f7caa 100644
--- a/tests/basics/for_range.py
+++ b/tests/basics/for_range.py
@@ -35,6 +35,11 @@ try:
 except TypeError:
     print('TypeError')
 try:
+    for x in range(start=0, end=1):
+        print(x)
+except TypeError:
+    print('TypeError')
+try:
     for x in range(0, 1, step=1):
         print(x)
 except TypeError:
diff --git a/tests/basics/int_constfolding.py b/tests/basics/int_constfolding.py
index c01f964da..aa38fa6b8 100644
--- a/tests/basics/int_constfolding.py
+++ b/tests/basics/int_constfolding.py
@@ -38,3 +38,8 @@ print(-123 // 7, -123 % 7)
 print(123 // -7, 123 % -7)
 print(-123 // -7, -123 % -7)
 
+# zero big-num on rhs
+print(1 + ((1 << 65) - (1 << 65)))
+
+# negative big-num on rhs
+print(1 + (-(1 << 65)))
diff --git a/tests/basics/slice_attrs.py b/tests/basics/slice_attrs.py
index 76368a78c..67456ff8e 100644
--- a/tests/basics/slice_attrs.py
+++ b/tests/basics/slice_attrs.py
@@ -14,3 +14,12 @@ except:
 
 
 A()[1:2:3]
+
+# test storing to attr (shouldn't be allowed)
+class B:
+    def __getitem__(self, idx):
+        try:
+            idx.start = 0
+        except AttributeError:
+            print('AttributeError')
+B()[:]
diff --git a/tests/basics/syntaxerror.py b/tests/basics/syntaxerror.py
index 2ae0183f8..e5cbbac06 100644
--- a/tests/basics/syntaxerror.py
+++ b/tests/basics/syntaxerror.py
@@ -49,6 +49,9 @@ test_syntax("f[0]**2 = 1")
 # can't assign to empty tuple
 test_syntax("() = 1")
 
+# can't have *x on RHS
+test_syntax("x = *x")
+
 # can't have multiple *x on LHS
 test_syntax("*a, *b = c")
 
@@ -76,6 +79,7 @@ test_syntax("continue")
 test_syntax("return")
 test_syntax("yield")
 test_syntax("nonlocal a")
+test_syntax("await 1")
 
 # error on uPy, warning on CPy
 #test_syntax("def f():\n a = 1\n global a")
diff --git a/tests/basics/unpack1.py b/tests/basics/unpack1.py
index 10e01dea0..0e8ec592c 100644
--- a/tests/basics/unpack1.py
+++ b/tests/basics/unpack1.py
@@ -12,6 +12,7 @@ a, b, c = range(3); print(a, b, c)
 (a,) = range(1); print(a)
 (a, b) = range(2); print(a, b)
 (a, b, c) = range(3); print(a, b, c)
+(a, (b, c)) = [-1, range(2)]; print(a, b, c)
 
 # lists
 
diff --git a/tests/cmdline/cmd_showbc.py b/tests/cmdline/cmd_showbc.py
index 9989a7229..2f4e953bb 100644
--- a/tests/cmdline/cmd_showbc.py
+++ b/tests/cmdline/cmd_showbc.py
@@ -34,12 +34,14 @@ def f():
     # subscript
     p = b[0]
     b[0] = p
+    b[0] += p
 
     # slice
     a = b[::]
 
     # sequenc unpacking
     a, b = c
+    a, *a = a
 
     # tuple swapping
     a, b = b, a
@@ -79,6 +81,7 @@ def f():
         b
     while not a:
         b
+    a = a or a
 
     # for loop
     for a in b:
@@ -92,6 +95,11 @@ def f():
         b
     finally:
         c
+    while a:
+        try:
+            break
+        except:
+            pass
 
