Merge remote-tracking branch 'upstream/master' into stm32-meowbit

27 files changed, 1547 insertions, 279 deletions

diff --git a/conf.py b/conf.py
index abee78aba..3b29986c0 100644
--- a/conf.py
+++ b/conf.py
@@ -125,6 +125,7 @@ exclude_patterns = ["**/build*",
                     "ports/cc3200",
                     "ports/cc3200/FreeRTOS",
                     "ports/cc3200/hal",
+                    "ports/cxd56/mkspk",
                     "ports/cxd56/spresense-exported-sdk",
                     "ports/esp32",
                     "ports/esp8266/boards",
diff --git a/ports/atmel-samd/boards/feather_m4_express/pins.c b/ports/atmel-samd/boards/feather_m4_express/pins.c
index d9496ecfc..61bd8abad 100644
--- a/ports/atmel-samd/boards/feather_m4_express/pins.c
+++ b/ports/atmel-samd/boards/feather_m4_express/pins.c
@@ -2,18 +2,38 @@
 
 STATIC const mp_rom_map_elem_t board_global_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_A0), MP_ROM_PTR(&pin_PA02) },
+    { MP_ROM_QSTR(MP_QSTR_D14), MP_ROM_PTR(&pin_PA02) },
+
     { MP_ROM_QSTR(MP_QSTR_A1), MP_ROM_PTR(&pin_PA05) },
+    { MP_ROM_QSTR(MP_QSTR_D15), MP_ROM_PTR(&pin_PA05) },
+
     { MP_ROM_QSTR(MP_QSTR_A2), MP_ROM_PTR(&pin_PB08) },
+    { MP_ROM_QSTR(MP_QSTR_D16), MP_ROM_PTR(&pin_PB08) },
+
     { MP_ROM_QSTR(MP_QSTR_A3), MP_ROM_PTR(&pin_PB09) },
+    { MP_ROM_QSTR(MP_QSTR_D17), MP_ROM_PTR(&pin_PB09) },
+
     { MP_ROM_QSTR(MP_QSTR_A4), MP_ROM_PTR(&pin_PA04) },
+    { MP_ROM_QSTR(MP_QSTR_D18), MP_ROM_PTR(&pin_PA04) },
+
     { MP_ROM_QSTR(MP_QSTR_A5), MP_ROM_PTR(&pin_PA06) },
+    { MP_ROM_QSTR(MP_QSTR_D19), MP_ROM_PTR(&pin_PA06) },
+
     { MP_ROM_QSTR(MP_QSTR_SCK), MP_ROM_PTR(&pin_PA17) },
+    { MP_ROM_QSTR(MP_QSTR_D25), MP_ROM_PTR(&pin_PA17) },
+
     { MP_ROM_QSTR(MP_QSTR_MOSI), MP_ROM_PTR(&pin_PB23) },
+    { MP_ROM_QSTR(MP_QSTR_D24), MP_ROM_PTR(&pin_PB23) },
+
     { MP_ROM_QSTR(MP_QSTR_MISO), MP_ROM_PTR(&pin_PB22) },
+    { MP_ROM_QSTR(MP_QSTR_D23), MP_ROM_PTR(&pin_PB22) },
+
     { MP_ROM_QSTR(MP_QSTR_D0), MP_ROM_PTR(&pin_PB17) },
     { MP_ROM_QSTR(MP_QSTR_RX), MP_ROM_PTR(&pin_PB17) },
+
     { MP_ROM_QSTR(MP_QSTR_D1), MP_ROM_PTR(&pin_PB16) },
     { MP_ROM_QSTR(MP_QSTR_TX), MP_ROM_PTR(&pin_PB16) },
+
     { MP_ROM_QSTR(MP_QSTR_SDA), MP_ROM_PTR(&pin_PA12) },
     { MP_ROM_QSTR(MP_QSTR_SCL), MP_ROM_PTR(&pin_PA13) },
     { MP_ROM_QSTR(MP_QSTR_D4), MP_ROM_PTR(&pin_PA14) },
@@ -24,9 +44,12 @@ STATIC const mp_rom_map_elem_t board_global_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_D11), MP_ROM_PTR(&pin_PA21) },
     { MP_ROM_QSTR(MP_QSTR_D12), MP_ROM_PTR(&pin_PA22) },
     { MP_ROM_QSTR(MP_QSTR_D13), MP_ROM_PTR(&pin_PA23) },
+
     { MP_ROM_QSTR(MP_QSTR_NEOPIXEL), MP_ROM_PTR(&pin_PB03) },
+
     { MP_ROM_QSTR(MP_QSTR_VOLTAGE_MONITOR), MP_ROM_PTR(&pin_PB01) },
     { MP_ROM_QSTR(MP_QSTR_BATTERY), MP_ROM_PTR(&pin_PB01) },
+
     { MP_ROM_QSTR(MP_QSTR_I2C), MP_ROM_PTR(&board_i2c_obj) },
     { MP_ROM_QSTR(MP_QSTR_SPI), MP_ROM_PTR(&board_spi_obj) },
     { MP_ROM_QSTR(MP_QSTR_UART), MP_ROM_PTR(&board_uart_obj) },
diff --git a/ports/atmel-samd/common-hal/busio/I2C.c b/ports/atmel-samd/common-hal/busio/I2C.c
index b0e5714a7..ffe74a274 100644
--- a/ports/atmel-samd/common-hal/busio/I2C.c
+++ b/ports/atmel-samd/common-hal/busio/I2C.c
@@ -76,6 +76,7 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
         mp_raise_ValueError(translate("Invalid pins"));
     }
 
