Merge branch 'master' into nrf52840_usbboot

29 files changed, 357 insertions, 706 deletions

diff --git a/.gitignore b/.gitignore
index c728a3cf3..042d53bcd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -58,3 +58,4 @@ TAGS
 #################
 *.orig
 
+*.DS_Store
diff --git a/lib/utils/pyexec.c b/lib/utils/pyexec.c
index 718c6828c..929ee5224 100644..100755
--- a/lib/utils/pyexec.c
+++ b/lib/utils/pyexec.c
@@ -33,6 +33,7 @@
 #include "py/runtime.h"
 #include "py/repl.h"
 #include "py/gc.h"
+#include "py/gc_long_lived.h"
 #include "py/frozenmod.h"
 #include "py/mphal.h"
 #if defined(USE_DEVICE_MODE)
@@ -97,6 +98,13 @@ STATIC int parse_compile_execute(const void *source, mp_parse_input_kind_t input
             #endif
         }
 
+        // If the code was loaded from a file its likely to be running for a while so we'll long
+        // live it and collect any garbage before running.
+        if (input_kind == MP_PARSE_FILE_INPUT) {
+            module_fun = make_obj_long_lived(module_fun, 6);
+            gc_collect();
+        }
+
         // execute code
         mp_hal_set_interrupt_char(CHAR_CTRL_C); // allow ctrl-C to interrupt us
         start = mp_hal_ticks_ms();
diff --git a/main.c b/main.c
index cbc0b093c..91d820089 100644..100755
--- a/main.c
+++ b/main.c
@@ -44,6 +44,7 @@
 #include "lib/utils/pyexec.h"
 
 #include "mpconfigboard.h"
+#include "supervisor/cpu.h"
 #include "supervisor/port.h"
 #include "supervisor/filesystem.h"
 // TODO(tannewt): Figure out how to choose language at compile time.
@@ -381,16 +382,17 @@ int __attribute__((used)) main(void) {
 }
 
 void gc_collect(void) {
-    // WARNING: This gc_collect implementation doesn't try to get root
-    // pointers from CPU registers, and thus may function incorrectly.
-    void *dummy;
     gc_collect_start();
+
+    mp_uint_t regs[10];
+    mp_uint_t sp = cpu_get_regs_and_sp(regs);
+
     // This collects root pointers from the VFS mount table. Some of them may
     // have lost their references in the VM even though they are mounted.
     gc_collect_root((void**)&MP_STATE_VM(vfs_mount_table), sizeof(mp_vfs_mount_t) / sizeof(mp_uint_t));
     // This naively collects all object references from an approximate stack
     // range.
-    gc_collect_root(&dummy, ((mp_uint_t)&_estack - (mp_uint_t)&dummy) / sizeof(mp_uint_t));
+    gc_collect_root((void**)sp, ((uint32_t)&_estack - sp) / sizeof(uint32_t));
     gc_collect_end();
 }
 
diff --git a/ports/atmel-samd/Makefile b/ports/atmel-samd/Makefile
index 731e82677..9c14ac29c 100644..100755
--- a/ports/atmel-samd/Makefile
+++ b/ports/atmel-samd/Makefile
@@ -412,6 +412,8 @@ endif
 SRC_SHARED_MODULE_EXPANDED = $(addprefix shared-bindings/, $(SRC_SHARED_MODULE)) \
                              $(addprefix shared-module/, $(SRC_SHARED_MODULE))
 
+SRC_S = supervisor/$(CHIP_FAMILY)_cpu.s
+
 OBJ = $(PY_O) $(SUPERVISOR_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_ASF:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_COMMON_HAL_EXPANDED:.c=.o))
@@ -419,6 +421,7 @@ OBJ += $(addprefix $(BUILD)/, $(SRC_SHARED_MODULE_EXPANDED:.c=.o))
 ifeq ($(INTERNAL_LIBM),1)
 OBJ += $(addprefix $(BUILD)/, $(SRC_LIBM:.c=.o))
 endif
+OBJ += $(addprefix $(BUILD)/, $(SRC_S:.s=.o))
 
 SRC_QSTR += $(SRC_C) $(SRC_SUPERVISOR) $(SRC_COMMON_HAL_EXPANDED) $(SRC_SHARED_MODULE_EXPANDED) $(STM_SRC_C)
 
diff --git a/ports/atmel-samd/supervisor/samd21_cpu.s b/ports/atmel-samd/supervisor/samd21_cpu.s
new file mode 100755
index 000000000..741bb2135
--- /dev/null
+++ b/ports/atmel-samd/supervisor/samd21_cpu.s
@@ -0,0 +1,35 @@
+.syntax unified
+.cpu cortex-m0
+.thumb
+.text
+.align  2
+
+@ uint cpu_get_regs_and_sp(r0=uint regs[10])
+.global cpu_get_regs_and_sp
+.thumb
+.thumb_func
+.type   cpu_get_regs_and_sp, %function
+cpu_get_regs_and_sp:
+@ store registers into given array
+str     r4, [r0, #0]
+str     r5, [r0, #4]
+str     r6, [r0, #8]
+str     r7, [r0, #12]
+push {r1}
+mov     r1, r8
+str     r1, [r0, #16]
+mov     r1, r9
+str     r1, [r0, #20]
+mov     r1, r10
+str     r1, [r0, #24]
+mov     r1, r11
+str     r1, [r0, #28]
+mov     r1, r12
+str     r1, [r0, #32]
+mov     r1, r13
+str     r1, [r0, #36]
+pop {r1}
+
+@ return the sp
+mov     r0, sp
+bx      lr
diff --git a/ports/atmel-samd/supervisor/samd51_cpu.s b/ports/atmel-samd/supervisor/samd51_cpu.s
new file mode 100755
index 000000000..9e6807a5e
--- /dev/null
+++ b/ports/atmel-samd/supervisor/samd51_cpu.s
@@ -0,0 +1,27 @@
+.syntax unified
+.cpu cortex-m4
+.thumb
+.text
+.align  2
+
+@ uint cpu_get_regs_and_sp(r0=uint regs[10])
+.global cpu_get_regs_and_sp
+.thumb
+.thumb_func
+.type   cpu_get_regs_and_sp, %function
+cpu_get_regs_and_sp:
+@ store registers into given array
+str     r4, [r0], #4
+str     r5, [r0], #4
+str     r6, [r0], #4
+str     r7, [r0], #4
+str     r8, [r0], #4
+str     r9, [r0], #4
+str     r10, [r0], #4
+str     r11, [r0], #4
+str     r12, [r0], #4
+str     r13, [r0], #4
+
+@ return the sp
+mov     r0, sp
+bx      lr
diff --git a/ports/nrf/Makefile b/ports/nrf/Makefile
index 2c699f5da..36778ba22 100644..100755
--- a/ports/nrf/Makefile
+++ b/ports/nrf/Makefile
@@ -10,11 +10,9 @@ else
   endif
 endif
 
-# If SoftDevice is selected, try to use that one.
-# Default to SD132 (exact version can be set with SOFTDEV_VERSION)
 SD_LOWER = $(shell echo $(SD) | tr '[:upper:]' '[:lower:]')
 
-# If the build directory with SD
+# Build directory with SD
 BUILD = $(if $(SD),build-$(BOARD)-$(SD_LOWER),build-$(BOARD))
 
 include ../../py/mkenv.mk
@@ -94,19 +92,18 @@ LIBS += -L $(dir $(LIBC_FILE_NAME)) -lc
 LIBS += -L $(dir $(LIBGCC_FILE_NAME)) -lgcc
 
 SRC_HAL = $(addprefix hal/,\
-	hal_uart.c \
 	hal_rng.c \
 	)
 
 SRC_NRFX = $(addprefix nrfx/,\
+	drivers/src/nrfx_power.c \
 	drivers/src/nrfx_spim.c \
 	drivers/src/nrfx_twim.c \
-	drivers/src/nrfx_power.c \
+	drivers/src/nrfx_uart.c \
 	)
 
 SRC_C += \
 	mphalport.c \
-	help.c \
 	fatfs_port.c \
 	fifo.c \
 	tick.c \
@@ -126,12 +123,11 @@ SRC_C += \
 	lib/utils/context_manager_helpers.c \
 	lib/utils/interrupt_char.c \
 	lib/utils/pyexec.c \
+	lib/utils/stdout_helpers.c \
 	lib/libc/string0.c \
 	lib/mp-readline/readline.c \
 	internal_flash.c \
 
-#	lib/utils/stdout_helpers.c
-
 ifeq ($(MCU_SUB_VARIANT),nrf52840)
 
 SRC_C += \
@@ -233,6 +229,8 @@ SRC_SHARED_BINDINGS = \
 SRC_SHARED_MODULE_EXPANDED = $(addprefix shared-bindings/, $(SRC_SHARED_BINDINGS)) \
                              $(addprefix shared-module/, $(SRC_SHARED_MODULE))
 
+SRC_S = supervisor/cpu.s
+
 FROZEN_MPY_PY_FILES := $(shell find -L $(FROZEN_MPY_DIR) -type f -name '*.py')
 FROZEN_MPY_MPY_FILES := $(addprefix $(BUILD)/,$(FROZEN_MPY_PY_FILES:.py=.mpy))
 
@@ -243,6 +241,7 @@ OBJ += $(addprefix $(BUILD)/, $(SRC_NRFX:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(DRIVERS_SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_COMMON_HAL_EXPANDED:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_SHARED_MODULE_EXPANDED:.c=.o))
+OBJ += $(addprefix $(BUILD)/, $(SRC_S:.s=.o))
 