     # with
     with a:
@@ -117,6 +125,12 @@ def f():
     return
     return 1
 
+# function with lots of locals
+def f():
+    l1 = l2 = l3 = l4 = l5 = l6 = l7 = l8 = l9 = l10 = 1
+    m1 = m2 = m3 = m4 = m5 = m6 = m7 = m8 = m9 = m10 = 2
+    l10 + m10
+
 # functions with default args
 def f(a=1):
     pass
@@ -133,3 +147,6 @@ def f():
 # class
 class Class:
     pass
+
+# delete name
+del Class
diff --git a/tests/cmdline/cmd_showbc.py.exp b/tests/cmdline/cmd_showbc.py.exp
index 0e5c55942..1f0c054cf 100644
--- a/tests/cmdline/cmd_showbc.py.exp
+++ b/tests/cmdline/cmd_showbc.py.exp
@@ -7,9 +7,11 @@ arg names:
 (N_EXC_STACK 0)
   bc=-1 line=1
 ########
-  bc=\\d\+ line=134
+  bc=\\d\+ line=152
 00 MAKE_FUNCTION \.\+
 \\d\+ STORE_NAME f
+\\d\+ MAKE_FUNCTION \.\+
+\\d\+ STORE_NAME f
 \\d\+ LOAD_CONST_SMALL_INT 1
 \\d\+ BUILD_TUPLE 1
 \\d\+ LOAD_NULL
@@ -22,6 +24,7 @@ arg names:
 \\d\+ LOAD_CONST_STRING 'Class'
 \\d\+ CALL_FUNCTION n=2 nkw=0
 \\d\+ STORE_NAME Class
+\\d\+ DELETE_NAME Class
 \\d\+ LOAD_CONST_NONE
 \\d\+ RETURN_VALUE
 File cmdline/cmd_showbc.py, code block 'f' (descriptor: \.\+, bytecode @\.\+ bytes)
@@ -35,7 +38,7 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 (INIT_CELL 16)
   bc=-4 line=1
 ########
-  bc=\\d\+ line=118
+  bc=\\d\+ line=126
 00 LOAD_CONST_NONE
 01 LOAD_CONST_FALSE
 02 BINARY_OP 5 __add__
@@ -123,6 +126,14 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 \\d\+ LOAD_CONST_SMALL_INT 0
 \\d\+ STORE_SUBSCR
 \\d\+ LOAD_DEREF 14
+\\d\+ LOAD_CONST_SMALL_INT 0
+\\d\+ DUP_TOP_TWO
+\\d\+ LOAD_SUBSCR
+\\d\+ LOAD_FAST 12
+\\d\+ BINARY_OP 18 __iadd__
+\\d\+ ROT_THREE
+\\d\+ STORE_SUBSCR
+\\d\+ LOAD_DEREF 14
 \\d\+ LOAD_CONST_NONE
 \\d\+ LOAD_CONST_NONE
 \\d\+ BUILD_SLICE 2
@@ -132,6 +143,10 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 \\d\+ UNPACK_SEQUENCE 2
 \\d\+ STORE_FAST 0
 \\d\+ STORE_DEREF 14
+\\d\+ LOAD_FAST 0
+\\d\+ UNPACK_EX 1
+\\d\+ STORE_FAST 0
+\\d\+ STORE_FAST 0
 \\d\+ LOAD_DEREF 14
 \\d\+ LOAD_FAST 0
 \\d\+ ROT_TWO
@@ -225,6 +240,10 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 \\d\+ POP_TOP
 \\d\+ LOAD_FAST 0
 \\d\+ POP_JUMP_IF_FALSE \\d\+
+\\d\+ LOAD_FAST 0
+\\d\+ JUMP_IF_TRUE_OR_POP \\d\+
+\\d\+ LOAD_FAST 0
+\\d\+ STORE_FAST 0
 \\d\+ LOAD_DEREF 14
 \\d\+ GET_ITER
 \\d\+ FOR_ITER \\d\+
@@ -251,6 +270,17 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 \\d\+ LOAD_FAST 1
 \\d\+ POP_TOP
 \\d\+ END_FINALLY
+\\d\+ JUMP \\d\+
+\\d\+ SETUP_EXCEPT \\d\+
+\\d\+ UNWIND_JUMP \\d\+ 1
+\\d\+ POP_BLOCK
+\\d\+ JUMP \\d\+
+\\d\+ POP_TOP
+\\d\+ POP_EXCEPT
+\\d\+ JUMP \\d\+
+\\d\+ END_FINALLY
+\\d\+ LOAD_FAST 0
+\\d\+ POP_JUMP_IF_TRUE \\d\+
 \\d\+ LOAD_FAST 0
 \\d\+ SETUP_WITH \\d\+
 \\d\+ POP_TOP
@@ -291,13 +321,68 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 File cmdline/cmd_showbc.py, code block 'f' (descriptor: \.\+, bytecode @\.\+ bytes)
 Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 ########
+\.\+rg names:
+(N_STATE 22)
+(N_EXC_STACK 0)
+  bc=-1 line=1
+########
+  bc=\\d\+ line=132
+00 LOAD_CONST_SMALL_INT 1
+01 DUP_TOP
+02 STORE_FAST 0
+03 DUP_TOP
+04 STORE_FAST 1
+05 DUP_TOP
+06 STORE_FAST 2
+07 DUP_TOP
+08 STORE_FAST 3
+09 DUP_TOP
+10 STORE_FAST 4
+11 DUP_TOP
+12 STORE_FAST 5
+13 DUP_TOP
+14 STORE_FAST 6
+15 DUP_TOP
+16 STORE_FAST 7
+17 DUP_TOP
+18 STORE_FAST 8
+19 STORE_FAST 9
+20 LOAD_CONST_SMALL_INT 2
+21 DUP_TOP
+22 STORE_FAST 10
+23 DUP_TOP
+24 STORE_FAST 11
+25 DUP_TOP
+26 STORE_FAST 12
+27 DUP_TOP
+28 STORE_FAST 13
+29 DUP_TOP
+30 STORE_FAST 14
+31 DUP_TOP
+32 STORE_FAST 15
+33 DUP_TOP
+34 STORE_FAST_N 16
+36 DUP_TOP
+37 STORE_FAST_N 17
+39 DUP_TOP
+40 STORE_FAST_N 18
+42 STORE_FAST_N 19
+44 LOAD_FAST 9
+45 LOAD_FAST_N 19
+47 BINARY_OP 5 __add__
+48 POP_TOP
+49 LOAD_CONST_NONE
+50 RETURN_VALUE
+File cmdline/cmd_showbc.py, code block 'f' (descriptor: \.\+, bytecode @\.\+ bytes)
+Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
+########
 \.\+5b
 arg names: a
 (N_STATE 5)
 (N_EXC_STACK 0)
 (INIT_CELL 0)
 ########
-  bc=\\d\+ line=124
+  bc=\\d\+ line=138
 00 LOAD_CONST_SMALL_INT 2
 01 BUILD_TUPLE 1
 03 LOAD_NULL
@@ -314,9 +399,9 @@ arg names:
 (N_STATE 2)
 (N_EXC_STACK 0)
   bc=-1 line=1
-  bc=0 line=129
-  bc=3 line=130
-  bc=6 line=131
+  bc=0 line=143
+  bc=3 line=144
+  bc=6 line=145
 00 LOAD_CONST_NONE
 01 YIELD_VALUE
 02 POP_TOP
@@ -338,7 +423,7 @@ arg names:
 (N_STATE 1)
 (N_EXC_STACK 0)
   bc=-1 line=1
-  bc=13 line=135
+  bc=13 line=149
 00 LOAD_NAME __name__ (cache=0)
 04 STORE_NAME __module__
 07 LOAD_CONST_STRING 'Class'
@@ -411,7 +496,7 @@ arg names: *
 (N_EXC_STACK 0)
   bc=-\\d\+ line=1
 ########
-  bc=\\d\+ line=105
+  bc=\\d\+ line=113
 00 LOAD_DEREF 0
 02 LOAD_CONST_SMALL_INT 1
 03 BINARY_OP 5 __add__
@@ -430,7 +515,7 @@ arg names: * b
 (N_EXC_STACK 0)
   bc=-\\d\+ line=1
 ########
-  bc=\\d\+ line=125
+  bc=\\d\+ line=139
 00 LOAD_FAST 1
 01 LOAD_DEREF 0
 03 BINARY_OP 5 __add__
diff --git a/tests/cmdline/repl_basic.py b/tests/cmdline/repl_basic.py
index b416493dc..cbd5d3a4a 100644
--- a/tests/cmdline/repl_basic.py
+++ b/tests/cmdline/repl_basic.py
@@ -1,3 +1,4 @@
 # basic REPL tests
 print(1)
 