+#if CIRCUITPY_REQUIRE_I2C_PULLUPS
     // Test that the pins are in a high state. (Hopefully indicating they are pulled up.)
     gpio_set_pin_function(sda->number, GPIO_PIN_FUNCTION_OFF);
     gpio_set_pin_function(scl->number, GPIO_PIN_FUNCTION_OFF);
@@ -98,6 +99,8 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
         reset_pin_number(scl->number);
         mp_raise_RuntimeError(translate("SDA or SCL needs a pull up"));
     }
+#endif
+
     gpio_set_pin_function(sda->number, sda_pinmux);
     gpio_set_pin_function(scl->number, scl_pinmux);
 
diff --git a/ports/cxd56/Makefile b/ports/cxd56/Makefile
index d65c2e266..a0782c4e9 100644
--- a/ports/cxd56/Makefile
+++ b/ports/cxd56/Makefile
@@ -67,13 +67,13 @@ PLATFORM := $(firstword $(subst _, ,$(shell uname -s 2>/dev/null)))
 
 ifeq ($(PLATFORM),Darwin)
   # macOS
-  MKSPK = $(SPRESENSE_SDK)/sdk/tools/macos/mkspk
+  MKSPK = mkspk/mkspk
 else ifeq ($(PLATFORM),Linux)
   # Linux
-  MKSPK = $(SPRESENSE_SDK)/sdk/tools/linux/mkspk
+  MKSPK = mkspk/mkspk
 else
   # Cygwin/MSYS2
-  MKSPK = $(SPRESENSE_SDK)/sdk/tools/windows/mkspk.exe
+  MKSPK = mkspk/mkspk.exe
 endif
 
 SERIAL ?= /dev/ttyUSB0
@@ -131,6 +131,7 @@ LDFLAGS = \
 	-o $(BUILD)/firmware.elf \
 	--start-group \
 	-u spresense_main \
+	-u board_timerhook \
 	$(BUILD)/libmpy.a \
 	$(SPRESENSE_SDK)/sdk/libs/libapps.a \
 	$(SPRESENSE_SDK)/sdk/libs/libsdk.a \
@@ -200,7 +201,10 @@ $(BUILD)/firmware.elf: $(BUILD)/libmpy.a
 	$(ECHO) "LD $@"
 	$(Q)$(LD) $(LDFLAGS)
 
-$(BUILD)/firmware.spk: $(BUILD)/firmware.elf
+$(MKSPK):
+	$(MAKE) -C mkspk
+
+$(BUILD)/firmware.spk: $(BUILD)/firmware.elf $(MKSPK)
 	$(ECHO) "Creating $@"
 	$(MKSPK) -c 2 $(BUILD)/firmware.elf nuttx $(BUILD)/firmware.spk
 