 $(BUILD)/$(FATFS_DIR)/ff.o: COPT += -Os
 $(filter $(PY_BUILD)/../extmod/vfs_fat_%.o, $(PY_O)): COPT += -Os
diff --git a/ports/nrf/boards/feather52832/mpconfigboard.h b/ports/nrf/boards/feather52832/mpconfigboard.h
index d0da6e398..84afc5e2d 100644
--- a/ports/nrf/boards/feather52832/mpconfigboard.h
+++ b/ports/nrf/boards/feather52832/mpconfigboard.h
@@ -25,47 +25,12 @@
  */
 
 #define MICROPY_HW_BOARD_NAME       "Bluefruit nRF52 Feather"
-#define MICROPY_HW_MCU_NAME         "NRF52832"
-#define MICROPY_PY_SYS_PLATFORM     "nrf52"
+#define MICROPY_HW_MCU_NAME         "nRF52832"
+#define MICROPY_PY_SYS_PLATFORM     "nRF52"
 
-#define MICROPY_HW_HAS_LED          (1)
-#define MICROPY_HW_HAS_SWITCH       (0)
-#define MICROPY_HW_HAS_FLASH        (0)
-#define MICROPY_HW_HAS_SDCARD       (0)
-#define MICROPY_HW_HAS_MMA7660      (0)
-#define MICROPY_HW_HAS_LIS3DSH      (0)
-#define MICROPY_HW_HAS_LCD          (0)
-#define MICROPY_HW_ENABLE_RNG       (0)
-#define MICROPY_HW_ENABLE_RTC       (0)
-#define MICROPY_HW_ENABLE_TIMER     (0)
-#define MICROPY_HW_ENABLE_SERVO     (0)
-#define MICROPY_HW_ENABLE_DAC       (0)
-#define MICROPY_HW_ENABLE_CAN       (0)
+#define MICROPY_HW_UART_RX          NRF_GPIO_PIN_MAP(0, 8)
+#define MICROPY_HW_UART_TX          NRF_GPIO_PIN_MAP(0, 6)
+#define MICROPY_HW_UART_HWFC        (0)
 
-#define MICROPY_HW_LED_COUNT        (2)
-#define MICROPY_HW_LED_PULLUP       (0)
-
-#define MICROPY_HW_LED1             (17) // LED1
-#define MICROPY_HW_LED2             (19) // LED2
-
-// UART config
-#define MICROPY_HW_UART1_RX         (pin_P0_08)
-#define MICROPY_HW_UART1_TX         (pin_P0_06)
-#define MICROPY_HW_UART1_HWFC       (0)
-
-// SPI0 config
-#define MICROPY_HW_SPI0_NAME        "SPI0"
-#define MICROPY_HW_SPI0_SCK         (pin_P0_12) // (Arduino D13)
-#define MICROPY_HW_SPI0_MOSI        (pin_P0_13) // (Arduino D11)
-#define MICROPY_HW_SPI0_MISO        (pin_P0_14) // (Arduino D12)
-
-#define MICROPY_HW_PWM0_NAME        "PWM0"
-#define MICROPY_HW_PWM1_NAME        "PWM1"
-#define MICROPY_HW_PWM2_NAME        "PWM2"
-
-#define HELP_TEXT_BOARD_LED         "1,2"
-
-
-
-#define PORT_HEAP_SIZE                (32*1024)
+#define PORT_HEAP_SIZE              (32 * 1024)
 #define CIRCUITPY_AUTORELOAD_DELAY_MS 500
diff --git a/ports/nrf/boards/feather52840/mpconfigboard.h b/ports/nrf/boards/feather52840/mpconfigboard.h
index 474fe5ace..ba9405a9d 100644
--- a/ports/nrf/boards/feather52840/mpconfigboard.h
+++ b/ports/nrf/boards/feather52840/mpconfigboard.h
@@ -27,51 +27,12 @@
 #define FEATHER52840
 
 #define MICROPY_HW_BOARD_NAME       "Feather52840"
-#define MICROPY_HW_MCU_NAME         "NRF52840"
-#define MICROPY_PY_SYS_PLATFORM     "nrf52840"
+#define MICROPY_HW_MCU_NAME         "nRF52840"
+#define MICROPY_PY_SYS_PLATFORM     "Feather52840"
 
-#define MICROPY_HW_HAS_LED          (1)
-#define MICROPY_HW_HAS_SWITCH       (0)
-#define MICROPY_HW_HAS_FLASH        (0)
-#define MICROPY_HW_HAS_SDCARD       (0)
-#define MICROPY_HW_HAS_MMA7660      (0)
-#define MICROPY_HW_HAS_LIS3DSH      (0)
-#define MICROPY_HW_HAS_LCD          (0)
-#define MICROPY_HW_ENABLE_RNG       (0)
-#define MICROPY_HW_ENABLE_RTC       (0)
-#define MICROPY_HW_ENABLE_TIMER     (0)
-#define MICROPY_HW_ENABLE_SERVO     (0)
-#define MICROPY_HW_ENABLE_DAC       (0)
-#define MICROPY_HW_ENABLE_CAN       (0)
+#define MICROPY_HW_UART_RX          NRF_GPIO_PIN_MAP(0, 8)
+#define MICROPY_HW_UART_TX          NRF_GPIO_PIN_MAP(0, 6)
+#define MICROPY_HW_UART_HWFC        (0)
 
-#define MICROPY_HW_LED_COUNT        (2)
-#define MICROPY_HW_LED_PULLUP       (1)
-
-#define MICROPY_HW_LED1             (pin_P1_02) // LED1
-#define MICROPY_HW_LED2             (pin_P1_10) // LED2
-
-// UART config
-#define MICROPY_HW_UART1_RX         (pin_P1_00)
-#define MICROPY_HW_UART1_TX         (pin_P0_24)
-#define MICROPY_HW_UART1_CTS        (NULL)
-#define MICROPY_HW_UART1_RTS        (NULL)
-#define MICROPY_HW_UART1_HWFC       (0)
-
-// SPI0 config
-#define MICROPY_HW_SPI0_NAME        "SPI0"
-
-#define MICROPY_HW_SPI0_SCK         (pin_P0_20)
-#define MICROPY_HW_SPI0_MOSI        (pin_P0_23)
-#define MICROPY_HW_SPI0_MISO        (pin_P0_22)
-
-#define MICROPY_HW_PWM0_NAME        "PWM0"
-#define MICROPY_HW_PWM1_NAME        "PWM1"
-#define MICROPY_HW_PWM2_NAME        "PWM2"
-#if 0
-#define MICROPY_HW_PWM3_NAME        "PWM3"
-#endif
-
-#define HELP_TEXT_BOARD_LED         "1,2,3,4"
-
-#define PORT_HEAP_SIZE                (128*1024)
+#define PORT_HEAP_SIZE              (128 * 1024)
 #define CIRCUITPY_AUTORELOAD_DELAY_MS 500
diff --git a/ports/nrf/boards/pca10040/mpconfigboard.h b/ports/nrf/boards/pca10040/mpconfigboard.h
index ea8000ca5..8fa001dfa 100644
--- a/ports/nrf/boards/pca10040/mpconfigboard.h
+++ b/ports/nrf/boards/pca10040/mpconfigboard.h
@@ -24,52 +24,13 @@
  * THE SOFTWARE.
  */
 
-#define PCA10040
-
 #define MICROPY_HW_BOARD_NAME       "PCA10040"
-#define MICROPY_HW_MCU_NAME         "NRF52832"
-#define MICROPY_PY_SYS_PLATFORM     "nrf52-DK"
-
-#define MICROPY_HW_HAS_LED          (1)
-#define MICROPY_HW_HAS_SWITCH       (0)
-#define MICROPY_HW_HAS_FLASH        (0)
-#define MICROPY_HW_HAS_SDCARD       (0)
-#define MICROPY_HW_HAS_MMA7660      (0)
-#define MICROPY_HW_HAS_LIS3DSH      (0)
-#define MICROPY_HW_HAS_LCD          (0)
-#define MICROPY_HW_ENABLE_RNG       (0)
-#define MICROPY_HW_ENABLE_RTC       (0)
-#define MICROPY_HW_ENABLE_TIMER     (0)
-#define MICROPY_HW_ENABLE_SERVO     (0)
-#define MICROPY_HW_ENABLE_DAC       (0)
-#define MICROPY_HW_ENABLE_CAN       (0)
-
-#define MICROPY_HW_LED_COUNT        (4)
-#define MICROPY_HW_LED_PULLUP       (1)
-
-#define MICROPY_HW_LED1             (17) // LED1
-#define MICROPY_HW_LED2             (18) // LED2
-#define MICROPY_HW_LED3             (19) // LED3
-#define MICROPY_HW_LED4             (20) // LED4
-
-// UART config
-#define MICROPY_HW_UART1_RX         (pin_P0_08)
-#define MICROPY_HW_UART1_TX         (pin_P0_06)
-#define MICROPY_HW_UART1_CTS        (pin_P0_07)
-#define MICROPY_HW_UART1_RTS        (pin_P0_05)
-#define MICROPY_HW_UART1_HWFC       (1)
-
-// SPI0 config
-#define MICROPY_HW_SPI0_NAME        "SPI0"
-#define MICROPY_HW_SPI0_SCK         (pin_P0_25) // (Arduino D13)
-#define MICROPY_HW_SPI0_MOSI        (pin_P0_23) // (Arduino D11)
-#define MICROPY_HW_SPI0_MISO        (pin_P0_24) // (Arduino D12)
-
-#define MICROPY_HW_PWM0_NAME        "PWM0"
-#define MICROPY_HW_PWM1_NAME        "PWM1"
-#define MICROPY_HW_PWM2_NAME        "PWM2"
+#define MICROPY_HW_MCU_NAME         "nRF52832"
+#define MICROPY_PY_SYS_PLATFORM     "nRF52-DK"
 