+2
diff --git a/tests/cmdline/repl_basic.py.exp b/tests/cmdline/repl_basic.py.exp
index 96b8c28dc..2b390ea98 100644
--- a/tests/cmdline/repl_basic.py.exp
+++ b/tests/cmdline/repl_basic.py.exp
@@ -5,4 +5,6 @@ Use \.\+
 1
 >>> print(1)
 1
+>>> 2
+2
 >>> 
diff --git a/tests/extmod/ujson_load.py b/tests/extmod/ujson_load.py
new file mode 100644
index 000000000..bf484a207
--- /dev/null
+++ b/tests/extmod/ujson_load.py
@@ -0,0 +1,11 @@
+try:
+    from uio import StringIO
+    import ujson as json
+except:
+    from io import StringIO
+    import json
+
+print(json.load(StringIO('null')))
+print(json.load(StringIO('"abc\\u0064e"')))
+print(json.load(StringIO('[false, true, 1, -2]')))
+print(json.load(StringIO('{"a":true}')))
diff --git a/tests/extmod/vfs_fat_ramdisk.py b/tests/extmod/vfs_fat_ramdisk.py
index f470dbcfe..6380761c6 100644
--- a/tests/extmod/vfs_fat_ramdisk.py
+++ b/tests/extmod/vfs_fat_ramdisk.py
@@ -41,8 +41,8 @@ except MemoryError:
 
 uos.VfsFat.mkfs(bdev)
 
-assert b"FOO_FILETXT" not in bdev.data
-assert b"hello!" not in bdev.data
+print(b"FOO_FILETXT" not in bdev.data)
+print(b"hello!" not in bdev.data)
 
 vfs = uos.VfsFat(bdev, "/ramdisk")
 print("statvfs:", vfs.statvfs("/ramdisk"))
@@ -57,44 +57,66 @@ f2 = vfs.open("foo_file.txt")
 print(f2.read())
 f2.close()
 
-assert b"FOO_FILETXT" in bdev.data
-assert b"hello!" in bdev.data
+print(b"FOO_FILETXT" in bdev.data)
+print(b"hello!" in bdev.data)
 