diff --git a/ports/cxd56/mkspk/.gitignore b/ports/cxd56/mkspk/.gitignore
new file mode 100644
index 000000000..e9a6ab18f
--- /dev/null
+++ b/ports/cxd56/mkspk/.gitignore
@@ -0,0 +1,3 @@
+/mkspk
+/mkspk.exe
+
diff --git a/ports/cxd56/mkspk/Makefile b/ports/cxd56/mkspk/Makefile
new file mode 100644
index 000000000..d91d17a3c
--- /dev/null
+++ b/ports/cxd56/mkspk/Makefile
@@ -0,0 +1,51 @@
+############################################################################
+# tools/mkspk/Makefile
+#
+#   Copyright (C) 2011-2012 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <gnutt@nuttx.org>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name NuttX nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+
+all: mkspk
+default: mkspk
+.PHONY: clean
+
+# Add CFLAGS=-g on the make command line to build debug versions
+
+CFLAGS = -O2 -Wall -I.
+
+# mkspk - Convert nuttx.hex image to nuttx.spk image
+
+mkspk:
+	@gcc $(CFLAGS) -o mkspk mkspk.c clefia.c
+
+clean:
+	@rm -f *.o *.a *.dSYM *~ .*.swp
+	@rm -f mkspk mkspk.exe
diff --git a/ports/cxd56/mkspk/clefia.c b/ports/cxd56/mkspk/clefia.c
new file mode 100644
index 000000000..02a175505
--- /dev/null
+++ b/ports/cxd56/mkspk/clefia.c
@@ -0,0 +1,517 @@
+/****************************************************************************
+ * tools/cxd56/clefia.c
+ *
+ * Copyright (C) 2007, 2008 Sony Corporation
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <assert.h>
+
+#include "clefia.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define clefiamul4(_x) (clefiamul2(clefiamul2((_x))))
+#define clefiamul6(_x) (clefiamul2((_x)) ^ clefiamul4((_x)))
+#define clefiamul8(_x) (clefiamul2(clefiamul4((_x))))
+#define clefiamula(_x) (clefiamul2((_x)) ^ clefiamul8((_x)))
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/* S0 (8-bit S-box based on four 4-bit S-boxes) */
+
+static const unsigned char clefia_s0[256] =
+{
+  0x57u, 0x49u, 0xd1u, 0xc6u, 0x2fu, 0x33u, 0x74u, 0xfbu,
+  0x95u, 0x6du, 0x82u, 0xeau, 0x0eu, 0xb0u, 0xa8u, 0x1cu,
+  0x28u, 0xd0u, 0x4bu, 0x92u, 0x5cu, 0xeeu, 0x85u, 0xb1u,
+  0xc4u, 0x0au, 0x76u, 0x3du, 0x63u, 0xf9u, 0x17u, 0xafu,
+  0xbfu, 0xa1u, 0x19u, 0x65u, 0xf7u, 0x7au, 0x32u, 0x20u,
+  0x06u, 0xceu, 0xe4u, 0x83u, 0x9du, 0x5bu, 0x4cu, 0xd8u,
+  0x42u, 0x5du, 0x2eu, 0xe8u, 0xd4u, 0x9bu, 0x0fu, 0x13u,
+  0x3cu, 0x89u, 0x67u, 0xc0u, 0x71u, 0xaau, 0xb6u, 0xf5u,
+  0xa4u, 0xbeu, 0xfdu, 0x8cu, 0x12u, 0x00u, 0x97u, 0xdau,
+  0x78u, 0xe1u, 0xcfu, 0x6bu, 0x39u, 0x43u, 0x55u, 0x26u,
+  0x30u, 0x98u, 0xccu, 0xddu, 0xebu, 0x54u, 0xb3u, 0x8fu,
+  0x4eu, 0x16u, 0xfau, 0x22u, 0xa5u, 0x77u, 0x09u, 0x61u,