-#define HELP_TEXT_BOARD_LED         "1,2,3,4"
+#define MICROPY_HW_UART_RX          NRF_GPIO_PIN_MAP(0, 8)
+#define MICROPY_HW_UART_TX          NRF_GPIO_PIN_MAP(0, 6)
+#define MICROPY_HW_UART_HWFC        (0)
 
-#define PORT_HEAP_SIZE                (32*1024)
+#define PORT_HEAP_SIZE              (32 * 1024)
 #define CIRCUITPY_AUTORELOAD_DELAY_MS 500
diff --git a/ports/nrf/boards/pca10056/mpconfigboard.h b/ports/nrf/boards/pca10056/mpconfigboard.h
index 8ddff6c39..b85a2fc9b 100644
--- a/ports/nrf/boards/pca10056/mpconfigboard.h
+++ b/ports/nrf/boards/pca10056/mpconfigboard.h
@@ -24,58 +24,15 @@
  * THE SOFTWARE.
  */
 
-#define PCA10056
-
 #define MICROPY_HW_BOARD_NAME       "PCA10056"
-#define MICROPY_HW_MCU_NAME         "NRF52840"
-#define MICROPY_PY_SYS_PLATFORM     "nrf52840-DK"
-
-#define MICROPY_HW_HAS_LED          (1)
-#define MICROPY_HW_HAS_SWITCH       (0)
-#define MICROPY_HW_HAS_FLASH        (0)
-#define MICROPY_HW_HAS_SDCARD       (0)
-#define MICROPY_HW_HAS_MMA7660      (0)
-#define MICROPY_HW_HAS_LIS3DSH      (0)
-#define MICROPY_HW_HAS_LCD          (0)
-#define MICROPY_HW_ENABLE_RNG       (0)
-#define MICROPY_HW_ENABLE_RTC       (0)
-#define MICROPY_HW_ENABLE_TIMER     (0)
-#define MICROPY_HW_ENABLE_SERVO     (0)
-#define MICROPY_HW_ENABLE_DAC       (0)
-#define MICROPY_HW_ENABLE_CAN       (0)
-
-#define MICROPY_HW_LED_COUNT        (4)
-#define MICROPY_HW_LED_PULLUP       (1)
-
-#define MICROPY_HW_LED1             (13) // LED1
-#define MICROPY_HW_LED2             (14) // LED2
-#define MICROPY_HW_LED3             (15) // LED3
-#define MICROPY_HW_LED4             (16) // LED4
-
-// UART config
-#define MICROPY_HW_UART1_RX         (pin_P0_08)
-#define MICROPY_HW_UART1_TX         (pin_P0_06)
-#define MICROPY_HW_UART1_CTS        (pin_P0_07)
-#define MICROPY_HW_UART1_RTS        (pin_P0_05)
-#define MICROPY_HW_UART1_HWFC       (1)
-
-// SPI0 config
-#define MICROPY_HW_SPI0_NAME        "SPI0"
-
-#define MICROPY_HW_SPI0_SCK         (pin_P1_15)
-#define MICROPY_HW_SPI0_MOSI        (pin_P1_13)
-#define MICROPY_HW_SPI0_MISO        (pin_P1_14)
-
-#define MICROPY_HW_PWM0_NAME        "PWM0"
-#define MICROPY_HW_PWM1_NAME        "PWM1"
-#define MICROPY_HW_PWM2_NAME        "PWM2"
-#if 0
-#define MICROPY_HW_PWM3_NAME        "PWM3"
-#endif
+#define MICROPY_HW_MCU_NAME         "nRF52840"
+#define MICROPY_PY_SYS_PLATFORM     "nRF52840-DK"
 
-#define HELP_TEXT_BOARD_LED         "1,2,3,4"
+#define MICROPY_HW_UART_RX          NRF_GPIO_PIN_MAP(0, 8)
+#define MICROPY_HW_UART_TX          NRF_GPIO_PIN_MAP(0, 6)
+#define MICROPY_HW_UART_HWFC        (0)
 
-#define PORT_HEAP_SIZE                (128*1024)
+#define PORT_HEAP_SIZE              (128 * 1024)
 #define CIRCUITPY_AUTORELOAD_DELAY_MS 500
 
 
diff --git a/ports/nrf/common-hal/busio/I2C.c b/ports/nrf/common-hal/busio/I2C.c
index c84c763f6..f42189162 100644
--- a/ports/nrf/common-hal/busio/I2C.c
+++ b/ports/nrf/common-hal/busio/I2C.c
@@ -34,6 +34,7 @@
 #include "nrf_gpio.h"
 
 #define INST_NO 0
+#define MAX_XFER_SIZE ((1U << NRFX_CONCAT_3(TWIM, INST_NO, _EASYDMA_MAXCNT_SIZE)) - 1)
 
 static uint8_t twi_error_to_mp(const nrfx_err_t err) {
     switch (err) {
@@ -152,8 +153,21 @@ uint8_t common_hal_busio_i2c_write(busio_i2c_obj_t *self, uint16_t addr, const u
     if(len == 0)
         return common_hal_busio_i2c_probe(self, addr) ? 0 : MP_ENODEV;
 
+    const uint32_t parts = len / MAX_XFER_SIZE;
+    const uint32_t remainder = len % MAX_XFER_SIZE;
+    nrfx_err_t err = NRFX_SUCCESS;
+
     nrfx_twim_enable(&self->twim);
-    const nrfx_err_t err = nrfx_twim_tx(&self->twim, addr, data, len, !stopBit);
+
+    for (uint32_t i = 0; i < parts; ++i) {
+        err = nrfx_twim_tx(&self->twim, addr, data + i * MAX_XFER_SIZE, MAX_XFER_SIZE, !stopBit);
+        if (err != NRFX_SUCCESS)
+            break;
+    }
+
+    if ((remainder > 0) && (err == NRFX_SUCCESS))
+        err = nrfx_twim_tx(&self->twim, addr, data + parts * MAX_XFER_SIZE, remainder, !stopBit);
+
     nrfx_twim_disable(&self->twim);
 
     return twi_error_to_mp(err);
@@ -163,8 +177,21 @@ uint8_t common_hal_busio_i2c_read(busio_i2c_obj_t *self, uint16_t addr, uint8_t
     if(len == 0)
         return 0;
 
+    const uint32_t parts = len / MAX_XFER_SIZE;
+    const uint32_t remainder = len % MAX_XFER_SIZE;
+    nrfx_err_t err = NRFX_SUCCESS;
+
     nrfx_twim_enable(&self->twim);
-    const nrfx_err_t err = nrfx_twim_rx(&self->twim, addr, data, len);
+
+    for (uint32_t i = 0; i < parts; ++i) {
+        err = nrfx_twim_rx(&self->twim, addr, data + i * MAX_XFER_SIZE, MAX_XFER_SIZE);
+        if (err != NRFX_SUCCESS)
+            break;
+    }
+
+    if ((remainder > 0) && (err == NRFX_SUCCESS))
+        err = nrfx_twim_rx(&self->twim, addr, data + parts * MAX_XFER_SIZE, remainder);
+
     nrfx_twim_disable(&self->twim);
 
     return twi_error_to_mp(err);
diff --git a/ports/nrf/common-hal/busio/SPI.c b/ports/nrf/common-hal/busio/SPI.c
index d826bc026..10974c4c5 100644
--- a/ports/nrf/common-hal/busio/SPI.c
+++ b/ports/nrf/common-hal/busio/SPI.c
@@ -33,6 +33,8 @@
     #define INST_NO 2
 #endif
 
+#define MAX_XFER_SIZE ((1U << NRFX_CONCAT_3(SPIM, INST_NO, _EASYDMA_MAXCNT_SIZE)) - 1)
+
 // Convert frequency to clock-speed-dependent value
 static nrf_spim_frequency_t baudrate_to_spim_frequency(const uint32_t baudrate) {
     if (baudrate <= 125000)
@@ -152,30 +154,68 @@ bool common_hal_busio_spi_write(busio_spi_obj_t *self, const uint8_t *data, size
     if (len == 0)
         return true;
 
-    const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_XFER_TX(data, len);
-    const nrfx_err_t err = nrfx_spim_xfer(&self->spim, &xfer, 0);
+    const uint32_t parts = len / MAX_XFER_SIZE;
+    const uint32_t remainder = len % MAX_XFER_SIZE;
+
+    for (uint32_t i = 0; i < parts; ++i) {
+        const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_XFER_TX(data + i * MAX_XFER_SIZE, MAX_XFER_SIZE);
+        if (nrfx_spim_xfer(&self->spim, &xfer, 0) != NRFX_SUCCESS)
+            return false;
+    }
 
-    return (err == NRFX_SUCCESS);
+    if (remainder > 0) {
+        const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_XFER_TX(data + parts * MAX_XFER_SIZE, remainder);
+        if (nrfx_spim_xfer(&self->spim, &xfer, 0) != NRFX_SUCCESS)
+            return false;
+    }
+
+    return true;
 }
 
 bool common_hal_busio_spi_read(busio_spi_obj_t *self, uint8_t *data, size_t len, uint8_t write_value) {
     if (len == 0)
         return true;
 