-assert vfs.listdir() == ['foo_file.txt']
+print(vfs.listdir())
+
+try:
+    vfs.rmdir("foo_file.txt")
+except OSError as e:
+    print(e.args[0] == 20) # uerrno.ENOTDIR
 
 vfs.remove('foo_file.txt')
-assert vfs.listdir() == []
+print(vfs.listdir())
 
 vfs.mkdir("foo_dir")
-assert vfs.listdir() == ['foo_dir']
+print(vfs.listdir())
+
+try:
+    vfs.remove("foo_dir")
+except OSError as e:
+    print(e.args[0] == uerrno.EISDIR)
+
 f = vfs.open("foo_dir/file-in-dir.txt", "w")
 f.write("data in file")
 f.close()
 
-assert vfs.listdir("foo_dir") == ['file-in-dir.txt']
+print(vfs.listdir("foo_dir"))
 
 vfs.rename("foo_dir/file-in-dir.txt", "moved-to-root.txt")
-assert vfs.listdir() == ['foo_dir', 'moved-to-root.txt']
+print(vfs.listdir())
 
 vfs.chdir("foo_dir")
 print("getcwd:", vfs.getcwd())
-assert vfs.listdir() == []
+print(vfs.listdir())
 
 with vfs.open("sub_file.txt", "w") as f:
     f.write("test2")
-assert vfs.listdir() == ["sub_file.txt"]
+print(vfs.listdir())
+
+try:
+    vfs.chdir("sub_file.txt")
+except OSError as e:
+    print(e.args[0] == uerrno.ENOENT)
 
 vfs.chdir("..")
 print("getcwd:", vfs.getcwd())
 
+try:
+    vfs.rmdir("foo_dir")
+except OSError as e:
+    print(e.args[0] == uerrno.EACCES)
+
+vfs.remove("foo_dir/sub_file.txt")
+vfs.rmdir("foo_dir")
+print(vfs.listdir())
 
 vfs.umount()
 try:
     vfs.listdir()
 except OSError as e:
-    assert e.args[0] == uerrno.ENODEV
-else:
-    raise AssertionError("expected OSError not thrown")
+    print(e.args[0] == uerrno.ENODEV)
 
 vfs = uos.VfsFat(bdev, "/ramdisk")
-assert  vfs.listdir() == ['foo_dir', 'moved-to-root.txt']
+print(vfs.listdir())
diff --git a/tests/extmod/vfs_fat_ramdisk.py.exp b/tests/extmod/vfs_fat_ramdisk.py.exp
index fd893b6e4..8a498b2fc 100644
--- a/tests/extmod/vfs_fat_ramdisk.py.exp
+++ b/tests/extmod/vfs_fat_ramdisk.py.exp
@@ -1,5 +1,23 @@
+True
+True
 statvfs: (512, 512, 14, 14, 14, 0, 0, 0, 0, 255)
 getcwd: /ramdisk
 hello!
+True
+True
+['foo_file.txt']
+True
+[]
+['foo_dir']
+True
+['file-in-dir.txt']
+['foo_dir', 'moved-to-root.txt']
 getcwd: /ramdisk/foo_dir
+[]
+['sub_file.txt']
+True
 getcwd: /ramdisk
+True
+['moved-to-root.txt']
+True
+['moved-to-root.txt']
diff --git a/tests/import/import2a.py b/tests/import/import2a.py
index ce32b10b1..def6aeb6a 100644
--- a/tests/import/import2a.py
+++ b/tests/import/import2a.py
@@ -1,2 +1,5 @@
 from import1b import var
 print(var)
+
+from import1b import var as var2
+print(var2)
diff --git a/tests/micropython/emg_exc.py b/tests/micropython/emg_exc.py
new file mode 100644
index 000000000..d228e6faa
--- /dev/null
+++ b/tests/micropython/emg_exc.py
@@ -0,0 +1,20 @@
+# test that emergency exceptions work
+
+import micropython
+import sys
+
+# some ports need to allocate heap for the emg exc
+try:
+    micropython.alloc_emergency_exception_buf(256)
+except AttributeError:
+    pass
+
+def f():
+    micropython.heap_lock()
+    try:
+        raise ValueError(1)
+    except ValueError as er:
+        sys.print_exception(er)
+    micropython.heap_unlock()
+
+f()
diff --git a/tests/micropython/emg_exc.py.exp b/tests/micropython/emg_exc.py.exp
new file mode 100644
index 000000000..82b10b5f5
--- /dev/null
+++ b/tests/micropython/emg_exc.py.exp
@@ -0,0 +1 @@
+ValueError: 
diff --git a/tests/micropython/heap_lock.py b/tests/micropython/heap_lock.py
new file mode 100644
index 000000000..0f0a70eff
--- /dev/null
+++ b/tests/micropython/heap_lock.py
@@ -0,0 +1,14 @@
+# check that heap_lock/heap_unlock work as expected
+
+import micropython
+
+micropython.heap_lock()
+
+try:
+    print([])
+except MemoryError:
+    print('MemoryError')
+
+micropython.heap_unlock()
+
+print([])
diff --git a/tests/micropython/heap_lock.py.exp b/tests/micropython/heap_lock.py.exp
new file mode 100644
index 000000000..67b208cfc
--- /dev/null
+++ b/tests/micropython/heap_lock.py.exp
@@ -0,0 +1,2 @@
+MemoryError
+[]
diff --git a/tests/micropython/heapalloc.py b/tests/micropython/heapalloc.py
index 2dc7fa5e7..a651158ca 100644
--- a/tests/micropython/heapalloc.py
+++ b/tests/micropython/heapalloc.py
@@ -1,6 +1,6 @@
 # check that we can do certain things without allocating heap memory
 