+  0xd6u, 0x2au, 0x53u, 0x37u, 0x45u, 0xc1u, 0x6cu, 0xaeu,
+  0xefu, 0x70u, 0x08u, 0x99u, 0x8bu, 0x1du, 0xf2u, 0xb4u,
+  0xe9u, 0xc7u, 0x9fu, 0x4au, 0x31u, 0x25u, 0xfeu, 0x7cu,
+  0xd3u, 0xa2u, 0xbdu, 0x56u, 0x14u, 0x88u, 0x60u, 0x0bu,
+  0xcdu, 0xe2u, 0x34u, 0x50u, 0x9eu, 0xdcu, 0x11u, 0x05u,
+  0x2bu, 0xb7u, 0xa9u, 0x48u, 0xffu, 0x66u, 0x8au, 0x73u,
+  0x03u, 0x75u, 0x86u, 0xf1u, 0x6au, 0xa7u, 0x40u, 0xc2u,
+  0xb9u, 0x2cu, 0xdbu, 0x1fu, 0x58u, 0x94u, 0x3eu, 0xedu,
+  0xfcu, 0x1bu, 0xa0u, 0x04u, 0xb8u, 0x8du, 0xe6u, 0x59u,
+  0x62u, 0x93u, 0x35u, 0x7eu, 0xcau, 0x21u, 0xdfu, 0x47u,
+  0x15u, 0xf3u, 0xbau, 0x7fu, 0xa6u, 0x69u, 0xc8u, 0x4du,
+  0x87u, 0x3bu, 0x9cu, 0x01u, 0xe0u, 0xdeu, 0x24u, 0x52u,
+  0x7bu, 0x0cu, 0x68u, 0x1eu, 0x80u, 0xb2u, 0x5au, 0xe7u,
+  0xadu, 0xd5u, 0x23u, 0xf4u, 0x46u, 0x3fu, 0x91u, 0xc9u,
+  0x6eu, 0x84u, 0x72u, 0xbbu, 0x0du, 0x18u, 0xd9u, 0x96u,
+  0xf0u, 0x5fu, 0x41u, 0xacu, 0x27u, 0xc5u, 0xe3u, 0x3au,
+  0x81u, 0x6fu, 0x07u, 0xa3u, 0x79u, 0xf6u, 0x2du, 0x38u,
+  0x1au, 0x44u, 0x5eu, 0xb5u, 0xd2u, 0xecu, 0xcbu, 0x90u,
+  0x9au, 0x36u, 0xe5u, 0x29u, 0xc3u, 0x4fu, 0xabu, 0x64u,
+  0x51u, 0xf8u, 0x10u, 0xd7u, 0xbcu, 0x02u, 0x7du, 0x8eu
+};
+
+/* S1 (8-bit S-box based on inverse function) */
+
+static const unsigned char clefia_s1[256] =
+{
+  0x6cu, 0xdau, 0xc3u, 0xe9u, 0x4eu, 0x9du, 0x0au, 0x3du,
+  0xb8u, 0x36u, 0xb4u, 0x38u, 0x13u, 0x34u, 0x0cu, 0xd9u,
+  0xbfu, 0x74u, 0x94u, 0x8fu, 0xb7u, 0x9cu, 0xe5u, 0xdcu,
+  0x9eu, 0x07u, 0x49u, 0x4fu, 0x98u, 0x2cu, 0xb0u, 0x93u,
+  0x12u, 0xebu, 0xcdu, 0xb3u, 0x92u, 0xe7u, 0x41u, 0x60u,
+  0xe3u, 0x21u, 0x27u, 0x3bu, 0xe6u, 0x19u, 0xd2u, 0x0eu,
+  0x91u, 0x11u, 0xc7u, 0x3fu, 0x2au, 0x8eu, 0xa1u, 0xbcu,
+  0x2bu, 0xc8u, 0xc5u, 0x0fu, 0x5bu, 0xf3u, 0x87u, 0x8bu,
+  0xfbu, 0xf5u, 0xdeu, 0x20u, 0xc6u, 0xa7u, 0x84u, 0xceu,
+  0xd8u, 0x65u, 0x51u, 0xc9u, 0xa4u, 0xefu, 0x43u, 0x53u,
+  0x25u, 0x5du, 0x9bu, 0x31u, 0xe8u, 0x3eu, 0x0du, 0xd7u,
+  0x80u, 0xffu, 0x69u, 0x8au, 0xbau, 0x0bu, 0x73u, 0x5cu,
+  0x6eu, 0x54u, 0x15u, 0x62u, 0xf6u, 0x35u, 0x30u, 0x52u,
+  0xa3u, 0x16u, 0xd3u, 0x28u, 0x32u, 0xfau, 0xaau, 0x5eu,
+  0xcfu, 0xeau, 0xedu, 0x78u, 0x33u, 0x58u, 0x09u, 0x7bu,
+  0x63u, 0xc0u, 0xc1u, 0x46u, 0x1eu, 0xdfu, 0xa9u, 0x99u,
+  0x55u, 0x04u, 0xc4u, 0x86u, 0x39u, 0x77u, 0x82u, 0xecu,
+  0x40u, 0x18u, 0x90u, 0x97u, 0x59u, 0xddu, 0x83u, 0x1fu,
+  0x9au, 0x37u, 0x06u, 0x24u, 0x64u, 0x7cu, 0xa5u, 0x56u,
+  0x48u, 0x08u, 0x85u, 0xd0u, 0x61u, 0x26u, 0xcau, 0x6fu,
+  0x7eu, 0x6au, 0xb6u, 0x71u, 0xa0u, 0x70u, 0x05u, 0xd1u,
+  0x45u, 0x8cu, 0x23u, 0x1cu, 0xf0u, 0xeeu, 0x89u, 0xadu,
+  0x7au, 0x4bu, 0xc2u, 0x2fu, 0xdbu, 0x5au, 0x4du, 0x76u,