-    const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_XFER_RX(data, len);
-    const nrfx_err_t err = nrfx_spim_xfer(&self->spim, &xfer, 0);
+    const uint32_t parts = len / MAX_XFER_SIZE;
+    const uint32_t remainder = len % MAX_XFER_SIZE;
+
+    for (uint32_t i = 0; i < parts; ++i) {
+        const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_XFER_RX(data + i * MAX_XFER_SIZE, MAX_XFER_SIZE);
+        if (nrfx_spim_xfer(&self->spim, &xfer, 0) != NRFX_SUCCESS)
+            return false;
+    }
 
-    return (err == NRFX_SUCCESS);
+    if (remainder > 0) {
+        const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_XFER_RX(data + parts * MAX_XFER_SIZE, remainder);
+        if (nrfx_spim_xfer(&self->spim, &xfer, 0) != NRFX_SUCCESS)
+            return false;
+    }
+
+    return true;
 }
 
 bool common_hal_busio_spi_transfer(busio_spi_obj_t *self, uint8_t *data_out, uint8_t *data_in, size_t len) {
     if (len == 0)
         return true;
 
-    const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_SINGLE_XFER(data_out, len, data_in, len);
-    const nrfx_err_t err = nrfx_spim_xfer(&self->spim, &xfer, 0);
+    const uint32_t parts = len / MAX_XFER_SIZE;
+    const uint32_t remainder = len % MAX_XFER_SIZE;
+
+    for (uint32_t i = 0; i < parts; ++i) {
+        const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_SINGLE_XFER(data_out + i * MAX_XFER_SIZE, MAX_XFER_SIZE,
+            data_in + i * MAX_XFER_SIZE, MAX_XFER_SIZE);
+        if (nrfx_spim_xfer(&self->spim, &xfer, 0) != NRFX_SUCCESS)
+            return false;
+    }
+
+    if (remainder > 0) {
+        const nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_SINGLE_XFER(data_out + parts * MAX_XFER_SIZE, remainder,
+            data_in + parts * MAX_XFER_SIZE, remainder);
+        if (nrfx_spim_xfer(&self->spim, &xfer, 0) != NRFX_SUCCESS)
+            return false;
+    }
 