-import gc
+import micropython
 
 def f1(a):
     print(a)
@@ -28,12 +28,7 @@ def test():
         f2(i, i)        # 2 args
     f3(1, 2, 3, 4)  # function with lots of local state
 
-# call h with heap allocation disabled and all memory used up
-gc.disable()
-try:
-    while True:
-        'a'.lower # allocates 1 cell for boundmeth
-except MemoryError:
-    pass
+# call test() with heap allocation disabled
+micropython.heap_lock()
 test()
-gc.enable()
+micropython.heap_unlock()
diff --git a/tests/micropython/opt_level.py b/tests/micropython/opt_level.py
new file mode 100644
index 000000000..4e2f2f4ea
--- /dev/null
+++ b/tests/micropython/opt_level.py
@@ -0,0 +1,14 @@
+import micropython as micropython
+
+# check we can get and set the level
+micropython.opt_level(0)
+print(micropython.opt_level())
+micropython.opt_level(1)
+print(micropython.opt_level())
+
+# check that the optimisation levels actually differ
+micropython.opt_level(0)
+exec('print(__debug__)')
+micropython.opt_level(1)
+exec('print(__debug__)')
+exec('assert 0')
diff --git a/tests/micropython/opt_level.py.exp b/tests/micropython/opt_level.py.exp
new file mode 100644
index 000000000..74b3dd74e
--- /dev/null
+++ b/tests/micropython/opt_level.py.exp
@@ -0,0 +1,4 @@
+0
+1
+True
+False
diff --git a/tests/micropython/viper_args.py b/tests/micropython/viper_args.py
index ca2a5e670..2aebe1b04 100644
--- a/tests/micropython/viper_args.py
+++ b/tests/micropython/viper_args.py
@@ -26,3 +26,11 @@ def f4(x1:int, x2:int, x3:int, x4:int):
 f4(1, 2, 3, 4)
 
 # only up to 4 arguments currently supported
+
+# test compiling *x, **x, * args (currently unsupported at runtime)
+@micropython.viper
+def f(*x, **y):
+    pass
+@micropython.viper
+def f(*):
+    pass
diff --git a/tests/misc/non_compliant.py b/tests/misc/non_compliant.py
index 1157ff8b2..677438b83 100644
--- a/tests/misc/non_compliant.py
+++ b/tests/misc/non_compliant.py
@@ -3,6 +3,18 @@
 import array
 import ustruct
 
+# when super can't find self
+try:
+    exec('def f(): super()')
+except SyntaxError:
+    print('SyntaxError')
+
+# store to exception attribute is not allowed
+try:
+    ValueError().x = 0
+except AttributeError:
+    print('AttributeError')
+
 # array deletion not implemented
 try:
     a = array.array('b', (1, 2, 3))
@@ -17,6 +29,12 @@ try:
 except NotImplementedError:
     print('NotImplementedError')
 
+# containment, looking for integer not implemented
+try:
+    print(1 in array.array('B', b'12'))
+except NotImplementedError:
+    print('NotImplementedError')
+
 # should raise type error
 try:
     print(set('12') >= '1')
@@ -59,6 +77,12 @@ try:
 except NotImplementedError:
     print('NotImplementedError')
 
+# str subscr with step!=1 not implemented
+try:
+    print('abc'[1:2:3])
+except NotImplementedError:
+    print('NotImplementedError')
+
 # bytes(...) with keywords not implemented
 try:
     bytes('abc', encoding='utf8')
diff --git a/tests/misc/non_compliant.py.exp b/tests/misc/non_compliant.py.exp
index c03580442..737650e9e 100644
--- a/tests/misc/non_compliant.py.exp
+++ b/tests/misc/non_compliant.py.exp
@@ -1,5 +1,8 @@
+SyntaxError
+AttributeError
 TypeError
 NotImplementedError
+NotImplementedError
 True
 True
 TypeError, ValueError
@@ -12,5 +15,6 @@ NotImplementedError
 NotImplementedError
 NotImplementedError
 NotImplementedError
+NotImplementedError
 b'\x01\x02'
 b'\x01\x00'
diff --git a/tests/run-tests b/tests/run-tests
index cb920c094..4ac7d8e28 100755
--- a/tests/run-tests
+++ b/tests/run-tests
@@ -237,7 +237,6 @@ def run_tests(pyb, tests, args):
         skip_tests.add('float/float_divmod.py') # tested by float/float_divmod_relaxed.py instead
         skip_tests.add('float/float2int_doubleprec.py') # requires double precision floating point to work
         skip_tests.add('micropython/meminfo.py') # output is very different to PC output
-        skip_tests.add('extmod/machine1.py') # raw memory access not supported
         skip_tests.add('extmod/machine_mem.py') # raw memory access not supported
 
         if args.target == 'wipy':
@@ -273,7 +272,7 @@ def run_tests(pyb, tests, args):
     if args.emit == 'native':
         skip_tests.update({'basics/%s.py' % t for t in 'gen_yield_from gen_yield_from_close gen_yield_from_ducktype gen_yield_from_exc gen_yield_from_iter gen_yield_from_send gen_yield_from_stopped gen_yield_from_throw generator1 generator2 generator_args generator_close generator_closure generator_exc generator_return generator_send'.split()}) # require yield
         skip_tests.update({'basics/%s.py' % t for t in 'bytes_gen class_store_class globals_del string_join'.split()}) # require yield
-        skip_tests.update({'basics/async_%s.py' % t for t in 'await await2 for for2 with with2'.split()}) # require yield
+        skip_tests.update({'basics/async_%s.py' % t for t in 'def await await2 for for2 with with2'.split()}) # require yield
         skip_tests.update({'basics/%s.py' % t for t in 'try_reraise try_reraise2'.split()}) # require raise_varargs
         skip_tests.update({'basics/%s.py' % t for t in 'with_break with_continue with_return'.split()}) # require complete with support
         skip_tests.add('basics/array_construct2.py') # requires generators
diff --git a/tests/unicode/unicode.py b/tests/unicode/unicode.py
index b31f064e9..5f29bc1c9 100644
--- a/tests/unicode/unicode.py
+++ b/tests/unicode/unicode.py
@@ -18,8 +18,9 @@ enc = s.encode()
 print(enc, enc.decode() == s)
 
 # printing of unicode chars using repr
-# TODO we don't do this correctly
-#print(repr(s))
+# NOTE: for some characters (eg \u10ff) we differ to CPython
+print(repr('a\uffff'))
+print(repr('a\U0001ffff'))
 
 # test invalid escape code
 try:
diff --git a/tools/micropython-upip-1.0.tar.gz b/tools/micropython-upip-1.0.tar.gz
deleted file mode 100644
index f34915070..000000000
--- a/tools/micropython-upip-1.0.tar.gz
+++ /dev/null
diff --git a/tools/micropython-upip-1.1.3.tar.gz b/tools/micropython-upip-1.1.3.tar.gz
new file mode 100644
index 000000000..90f726d86
--- /dev/null
+++ b/tools/micropython-upip-1.1.3.tar.gz
diff --git a/tools/tinytest-codegen.py b/tools/tinytest-codegen.py
index 091c1b065..bab937135 100755
--- a/tools/tinytest-codegen.py
+++ b/tools/tinytest-codegen.py
@@ -46,8 +46,15 @@ testgroup_member = (
 
 ## XXX: may be we could have `--without <groups>` argument...
 # currently these tests are selected because they pass on qemu-arm
-test_dirs = ('basics', 'micropython', 'inlineasm') # 'float', 'import', 'io', 'misc')
-exclude_tests = ('inlineasm/asmfpaddsub.py', 'inlineasm/asmfpcmp.py', 'inlineasm/asmfpldrstr.py', 'inlineasm/asmfpmuldiv.py', 'inlineasm/asmfpsqrt.py',)
+test_dirs = ('basics', 'micropython', 'extmod', 'inlineasm') # 'float', 'import', 'io', 'misc')
+exclude_tests = (
+    'inlineasm/asmfpaddsub.py', 'inlineasm/asmfpcmp.py', 'inlineasm/asmfpldrstr.py', 'inlineasm/asmfpmuldiv.py', 'inlineasm/asmfpsqrt.py',
+    'extmod/time_ms_us.py',
+    'extmod/ujson_dumps_float.py', 'extmod/ujson_loads_float.py',
+    'extmod/uctypes_native_float.py', 'extmod/uctypes_le_float.py',
+    'extmod/machine_pinbase.py', 'extmod/machine_pulse.py',
+    'extmod/vfs_fat_ramdisk.py',
+)
 
 output = []
 
diff --git a/unix/Makefile b/unix/Makefile
index 4a313b3a8..53ff4cb48 100644
--- a/unix/Makefile
+++ b/unix/Makefile
@@ -273,7 +273,7 @@ coverage_test: coverage
 	gcov -o build-coverage/extmod ../extmod/*.c
 
 $(BUILD)/_frozen_upip.c: $(BUILD)/frozen_upip/upip.py
-	../tools/make-frozen.py $(dir $^) > $@
+	$(MAKE_FROZEN) $(dir $^) > $@
 