-    return (err == NRFX_SUCCESS);
+    return true;
 }
 
 uint32_t common_hal_busio_spi_get_frequency(busio_spi_obj_t* self) {
diff --git a/ports/nrf/hal/hal_uart.c b/ports/nrf/hal/hal_uart.c
deleted file mode 100644
index 810449d83..000000000
--- a/ports/nrf/hal/hal_uart.c
+++ /dev/null
@@ -1,185 +0,0 @@
-/*
- * This file is part of the MicroPython project, http://micropython.org/
- *
- * The MIT License (MIT)
- *
- * Copyright (c) 2016 Glenn Ruben Bakke
- *
- * 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 "nrf.h"
-#include "mphalport.h"
-#include "hal_uart.h"
-#include "fifo.h"
-
-#include "lib/utils/interrupt_char.h"
-
-#ifdef HAL_UART_MODULE_ENABLED
-
-FIFO_DEF(_ff_uart, 128, uint8_t, true, UARTE0_UART0_IRQn);
-
-uint32_t hal_uart_baudrate_lookup[] = {
-    UART_BAUDRATE_BAUDRATE_Baud1200,   ///< 1200 baud.
-    UART_BAUDRATE_BAUDRATE_Baud2400,   ///< 2400 baud.
-    UART_BAUDRATE_BAUDRATE_Baud4800,   ///< 4800 baud.
-    UART_BAUDRATE_BAUDRATE_Baud9600,   ///< 9600 baud.
-    UART_BAUDRATE_BAUDRATE_Baud14400,  ///< 14400 baud.
-    UART_BAUDRATE_BAUDRATE_Baud19200,  ///< 19200 baud.
-    UART_BAUDRATE_BAUDRATE_Baud28800,  ///< 28800 baud.
-    UART_BAUDRATE_BAUDRATE_Baud38400,  ///< 38400 baud.
-    UART_BAUDRATE_BAUDRATE_Baud57600,  ///< 57600 baud.
-    UART_BAUDRATE_BAUDRATE_Baud76800,  ///< 76800 baud.
-    UART_BAUDRATE_BAUDRATE_Baud115200, ///< 115200 baud.
-    UART_BAUDRATE_BAUDRATE_Baud230400, ///< 230400 baud.
-    UART_BAUDRATE_BAUDRATE_Baud250000, ///< 250000 baud.
-    UART_BAUDRATE_BAUDRATE_Baud460800, ///< 460800 baud.
-    UART_BAUDRATE_BAUDRATE_Baud921600, ///< 921600 baud.
-    UART_BAUDRATE_BAUDRATE_Baud1M,     ///< 1000000 baud.
-};
-
-hal_uart_error_t hal_uart_char_write(NRF_UART_Type * p_instance, uint8_t ch) {
-    p_instance->ERRORSRC = 0;
-    p_instance->TXD   = (uint8_t)ch;
-    while (p_instance->EVENTS_TXDRDY != 1) {
-        // Blocking wait.
-    }
-
-    // Clear the TX flag.
-    p_instance->EVENTS_TXDRDY = 0;
-
-    return p_instance->ERRORSRC;
-}
-
-hal_uart_error_t hal_uart_char_read(NRF_UART_Type * p_instance, uint8_t * ch) {
-  while ( !fifo_read(_ff_uart, ch) ) {
-    // wait for fifo data
-  }
-
-  return HAL_UART_ERROR_NONE;
-}
-
-hal_uart_error_t hal_uart_buffer_write(NRF_UART_Type * p_instance, uint8_t * p_buffer, uint32_t num_of_bytes, uart_complete_cb cb) {
-    int i = 0;
-    hal_uart_error_t err = 0;
-    uint8_t ch = p_buffer[i++];
-    while (i < num_of_bytes) {
-        err = hal_uart_char_write(p_instance, ch);
-        if (err) {
-            return err;
-        }
-        ch = p_buffer[i++];
-    }
-    cb();
-    return err;
-}
-
-hal_uart_error_t hal_uart_buffer_read(NRF_UART_Type * p_instance, uint8_t * p_buffer, uint32_t num_of_bytes, uart_complete_cb cb) {
-    int i = 0;
-    hal_uart_error_t err = 0;
-    while (i < num_of_bytes) {
-        hal_uart_error_t err = hal_uart_char_read(p_instance, &p_buffer[i]);
-        if (err) {
-            return err;
-        }
-        i++;
-    }
-    cb();
-    return err;
-}
-
-int hal_uart_available(NRF_UART_Type * p_instance)
-{
-  return fifo_count(_ff_uart);
-}
-
-void hal_uart_init(NRF_UART_Type * p_instance, hal_uart_init_t const * p_uart_init) {
-    hal_gpio_cfg_pin(p_uart_init->tx_pin->port, p_uart_init->tx_pin->pin, HAL_GPIO_MODE_OUTPUT, HAL_GPIO_PULL_DISABLED);
-    hal_gpio_cfg_pin(p_uart_init->rx_pin->port, p_uart_init->rx_pin->pin, HAL_GPIO_MODE_INPUT, HAL_GPIO_PULL_DISABLED);
-
-    hal_gpio_pin_clear(p_uart_init->tx_pin->port, p_uart_init->tx_pin->pin);
-
-    p_instance->PSELTXD = p_uart_init->tx_pin->pin;
-    p_instance->PSELRXD = p_uart_init->rx_pin->pin;
-
-#if NRF52840_XXAA
-    p_instance->PSELTXD |= (p_uart_init->tx_pin->port << UARTE_PSEL_TXD_PORT_Pos);
-    p_instance->PSELRXD |= (p_uart_init->rx_pin->port << UARTE_PSEL_RXD_PORT_Pos);
-#endif
-
-    if (p_uart_init->flow_control) {
-        hal_gpio_cfg_pin(p_uart_init->rts_pin->port, p_uart_init->rts_pin->pin, HAL_GPIO_MODE_OUTPUT, HAL_GPIO_PULL_DISABLED);
-        hal_gpio_cfg_pin(p_uart_init->cts_pin->port, p_uart_init->cts_pin->pin, HAL_GPIO_MODE_INPUT, HAL_GPIO_PULL_DISABLED);
-
-        p_instance->PSELCTS = p_uart_init->cts_pin->pin;
-        p_instance->PSELRTS = p_uart_init->rts_pin->pin;
-
-#if NRF52840_XXAA
-        p_instance->PSELCTS |= (p_uart_init->cts_pin->port << UARTE_PSEL_CTS_PORT_Pos);
-        p_instance->PSELRTS |= (p_uart_init->rts_pin->port << UARTE_PSEL_RTS_PORT_Pos);
-#endif
-
-        p_instance->CONFIG  = (UART_CONFIG_HWFC_Enabled << UART_CONFIG_HWFC_Pos);
-    }
-
-    p_instance->BAUDRATE      = (hal_uart_baudrate_lookup[p_uart_init->baud_rate]);
-    p_instance->ENABLE        = (UART_ENABLE_ENABLE_Enabled << UART_ENABLE_ENABLE_Pos);
-    p_instance->EVENTS_TXDRDY = 0;
-    p_instance->EVENTS_RXDRDY = 0;
-    p_instance->TASKS_STARTTX = 1;
-    p_instance->TASKS_STARTRX = 1;
-
-    // Adafruit IRQ + fifo
-    fifo_clear(_ff_uart);
-    p_instance->INTENSET = UART_INTENSET_RXDRDY_Msk;
-    NVIC_ClearPendingIRQ(p_uart_init->irq_num);
-    NVIC_SetPriority(p_uart_init->irq_num, p_uart_init->irq_priority);
-    NVIC_EnableIRQ(p_uart_init->irq_num);
-}
-
-bool hal_uart_inited(NRF_UART_Type * p_instance)
-{
-    return !(p_instance->PSELTXD & (1 << 31)) && !(p_instance->PSELRXD & (1 << 31));
-}
-
-void UARTE0_UART0_IRQHandler(void)
-{
-  NRF_UART_Type * p_instance = NRF_UART0;
-
-  if (p_instance->EVENTS_RXDRDY)
-  {
-    uint8_t ch = (uint8_t) p_instance->RXD;
-
-    // Keyboard interrupt
-    if (mp_interrupt_char != -1 && ch == mp_interrupt_char)
-    {
-      mp_keyboard_interrupt();
-    }else
-    {
-      fifo_write(_ff_uart, &ch);
-    }
-
-    p_instance->EVENTS_RXDRDY = 0x0UL;
-  }
-}
-
-#endif // HAL_UART_MODULE_ENABLED
diff --git a/ports/nrf/hal/hal_uart.h b/ports/nrf/hal/hal_uart.h
deleted file mode 100644
index 97b5487ed..000000000
--- a/ports/nrf/hal/hal_uart.h
+++ /dev/null
@@ -1,114 +0,0 @@
-/*
- * This file is part of the MicroPython project, http://micropython.org/
- *
- * The MIT License (MIT)
- *
- * Copyright (c) 2016 Glenn Ruben Bakke
- *
- * 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 HAL_UART_H__
-#define HAL_UART_H__
-
-#include <stdint.h>
-#include <stdbool.h>
-
-#include "nrf.h"
-
-#define UART_HWCONTROL_NONE                  ((uint32_t)UARTE_CONFIG_HWFC_Disabled << UARTE_CONFIG_HWFC_Pos)
-#define UART_HWCONTROL_RTS_CTS               ((uint32_t)(UARTE_CONFIG_HWFC_Enabled << UARTE_CONFIG_HWFC_Pos)
-#define IS_UART_HARDWARE_FLOW_CONTROL(CONTROL)\
-                            (((CONTROL) == UART_HWCONTROL_NONE) || \
-                             ((CONTROL) == UART_HWCONTROL_RTS_CTS))
-#ifdef HAL_UART_MODULE_ENABLED
-  #define UART_BASE_POINTERS (const uint32_t[]){NRF_UART0_BASE}
-  #define UART_IRQ_VALUES (const uint32_t[]){UARTE0_UART0_IRQn}
-#else // HAL_UARTE_MODULE_ENABLED
-  #ifdef NRF52832_XXAA
-    #define UART_BASE_POINTERS (const uint32_t[]){NRF_UARTE0_BASE}
-    #define UART_IRQ_VALUES (const uint32_t[]){UARTE0_UART0_IRQn}
-  #elif NRF52840_XXAA
-    #define UART_BASE_POINTERS (const uint32_t[]){NRF_UARTE0_BASE, \
-                                                  NRF_UARTE1_BASE}
-    #define UART_IRQ_VALUES (const uint32_t[]){UARTE0_UART0_IRQn, \
-                                               UARTE1_IRQn}
-  #endif // HAL_UARTE_MODULE_ENABLED
-#endif
-
-#define UART_BASE(x) ((NRF_UART_Type *)UART_BASE_POINTERS[x])
-#define UART_IRQ_NUM(x) (UART_IRQ_VALUES[x])
-
-typedef enum
-{
-    HAL_UART_ERROR_NONE      = 0x00,    /*!< No error */
-    HAL_UART_ERROR_ORE       = 0x01,    /*!< Overrun error. A start bit is received while the previous data still lies in RXD. (Previous data is lost.) */
-    HAL_UART_ERROR_PE        = 0x02,    /*!< Parity error. A character with bad parity is received, if HW parity check is enabled. */
-    HAL_UART_ERROR_FE        = 0x04,    /*!< Frame error. A valid stop bit is not detected on the serial data input after all bits in a character have been received. */
-    HAL_UART_ERROR_BE        = 0x08,    /*!< Break error. The serial data input is '0' for longer than the length of a data frame. (The data frame length is 10 bits without parity bit, and 11 bits with parity bit.). */
-} hal_uart_error_t;
-
-typedef enum {
-    HAL_UART_BAUD_1K2 = 0,        /**< 1200 baud */
-    HAL_UART_BAUD_2K4,            /**< 2400 baud */
-    HAL_UART_BAUD_4K8,            /**< 4800 baud */
-    HAL_UART_BAUD_9K6,            /**< 9600 baud */
-    HAL_UART_BAUD_14K4,           /**< 14.4 kbaud */
-    HAL_UART_BAUD_19K2,           /**< 19.2 kbaud */
-    HAL_UART_BAUD_28K8,           /**< 28.8 kbaud */
-    HAL_UART_BAUD_38K4,           /**< 38.4 kbaud */
-    HAL_UART_BAUD_57K6,           /**< 57.6 kbaud */
-    HAL_UART_BAUD_76K8,           /**< 76.8 kbaud */
-    HAL_UART_BAUD_115K2,          /**< 115.2 kbaud */
-    HAL_UART_BAUD_230K4,          /**< 230.4 kbaud */
-    HAL_UART_BAUD_250K0,          /**< 250.0 kbaud */
-    HAL_UART_BAUD_500K0,          /**< 500.0 kbaud */
-    HAL_UART_BAUD_1M0             /**< 1 mbaud */
-} hal_uart_baudrate_t;
-
-typedef struct {
-    uint8_t           id;           /* UART instance id */
-    const pin_obj_t * rx_pin;       /* RX pin. */
-    const pin_obj_t * tx_pin;       /* TX pin. */
-    const pin_obj_t * rts_pin;      /* RTS pin, only used if flow control is enabled. */
-    const pin_obj_t * cts_pin;      /* CTS pin, only used if flow control is enabled. */
-    bool              flow_control; /* Flow control setting, if flow control is used, the system will use low power UART mode, based on CTS signal. */
-    bool              use_parity;   /* Even parity if TRUE, no parity if FALSE. */
-    uint32_t          baud_rate;    /* Baud rate configuration. */
-    uint32_t          irq_priority; /* UARTE IRQ priority. */
-    uint32_t          irq_num;
-} hal_uart_init_t;
-
-typedef struct
-{
-    NRF_UART_Type     * p_instance; /* UART registers base address   */
-    hal_uart_init_t     init;       /* UART communication parameters */
-} UART_HandleTypeDef;
-
-typedef void (*uart_complete_cb)(void);
-
-void hal_uart_init(NRF_UART_Type * p_instance, hal_uart_init_t const * p_uart_init);
-bool hal_uart_inited(NRF_UART_Type * p_instance);
-
-hal_uart_error_t hal_uart_char_write(NRF_UART_Type * p_instance, uint8_t ch);
-
-hal_uart_error_t hal_uart_char_read(NRF_UART_Type * p_instance, uint8_t * ch);
-int hal_uart_available(NRF_UART_Type * p_instance);
-
-#endif // HAL_UART_H__
diff --git a/ports/nrf/mpconfigport.h b/ports/nrf/mpconfigport.h
index 9fb8f68ee..24f41db0e 100644
--- a/ports/nrf/mpconfigport.h
+++ b/ports/nrf/mpconfigport.h
@@ -93,8 +93,8 @@
 #define MICROPY_PY_BUILTINS_EXECFILE             (0)
 #define MICROPY_PY_BUILTINS_COMPILE              (1)
 #define MICROPY_PY_BUILTINS_HELP                 (1)
-#define MICROPY_PY_BUILTINS_HELP_TEXT            nrf5_help_text
 #define MICROPY_PY_BUILTINS_HELP_MODULES         (1)
+#define MICROPY_PY_BUILTINS_HELP_TEXT            circuitpython_help_text
 #define MICROPY_PY_BUILTINS_INPUT                (1)
 #define MICROPY_MODULE_BUILTIN_INIT              (1)
 #define MICROPY_PY_ALL_SPECIAL_METHODS           (0)
@@ -126,14 +126,6 @@
 
 #define MICROPY_KBD_EXCEPTION                    (1)
 
-#ifndef MICROPY_HW_LED_COUNT
-#define MICROPY_HW_LED_COUNT                     (0)
-#endif
-
-#ifndef MICROPY_HW_LED_PULLUP
-#define MICROPY_HW_LED_PULLUP                    (0)
-#endif
-
 #ifndef MICROPY_PY_HW_RNG
 #define MICROPY_PY_HW_RNG                        (1)
 #endif
diff --git a/ports/nrf/mphalport.c b/ports/nrf/mphalport.c
index 8846c2b30..2266f84a2 100644
--- a/ports/nrf/mphalport.c
+++ b/ports/nrf/mphalport.c
@@ -4,6 +4,7 @@
  * The MIT License (MIT)
  *
  * Copyright (c) 2015 Glenn Ruben Bakke
+ * Copyright (c) 2018 Artur Pacholec
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -27,73 +28,36 @@
 #include <errno.h>
 #include <string.h>
 
+#include "mphalport.h"
 #include "py/mpstate.h"
-#include "py/mphal.h"
-#include "py/mperrno.h"
 