 # Select latest upip version available
 UPIP_TARBALL := $(shell ls -1 -v ../tools/micropython-upip-*.tar.gz | tail -n1)
diff --git a/unix/coverage.c b/unix/coverage.c
index c84a653f7..6a1b43fdc 100644
--- a/unix/coverage.c
+++ b/unix/coverage.c
@@ -34,7 +34,7 @@ STATIC mp_obj_t extra_coverage(void) {
     // vstr
     {
         mp_printf(&mp_plat_print, "# vstr\n");
-        vstr_t *vstr = vstr_new_size(16);
+        vstr_t *vstr = vstr_new(16);
         vstr_hint_size(vstr, 32);
         vstr_add_str(vstr, "ts");
         vstr_ins_byte(vstr, 1, 'e');
diff --git a/zephyr/Makefile b/zephyr/Makefile
index d0dce488d..9682dc5cc 100644
--- a/zephyr/Makefile
+++ b/zephyr/Makefile
@@ -15,6 +15,8 @@ BOARD ?= qemu_x86
 # Zephyr 1.6.0
 OUTDIR_PREFIX = $(BOARD)
 
+FROZEN_DIR = scripts
+
 # Zephyr (generated) config files - must be defined before include below
 Z_SYSGEN_H = outdir/$(OUTDIR_PREFIX)/misc/generated/sysgen/sysgen.h
 Z_EXPORTS = outdir/$(OUTDIR_PREFIX)/Makefile.export
@@ -31,13 +33,19 @@ INC += -I$(ZEPHYR_BASE)/net/ip/contiki
 INC += -I$(ZEPHYR_BASE)/net/ip/contiki/os
 
 SRC_C = main.c \
+	help.c \
 	uart_core.c \
 	lib/utils/stdout_helpers.c \
 	lib/utils/printf.c \
 	lib/utils/pyexec.c \
+	lib/utils/interrupt_char.c \
+	lib/utils/pyhelp.c \
 	lib/mp-readline/readline.c \
 	$(SRC_MOD)
 
+# List of sources for qstr extraction
+SRC_QSTR += $(SRC_C)
+
 OBJ = $(PY_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 
 CFLAGS = $(KBUILD_CFLAGS) $(NOSTDINC_FLAGS) $(ZEPHYRINCLUDE) \
diff --git a/zephyr/README.md b/zephyr/README.md
index 43e92c787..63fb0e39f 100644
--- a/zephyr/README.md
+++ b/zephyr/README.md
@@ -41,5 +41,5 @@ qemu_cortex_m3):
 
     make qemu
 
-For deploying/flashing teh application on a real board, follow Zephyr
+For deploying/flashing the application on a real board, follow Zephyr
 documentation for a given board.
diff --git a/zephyr/help.c b/zephyr/help.c
new file mode 100644
index 000000000..e574adf47
--- /dev/null
+++ b/zephyr/help.c
@@ -0,0 +1,56 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013-2016 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdio.h>
+
+#include "lib/utils/pyhelp.h"
+
+STATIC const char *help_text =
+"Welcome to MicroPython!\n"
+"\n"
+"Control commands:\n"
+"  CTRL-A        -- on a blank line, enter raw REPL mode\n"
+"  CTRL-B        -- on a blank line, enter normal REPL mode\n"
+"  CTRL-C        -- interrupt a running program\n"
+"  CTRL-D        -- on a blank line, do a soft reset of the board\n"
+"  CTRL-E        -- on a blank line, enter paste mode\n"
+"\n"
+"For further help on a specific object, type help(obj)\n"
+;
+
+STATIC mp_obj_t builtin_help(uint n_args, const mp_obj_t *args) {
+    if (n_args == 0) {
+        // print a general help message
+        printf("%s", help_text);
+
+    } else {
+        // try to print something sensible about the given object
+        pyhelp_print_obj(args[0]);
+    }
+
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_builtin_help_obj, 0, 1, builtin_help);
diff --git a/zephyr/main.c b/zephyr/main.c
index 65074b157..8d319098b 100644
--- a/zephyr/main.c
+++ b/zephyr/main.c
@@ -1,3 +1,29 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013, 2014 Damien P. George
+ * Copyright (c) 2016 Linaro Limited
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
@@ -7,7 +33,9 @@
 #include "py/runtime.h"
 #include "py/repl.h"
 #include "py/gc.h"
+#include "py/stackctrl.h"
 #include "lib/utils/pyexec.h"
+#include "lib/mp-readline/readline.h"
 
 void do_str(const char *src, mp_parse_input_kind_t input_kind) {
     mp_lexer_t *lex = mp_lexer_new_from_str_len(MP_QSTR__lt_stdin_gt_, src, strlen(src), 0);
@@ -35,11 +63,16 @@ static char heap[16 * 1024];
 int real_main(void) {
     int stack_dummy;
     stack_top = (char*)&stack_dummy;
+    mp_stack_set_top(stack_top);
+    // Should be set to stack size in prj.mdef minus fuzz factor
+    mp_stack_set_limit(3584);
 