-#include "tick.h"
-
-#if !defined( NRF52840_XXAA) || ( defined(CFG_HWUART_FOR_SERIAL) && CFG_HWUART_FOR_SERIAL == 1 )
-#include "hal_uart.h"
-
-#define UART_INSTANCE   UART_BASE(0)
 
 #if (MICROPY_PY_BLE_NUS == 0)
+
+#if !defined( NRF52840_XXAA) || ( defined(CFG_HWUART_FOR_SERIAL) && CFG_HWUART_FOR_SERIAL == 1 )
 int mp_hal_stdin_rx_chr(void) {
-    for (;;) {
-        #ifdef MICROPY_VM_HOOK_LOOP
-            MICROPY_VM_HOOK_LOOP
-        #endif
-        // if (reload_requested) {
-        //     return CHAR_CTRL_D;
-        // }
+    uint8_t data = 0;
 
-        if ( hal_uart_available(UART_INSTANCE) ) {
-          uint8_t ch;
-          hal_uart_char_read(UART_INSTANCE, &ch);
-          return (int) ch;
-        }
-    }
+    while (!nrfx_uart_rx_ready(&serial_instance));
 
-    return 0;
+    const nrfx_err_t err = nrfx_uart_rx(&serial_instance, &data, sizeof(data));
+    if (err == NRFX_SUCCESS)
+        NRFX_ASSERT(err);
+
+    return data;
 }
 
 bool mp_hal_stdin_any(void) {
-  return hal_uart_available(UART_INSTANCE);
+    return nrfx_uart_rx_ready(&serial_instance);
 }
 
 void mp_hal_stdout_tx_strn(const char *str, mp_uint_t len) {
+    if (len == 0)
+        return;
 
-//    #ifdef MICROPY_HW_LED_TX
-//    gpio_toggle_pin_level(MICROPY_HW_LED_TX);
-//    #endif
-//
-//    #ifdef CIRCUITPY_BOOT_OUTPUT_FILE
-//    if (boot_output_file != NULL) {
-//        UINT bytes_written = 0;
-//        f_write(boot_output_file, str, len, &bytes_written);
-//    }
-//    #endif
-
-    if ( hal_uart_inited(UART_INSTANCE) ) {
-        while(len--) {
-            hal_uart_char_write(UART_INSTANCE, *str++);
-        }
-    }
-}
-
-void mp_hal_stdout_tx_strn_cooked(const char *str, mp_uint_t len) {
-  while(len--){
-    if (*str == '\n') {
-      hal_uart_char_write(UART_INSTANCE, '\r');
-    }
-    hal_uart_char_write(UART_INSTANCE, *str++);
-  }
-}
-#endif
-
-void mp_hal_stdout_tx_str(const char *str) {
-    mp_hal_stdout_tx_strn(str, strlen(str));
+    const nrfx_err_t err = nrfx_uart_tx(&serial_instance, (uint8_t*)str, len);
+    if (err == NRFX_SUCCESS)
+        NRFX_ASSERT(err);
 }
 
 #else
@@ -140,22 +104,14 @@ void mp_hal_stdout_tx_strn(const char *str, mp_uint_t len) {
     tud_cdc_write(str, len);
 }
 
-// TODO use stdout_helper.c
-void mp_hal_stdout_tx_strn_cooked(const char *str, size_t len) {
-    while (len--) {
-        if (*str == '\n') {
-            mp_hal_stdout_tx_strn("\r", 1);
-        }
-        mp_hal_stdout_tx_strn(str++, 1);
-    }
-}
+#endif // USB
 
-void mp_hal_stdout_tx_str(const char *str) {
-    mp_hal_stdout_tx_strn(str, strlen(str));
-}
+#endif // NUS
 
-#endif
 
+/*------------------------------------------------------------------*/
+/* delay
+ *------------------------------------------------------------------*/
 void mp_hal_delay_ms(mp_uint_t delay) {
     uint64_t start_tick = ticks_ms;
     uint64_t duration = 0;
@@ -249,4 +205,3 @@ void mp_hal_delay_us(mp_uint_t us)
 }
 
 
-
diff --git a/ports/nrf/mphalport.h b/ports/nrf/mphalport.h
index 3334fd7fe..a217d8896 100644
--- a/ports/nrf/mphalport.h
+++ b/ports/nrf/mphalport.h
@@ -27,53 +27,28 @@
 #ifndef __NRF52_HAL
 #define __NRF52_HAL
 
-#include "py/mpconfig.h"
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "hal_gpio.h"
+#include "lib/utils/interrupt_char.h"
+#include "nrf.h"
 #include NRF5_HAL_H
+#include "nrfx_uart.h"
 #include "pin.h"
-#include "hal_gpio.h"
-
-#include "lib/oofatfs/ff.h"
+#include "py/mpconfig.h"
 
-typedef enum
-{
-  HAL_OK       = 0x00,
-  HAL_ERROR    = 0x01,
-  HAL_BUSY     = 0x02,
-  HAL_TIMEOUT  = 0x03
-} HAL_StatusTypeDef;
+extern nrfx_uart_t serial_instance;
 
-extern FIL* boot_output_file;
+extern volatile uint64_t ticks_ms;
 
-static inline uint32_t hal_tick_fake(void) {
-	return 0;
+static inline mp_uint_t mp_hal_ticks_ms(void) {
+    return ticks_ms;
 }
 
-#define mp_hal_ticks_ms hal_tick_fake // TODO: implement. Right now, return 0 always
-
-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
-
 int mp_hal_stdin_rx_chr(void);
 void mp_hal_stdout_tx_str(const char *str);
 bool mp_hal_stdin_any(void);
 
-#define mp_hal_pin_obj_t const pin_obj_t*
-#define mp_hal_get_pin_obj(o)    pin_find(o)
-#define mp_hal_pin_high(p)       hal_gpio_pin_high(p)
-#define mp_hal_pin_low(p)        hal_gpio_pin_low(p)
-#define mp_hal_pin_read(p)       hal_gpio_pin_read(p)
-#define mp_hal_pin_write(p, v)   do { if (v) { mp_hal_pin_high(p); } else { mp_hal_pin_low(p); } } while (0)
-#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_open_drain(p) hal_gpio_cfg_pin(p->port, p->pin, HAL_GPIO_MODE_INPUT, HAL_GPIO_PULL_DISABLED)
-
-
-// TODO: empty implementation for now. Used by machine_spi.c:69
-#define mp_hal_delay_us_fast(p)
-#define mp_hal_ticks_us() (0)
-#define mp_hal_ticks_cpu() (0)
-
 #endif
 
diff --git a/ports/nrf/nrfx_config.h b/ports/nrf/nrfx_config.h
index a30fb343f..88fb973e8 100644
--- a/ports/nrf/nrfx_config.h
+++ b/ports/nrf/nrfx_config.h
@@ -1,6 +1,10 @@
 #ifndef NRFX_CONFIG_H__
 #define NRFX_CONFIG_H__
 
+// Power
+#define NRFX_POWER_ENABLED 1
+#define NRFX_POWER_CONFIG_IRQ_PRIORITY 7
+
 // SPI
 #define NRFX_SPIM_ENABLED 1
 
@@ -21,7 +25,13 @@
 #define NRFX_TWIM_DEFAULT_CONFIG_FREQUENCY NRF_TWIM_FREQ_400K
 #define NRFX_TWIM_DEFAULT_CONFIG_HOLD_BUS_UNINIT 0
 
-#define NRFX_POWER_ENABLED 1
-#define NRFX_POWER_CONFIG_IRQ_PRIORITY 7
+// UART
+#define NRFX_UART_ENABLED 1
+#define NRFX_UART0_ENABLED 1
+
+#define NRFX_UART_DEFAULT_CONFIG_IRQ_PRIORITY 7
+#define NRFX_UART_DEFAULT_CONFIG_HWFC NRF_UART_HWFC_DISABLED
+#define NRFX_UART_DEFAULT_CONFIG_PARITY NRF_UART_PARITY_EXCLUDED
+#define NRFX_UART_DEFAULT_CONFIG_BAUDRATE NRF_UART_BAUDRATE_115200
 
 #endif
diff --git a/ports/nrf/supervisor/cpu.s b/ports/nrf/supervisor/cpu.s
new file mode 100755
index 000000000..9e6807a5e
--- /dev/null
+++ b/ports/nrf/supervisor/cpu.s
@@ -0,0 +1,27 @@
+.syntax unified
+.cpu cortex-m4
+.thumb
+.text
+.align  2
+
+@ uint cpu_get_regs_and_sp(r0=uint regs[10])
+.global cpu_get_regs_and_sp
+.thumb
+.thumb_func
+.type   cpu_get_regs_and_sp, %function
+cpu_get_regs_and_sp:
+@ store registers into given array
+str     r4, [r0], #4
+str     r5, [r0], #4
+str     r6, [r0], #4
+str     r7, [r0], #4
+str     r8, [r0], #4
+str     r9, [r0], #4
+str     r10, [r0], #4
+str     r11, [r0], #4
+str     r12, [r0], #4
+str     r13, [r0], #4
+
+@ return the sp
+mov     r0, sp
+bx      lr
diff --git a/ports/nrf/supervisor/serial.c b/ports/nrf/supervisor/serial.c
index e6c43b58a..4256b39f1 100644
--- a/ports/nrf/supervisor/serial.c
+++ b/ports/nrf/supervisor/serial.c
@@ -24,51 +24,46 @@
  * THE SOFTWARE.
  */
 
-#include "supervisor/serial.h"
-
-#include "py/obj.h"
-#include "py/runtime.h"
 #include "mphalport.h"
-#include "pins.h"
-#include "hal_uart.h"
 
-#if (MICROPY_PY_BLE_NUS)
+#if MICROPY_PY_BLE_NUS
 #include "ble_uart.h"
+#else
+#include "nrf_gpio.h"
+#include "pin.h"
 #endif
 
 #if !defined( NRF52840_XXAA) || ( defined(CFG_HWUART_FOR_SERIAL) && CFG_HWUART_FOR_SERIAL == 1 )
 
-void serial_init(void) {
+#define INST_NO 0
 
+nrfx_uart_t serial_instance = NRFX_UART_INSTANCE(INST_NO);
+
+void serial_init(void) {
 #if MICROPY_PY_BLE_NUS
     ble_uart_init0();
     while (!ble_uart_enabled()) {
         ;
     }
 #else
-  hal_uart_init_t param =
-  {
-      .id           = 0,
-      .rx_pin       = &MICROPY_HW_UART1_RX,
-      .tx_pin       = &MICROPY_HW_UART1_TX,
-#if MICROPY_HW_UART1_HWFC
-      .rts_pin      = &MICROPY_HW_UART1_RTS,
-      .cts_pin      = &MICROPY_HW_UART1_CTS,
-#else
-      .rts_pin      = NULL,
-      .cts_pin      = NULL,
+    nrfx_uart_config_t config = NRFX_UART_DEFAULT_CONFIG;
+    config.pseltxd = MICROPY_HW_UART_TX;
+    config.pselrxd = MICROPY_HW_UART_RX;
+    config.hwfc = MICROPY_HW_UART_HWFC ? NRF_UART_HWFC_ENABLED : NRF_UART_HWFC_DISABLED;
+#ifdef MICROPY_HW_UART_CTS
+    config.pselcts = MICROPY_HW_UART_CTS;
 #endif
-      .flow_control = MICROPY_HW_UART1_HWFC ? true : false,
-      .use_parity   = false,
-      .baud_rate    = HAL_UART_BAUD_115K2,
-      .irq_priority = 6,
-      .irq_num      = UARTE0_UART0_IRQn
-  };
-
-  hal_uart_init( UART_BASE(0), &param);
+#ifdef MICROPY_HW_UART_RTS
+    config.pselrts = MICROPY_HW_UART_RTS;
 #endif
-}
 
+    const nrfx_err_t err = nrfx_uart_init(&serial_instance, &config, NULL);
+    if (err == NRFX_SUCCESS)
+        NRFX_ASSERT(err);
+
+    nrfx_uart_rx_enable(&serial_instance);
+#endif
+}
 
 bool serial_connected(void) {
     return true;
@@ -82,8 +77,8 @@ bool serial_bytes_available(void) {
     return mp_hal_stdin_any();
 }
 
-void serial_write(const char* text) {
-  mp_hal_stdout_tx_str(text);
+void serial_write(const char *text) {
+    mp_hal_stdout_tx_str(text);
 }
 
 #else
@@ -112,4 +107,3 @@ void serial_write(const char* text) {
 }
 
 #endif
-
diff --git a/py/builtinimport.c b/py/builtinimport.c
index 9f7d34dca..c1437da4c 100644..100755
--- a/py/builtinimport.c
+++ b/py/builtinimport.c
@@ -31,6 +31,7 @@
 
 #include "py/compile.h"
 #include "py/gc_long_lived.h"
+#include "py/gc.h"
 #include "py/objmodule.h"
 #include "py/persistentcode.h"
 #include "py/runtime.h"
@@ -468,6 +469,10 @@ mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
                     // (the module that was just loaded) is not a package.  This will be caught
                     // on the next iteration because the file will not exist.
                 }
+
+                // Loading a module thrashes the heap significantly so we explicitly clean up
+                // afterwards.
+                gc_collect();
             }
             if (outer_module_obj != MP_OBJ_NULL) {
                 qstr s = qstr_from_strn(mod_str + last, i - last);
diff --git a/py/gc.c b/py/gc.c
index 2c2354e4c..2c2354e4c 100644..100755
--- a/py/gc.c
+++ b/py/gc.c
diff --git a/py/gc_long_lived.c b/py/gc_long_lived.c
index d34fde5d9..e30b389fa 100644..100755
--- a/py/gc_long_lived.c
+++ b/py/gc_long_lived.c
@@ -121,7 +121,7 @@ mp_obj_t make_obj_long_lived(mp_obj_t obj, uint8_t max_depth){
     } else if (MP_OBJ_IS_TYPE(obj, &mp_type_property)) {
         mp_obj_property_t *prop = MP_OBJ_TO_PTR(obj);
         return MP_OBJ_FROM_PTR(make_property_long_lived(prop, max_depth));
-    } else if (MP_OBJ_IS_TYPE(obj, &mp_type_str)) {
+    } else if (MP_OBJ_IS_TYPE(obj, &mp_type_str) || MP_OBJ_IS_TYPE(obj, &mp_type_bytes)) {
         mp_obj_str_t *str = MP_OBJ_TO_PTR(obj);
         return MP_OBJ_FROM_PTR(make_str_long_lived(str));
     } else if (MP_OBJ_IS_TYPE(obj, &mp_type_type)) {
diff --git a/py/mpconfig.h b/py/mpconfig.h
index 765ae1e8f..74d7c2c92 100644..100755
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -130,6 +130,12 @@
 #define MICROPY_ALLOC_QSTR_CHUNK_INIT (128)
 #endif
 
+// Max number of entries in newly allocated QSTR pools. Smaller numbers may make QSTR lookups
+// slightly slower but reduce the waste of unused spots.
+#ifndef MICROPY_QSTR_POOL_MAX_ENTRIES
+#define MICROPY_QSTR_POOL_MAX_ENTRIES (64)
+#endif
+
 // Initial amount for lexer indentation level
 #ifndef MICROPY_ALLOC_LEXER_INDENT_INIT
 #define MICROPY_ALLOC_LEXER_INDENT_INIT (10)
diff --git a/py/qstr.c b/py/qstr.c
index 49b2d9daa..de4dc6240 100644..100755
--- a/py/qstr.c
+++ b/py/qstr.c
@@ -144,14 +144,18 @@ STATIC qstr qstr_add(const byte *q_ptr) {
 
     // make sure we have room in the pool for a new qstr
     if (MP_STATE_VM(last_pool)->len >= MP_STATE_VM(last_pool)->alloc) {
-        qstr_pool_t *pool = m_new_ll_obj_var_maybe(qstr_pool_t, const char*, MP_STATE_VM(last_pool)->alloc * 2);
+        uint32_t new_pool_length = MP_STATE_VM(last_pool)->alloc * 2;
+        if (new_pool_length > MICROPY_QSTR_POOL_MAX_ENTRIES) {
+            new_pool_length = MICROPY_QSTR_POOL_MAX_ENTRIES;
+        }
+        qstr_pool_t *pool = m_new_ll_obj_var_maybe(qstr_pool_t, const char*, new_pool_length);
         if (pool == NULL) {
             QSTR_EXIT();
-            m_malloc_fail(MP_STATE_VM(last_pool)->alloc * 2);
+            m_malloc_fail(new_pool_length);
         }
         pool->prev = MP_STATE_VM(last_pool);
         pool->total_prev_len = MP_STATE_VM(last_pool)->total_prev_len + MP_STATE_VM(last_pool)->len;
-        pool->alloc = MP_STATE_VM(last_pool)->alloc * 2;
+        pool->alloc = new_pool_length;
         pool->len = 0;
         MP_STATE_VM(last_pool) = pool;
         DEBUG_printf("QSTR: allocate new pool of size %d\n", MP_STATE_VM(last_pool)->alloc);
diff --git a/ports/nrf/help.c b/supervisor/cpu.h
index 5cbb0fc91..c4f81316c 100644..100755
--- a/ports/nrf/help.c
+++ b/supervisor/cpu.h
@@ -3,8 +3,7 @@
  *
  * The MIT License (MIT)
  *
- * Copyright (c) 2013, 2014 Damien P. George
- * Copyright (c) 2016 Glenn Ruben Bakke
+ * Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -25,30 +24,11 @@
  * THE SOFTWARE.
  */
 
-#include "py/builtin.h"
+#ifndef MICROPY_INCLUDED_SUPERVISOR_CPU_H
+#define MICROPY_INCLUDED_SUPERVISOR_CPU_H
 
-#if BLUETOOTH_SD
-#include "help_sd.h"
-#endif
+// Adds up to 10 pointers from the CPUs registers to regs. This is used to make sure no actively
+// used heap memory is freed. Its usually implemented in assembly.
+mp_uint_t cpu_get_regs_and_sp(mp_uint_t *regs);
 