     #if MICROPY_ENABLE_GC
     gc_init(heap, heap + sizeof(heap));
     #endif
     mp_init();
+    MP_STATE_PORT(mp_kbd_exception) = mp_obj_new_exception(&mp_type_KeyboardInterrupt);
+    pyexec_frozen_module("main.py");
     #if MICROPY_REPL_EVENT_DRIVEN
     pyexec_event_repl_init();
     for (;;) {
diff --git a/zephyr/mpconfigport.h b/zephyr/mpconfigport.h
index cf5884e0e..1654e79b8 100644
--- a/zephyr/mpconfigport.h
+++ b/zephyr/mpconfigport.h
@@ -1,10 +1,39 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Linaro Limited
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
 #include <alloca.h>
 
+// Include Zephyr's autoconf.h, which should be made first by Zephyr makefiles
+#include "autoconf.h"
+
 // Saving extra crumbs to make sure binary fits in 128K
 #define MICROPY_COMP_CONST_FOLDING  (0)
 #define MICROPY_COMP_CONST (0)
 #define MICROPY_COMP_DOUBLE_TUPLE_ASSIGN (0)
 
+#define MICROPY_STACK_CHECK         (1)
 #define MICROPY_ENABLE_GC           (1)
 #define MICROPY_HELPER_REPL         (1)
 #define MICROPY_REPL_AUTO_INDENT    (1)
@@ -23,6 +52,7 @@
 #define MICROPY_PY_COLLECTIONS      (0)
 #define MICROPY_PY_CMATH            (0)
 #define MICROPY_PY_IO               (0)
+#define MICROPY_PY_MICROPYTHON_MEM_INFO (1)
 #define MICROPY_PY_STRUCT           (0)
 #define MICROPY_PY_SYS_MODULES      (0)
 #define MICROPY_LONGINT_IMPL (MICROPY_LONGINT_IMPL_LONGLONG)
@@ -30,6 +60,7 @@
 #define MICROPY_PY_BUILTINS_COMPLEX (0)
 #define MICROPY_HW_BOARD_NAME "zephyr-generic"
 #define MICROPY_HW_MCU_NAME "unknown-cpu"
+#define MICROPY_MODULE_FROZEN_STR   (1)
 
 typedef int mp_int_t; // must be pointer size
 typedef unsigned mp_uint_t; // must be pointer size
@@ -43,7 +74,10 @@ typedef long mp_off_t;
 #define MP_STATE_PORT MP_STATE_VM
 
 #define MICROPY_PORT_ROOT_POINTERS \
+    mp_obj_t mp_kbd_exception; \
     const char *readline_hist[8];
 
-// Include Zephyr's autoconf.h, which should be made first by Zephyr makefiles
-#include "autoconf.h"
+// extra built in names to add to the global namespace
+#define MICROPY_PORT_BUILTINS \
+    { MP_OBJ_NEW_QSTR(MP_QSTR_help), (mp_obj_t)&mp_builtin_help_obj }, \
+
diff --git a/zephyr/mphalport.h b/zephyr/mphalport.h
index 60d68bd2d..1bb64e000 100644
--- a/zephyr/mphalport.h
+++ b/zephyr/mphalport.h
@@ -1,2 +1 @@
 static inline mp_uint_t mp_hal_ticks_ms(void) { return 0; }
-static inline void mp_hal_set_interrupt_char(char c) {}
diff --git a/zephyr/src/zephyr_getchar.c b/zephyr/src/zephyr_getchar.c
index 3a1898a60..89e3e0efb 100644
--- a/zephyr/src/zephyr_getchar.c
+++ b/zephyr/src/zephyr_getchar.c
@@ -20,6 +20,9 @@
 #include <misc/printk.h>
 #include "zephyr_getchar.h"
 
+extern int mp_interrupt_char;
+void mp_keyboard_interrupt(void);
+
 static struct nano_sem uart_sem;
 #define UART_BUFSIZE 256
 static uint8_t uart_ringbuf[UART_BUFSIZE];
@@ -32,8 +35,13 @@ static int console_irq_input_hook(struct device *dev, uint8_t ch)
         printk("UART buffer overflow - char dropped\n");
         return 1;
     }
-    uart_ringbuf[i_put] = ch;
-    i_put = i_next;
+    if (ch == mp_interrupt_char) {
+        mp_keyboard_interrupt();
+        return 1;
+    } else {
+        uart_ringbuf[i_put] = ch;
+        i_put = i_next;
+    }
     //printk("%x\n", ch);
     nano_isr_sem_give(&uart_sem);
     return 1;
diff --git a/zephyr/src/zephyr_start.c b/zephyr/src/zephyr_start.c
index b490cc770..9e8a90beb 100644
--- a/zephyr/src/zephyr_start.c
+++ b/zephyr/src/zephyr_start.c
@@ -1,3 +1,28 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Linaro Limited
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
 #include <zephyr.h>
 #include "zephyr_getchar.h"
 
diff --git a/zephyr/uart_core.c b/zephyr/uart_core.c
index 5f48f973f..702c97d20 100644
--- a/zephyr/uart_core.c
+++ b/zephyr/uart_core.c
@@ -1,3 +1,28 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Linaro Limited
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
 #include <unistd.h>
 #include "py/mpconfig.h"
 #include "src/zephyr_getchar.h"