-const char nrf5_help_text[] =
-"Welcome to MicroPython!\n"
-"\n"
-"For online help please visit http://micropython.org/help/.\n"
-"\n"
-"Quick overview of commands for the board:\n"
-#if MICROPY_HW_HAS_LED
-"  pyb.LED(n)    -- create an LED object for LED n (n=" HELP_TEXT_BOARD_LED ")\n"
-"\n"
-#endif
-#if BLUETOOTH_SD
-HELP_TEXT_SD
-#endif
-"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-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"
-;
+#endif  // MICROPY_INCLUDED_SUPERVISOR_CPU_H
diff --git a/tools/analyze_heap_dump.py b/tools/analyze_heap_dump.py
index 55342ac69..31202c23e 100644..100755
--- a/tools/analyze_heap_dump.py
+++ b/tools/analyze_heap_dump.py
@@ -135,8 +135,11 @@ def do_all_the_things(ram_filename, bin_filename, map_filename, print_block_cont
     ram_start = symbols["_srelocate"][0]
     ram_end = symbols["_estack"][0]
     ram_length = ram_end - ram_start
+    # print(ram_length, "ram length")
+    # print(len(ram_dump) // ram_length, "snapshots")
     if analyze_snapshots == "all":
         snapshots = range(len(ram_dump) // ram_length - 1, -1, -1)
+        #snapshots = range(4576, -1, -1)
     elif analyze_snapshots == "last":
         snapshots = range(len(ram_dump) // ram_length - 1, len(ram_dump) // ram_length - 2, -1)
     for snapshot_num in snapshots:
@@ -167,16 +170,16 @@ def do_all_the_things(ram_filename, bin_filename, map_filename, print_block_cont
         mp_state_ctx = symbols["mp_state_ctx"][0]
         manual_symbol_map["mp_state_ctx+20"] = "mp_state_ctx.vm.last_pool"
         last_pool = load_pointer(mp_state_ctx + 20) # (gdb) p &mp_state_ctx.vm.last_pool
-        manual_symbol_map["mp_state_ctx+88"] = "mp_state_ctx.vm.dict_main.map.table"
-        dict_main_table = load_pointer(mp_state_ctx + 88) # (gdb) p &mp_state_ctx.vm.dict_main.map.table
-        manual_symbol_map["mp_state_ctx+68"] = "mp_state_ctx.vm.mp_loaded_modules_dict.map.table"
-        imports_table = load_pointer(mp_state_ctx + 68) # (gdb) p &mp_state_ctx.vm.mp_loaded_modules_dict.map.table
+        manual_symbol_map["mp_state_ctx+104"] = "mp_state_ctx.vm.dict_main.map.table"
+        dict_main_table = load_pointer(mp_state_ctx + 104) # (gdb) p &mp_state_ctx.vm.dict_main.map.table
+        manual_symbol_map["mp_state_ctx+84"] = "mp_state_ctx.vm.mp_loaded_modules_dict.map.table"
+        imports_table = load_pointer(mp_state_ctx + 84) # (gdb) p &mp_state_ctx.vm.mp_loaded_modules_dict.map.table
 
-        manual_symbol_map["mp_state_ctx+104"] = "mp_state_ctx.vm.mp_sys_path_obj.items"
-        manual_symbol_map["mp_state_ctx+120"] = "mp_state_ctx.vm.mp_sys_argv_obj.items"
+        manual_symbol_map["mp_state_ctx+120"] = "mp_state_ctx.vm.mp_sys_path_obj.items"
+        manual_symbol_map["mp_state_ctx+136"] = "mp_state_ctx.vm.mp_sys_argv_obj.items"
 
         for i in range(READLINE_HIST_SIZE):
-            manual_symbol_map["mp_state_ctx+{}".format(128 + i * 4)] = "mp_state_ctx.vm.readline_hist[{}]".format(i)
+            manual_symbol_map["mp_state_ctx+{}".format(144 + i * 4)] = "mp_state_ctx.vm.readline_hist[{}]".format(i)
 
         tuple_type = symbols["mp_type_tuple"][0]
         type_type = symbols["mp_type_type"][0]
@@ -214,8 +217,8 @@ def do_all_the_things(ram_filename, bin_filename, map_filename, print_block_cont
         pool_start = heap_start + total_byte_len - pool_length - pool_shift
         pool = heap[-pool_length-pool_shift:]
 
-        total_height = 65 * 18
-        total_width = (pool_length // (64 * 16)) * 90
+        total_height = 128 * 18
+        total_width = (pool_length // (128 * 16)) * 85
 
         map_element_blocks = [dict_main_table, imports_table]
         string_blocks = []
@@ -255,10 +258,11 @@ def do_all_the_things(ram_filename, bin_filename, map_filename, print_block_cont
             block_data[address] = data
             for k in range(len(data) // 4):
                 word = struct.unpack_from("<I", data, offset=(k * 4))[0]
-                if word < 0x00040000 and k == 0 or address in qstr_pools:
+                if word < len(rom) and k == 0 or address in qstr_pools:
                     potential_type = word
                     bgcolor = "gray"
                     if address in qstr_pools:
+                        #print(address, len(data))
                         bgcolor = "tomato"
                     elif potential_type in function_types:
                         bgcolor = "green"
@@ -292,11 +296,11 @@ def do_all_the_things(ram_filename, bin_filename, map_filename, print_block_cont
                 if potential_type == dynamic_type:
                     if k == 0:
                         node.attr["fillcolor"] = "plum"
-                    if k == 3 and 0x20000000 < word < 0x20040000:
+                    if k == 3 and ram_start < word < ram_end:
                         map_element_blocks.append(word)
 
                 if potential_type in function_types:
-                    if k == 2 and 0x20000000 < word < 0x20040000:
+                    if k == 2 and ram_start < word < ram_end:
                         bytecode_blocks.append(word)
 
 
@@ -338,7 +342,12 @@ def do_all_the_things(ram_filename, bin_filename, map_filename, print_block_cont
             pool_ptr = last_pool
             if not is_qstr(qstr_index):
                 return "object"
+
+            pool = block_data[pool_ptr]
+            prev, total_prev_len, alloc, length = struct.unpack_from("<IIII", pool)
             qstr_index >>= 3
+            if qstr_index > total_prev_len + alloc:
+                return "invalid"
             while pool_ptr != 0:
                 if pool_ptr > ram_start:
                     if pool_ptr in block_data:
@@ -492,7 +501,10 @@ def do_all_the_things(ram_filename, bin_filename, map_filename, print_block_cont
                     offset = len(data)
                     continue
                 offset += 2 + qstr_len + 1
-                qstrs_in_chunk += "  " + data[offset - qstr_len - 1: offset - 1].decode("utf-8")
+                try:
+                    qstrs_in_chunk += "  " + data[offset - qstr_len - 1: offset - 1].decode("utf-8")
+                except UnicodeDecodeError:
+                    qstrs_in_chunk += "  " + "░"*qstr_len
             printable_qstrs = ""
             for i in range(len(qstrs_in_chunk)):
                 c = qstrs_in_chunk[i]
@@ -515,20 +527,28 @@ def do_all_the_things(ram_filename, bin_filename, map_filename, print_block_cont
         # First render the graph of objects on the heap.
         if draw_heap_ownership:
             ownership_graph.layout(prog="dot")
-            fn = os.path.join(output_directory, "heap_ownership{:04d}.png".format(snapshot_num))
+            fn = os.path.join(output_directory, "heap_ownership{:04d}.svg".format(snapshot_num))
             print(fn)
             ownership_graph.draw(fn)
 
+        # Clear edge positioning from ownership graph layout.
+        if draw_heap_ownership:
+            for edge in ownership_graph.iteredges():
+                del edge.attr["pos"]
+        else:
+            for edge in ownership_graph.edges():
+                ownership_graph.delete_edge(edge)
+
         # Second, render the heap layout in memory order.
-        for node in ownership_graph:
+        for node in ownership_graph.nodes():
             try:
                 address = int(node.name)
             except ValueError:
-                ownership_graph.remove_node(node)
+                ownership_graph.remove_node(node.name)
                 continue
             block = (address - pool_start) // 16
-            x = block // 64
-            y = 64 - block % 64
+            x = block // 128
+            y = 128 - block % 128
             try:
                 height = float(node.attr["height"])
             except:
@@ -538,11 +558,6 @@ def do_all_the_things(ram_filename, bin_filename, map_filename, print_block_cont
             #    print(hex(address), block, len(block_data[address]), x, y, height)
             node.attr["pos"] = "{},{}".format(x * 80, (y - (height - 0.25) * 2) * 18) # in inches
 
-        # Clear edge positioning from ownership graph layout.
-        if draw_heap_ownership:
-            for edge in ownership_graph.iteredges():
-                del edge.attr["pos"]
-
         # Reformat block nodes so they are the correct size and do not have keys in them.
         for block in sorted(map_element_blocks):
             try:
@@ -565,9 +580,9 @@ def do_all_the_things(ram_filename, bin_filename, map_filename, print_block_cont
                 else:
                     #print("  {}, {}".format(format(key), format(value)))
                     cells.append((key, ""))
-                    if value in block_data:
-                        edge = ownership_graph.get_edge(block, value)
-                        edge.attr["tailport"] = str(key)
+                    # if value in block_data:
+                    #     edge = ownership_graph.get_edge(block, value)
+                    #     edge.attr["tailport"] = str(key)
             rows = ""
             for i in range(len(cells) // 2):
                 rows += "<tr><td port=\"{}\" height=\"18\" width=\"40\">{}</td><td port=\"{}\" height=\"18\" width=\"40\">{}</td></tr>".format(
@@ -586,6 +601,7 @@ def do_all_the_things(ram_filename, bin_filename, map_filename, print_block_cont
         if draw_heap_layout:
             fn = os.path.join(output_directory, "heap_layout{:04d}.png".format(snapshot_num))
             print(fn)
+            #ownership_graph.write(fn+".dot")
             ownership_graph.draw(fn)
 
 if __name__ == "__main__":
diff --git a/tools/output_gc_until_repl.txt b/tools/output_gc_until_repl.txt
index 0e9962635..81711deeb 100644
--- a/tools/output_gc_until_repl.txt
+++ b/tools/output_gc_until_repl.txt
@@ -19,7 +19,7 @@ append binary memory ram.bin &_srelocate &_estack
 continue
 end
 
-break main.c:164
+break main.c:179
 
 continue