+  0x67u, 0x17u, 0x2du, 0xf4u, 0xcbu, 0xb1u, 0x4au, 0xa8u,
+  0xb5u, 0x22u, 0x47u, 0x3au, 0xd5u, 0x10u, 0x4cu, 0x72u,
+  0xccu, 0x00u, 0xf9u, 0xe0u, 0xfdu, 0xe2u, 0xfeu, 0xaeu,
+  0xf8u, 0x5fu, 0xabu, 0xf1u, 0x1bu, 0x42u, 0x81u, 0xd6u,
+  0xbeu, 0x44u, 0x29u, 0xa6u, 0x57u, 0xb9u, 0xafu, 0xf2u,
+  0xd4u, 0x75u, 0x66u, 0xbbu, 0x68u, 0x9fu, 0x50u, 0x02u,
+  0x01u, 0x3cu, 0x7fu, 0x8du, 0x1au, 0x88u, 0xbdu, 0xacu,
+  0xf7u, 0xe4u, 0x79u, 0x96u, 0xa2u, 0xfcu, 0x6du, 0xb2u,
+  0x6bu, 0x03u, 0xe1u, 0x2eu, 0x7du, 0x14u, 0x95u, 0x1du
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static void bytecpy(unsigned char *dst, const unsigned char *src, int bytelen)
+{
+  while (bytelen-- > 0)
+    {
+      *dst++ = *src++;
+    }
+}
+
+static unsigned char clefiamul2(unsigned char x)
+{
+  /* multiplication over GF(2^8) (p(x) = '11d') */
+
+  if (x & 0x80u)
+    {
+      x ^= 0x0eu;
+    }
+
+  return ((x << 1) | (x >> 7));
+}
+
+static void clefiaf0xor(unsigned char *dst, const unsigned char *src,
+                        const unsigned char *rk)
+{
+  unsigned char x[4];
+  unsigned char y[4];
+  unsigned char z[4];
+
+  /* F0 */
+
+  /* Key addition */
+
+  bytexor(x, src, rk, 4);
+
+  /* Substitution layer */
+
+  z[0] = clefia_s0[x[0]];
+  z[1] = clefia_s1[x[1]];
+  z[2] = clefia_s0[x[2]];
+  z[3] = clefia_s1[x[3]];
+
+  /* Diffusion layer (M0) */
+
+  y[0] = z[0] ^ clefiamul2(z[1]) ^ clefiamul4(z[2]) ^ clefiamul6(z[3]);
+  y[1] = clefiamul2(z[0]) ^ z[1] ^ clefiamul6(z[2]) ^ clefiamul4(z[3]);
+  y[2] = clefiamul4(z[0]) ^ clefiamul6(z[1]) ^ z[2] ^ clefiamul2(z[3]);
+  y[3] = clefiamul6(z[0]) ^ clefiamul4(z[1]) ^ clefiamul2(z[2]) ^ z[3];
+
+  /* Xoring after F0 */
+
+  bytecpy(dst + 0, src + 0, 4);
+  bytexor(dst + 4, src + 4, y, 4);
+}
+
+static void clefiaf1xor(unsigned char *dst, const unsigned char *src,
+                        const unsigned char *rk)
+{
+  unsigned char x[4];
+  unsigned char y[4];
+  unsigned char z[4];
+
+  /* F1 */
+
+  /* Key addition */
+
+  bytexor(x, src, rk, 4);
+
+  /* Substitution layer */
+
+  z[0] = clefia_s1[x[0]];
+  z[1] = clefia_s0[x[1]];
+  z[2] = clefia_s1[x[2]];
+  z[3] = clefia_s0[x[3]];
+
+  /* Diffusion layer (M1) */
+
+  y[0] = z[0] ^ clefiamul8(z[1]) ^ clefiamul2(z[2]) ^ clefiamula(z[3]);
+  y[1] = clefiamul8(z[0]) ^ z[1] ^ clefiamula(z[2]) ^ clefiamul2(z[3]);
+  y[2] = clefiamul2(z[0]) ^ clefiamula(z[1]) ^ z[2] ^ clefiamul8(z[3]);
+  y[3] = clefiamula(z[0]) ^ clefiamul2(z[1]) ^ clefiamul8(z[2]) ^ z[3];
+
+  /* Xoring after F1 */
+
+  bytecpy(dst + 0, src + 0, 4);
+  bytexor(dst + 4, src + 4, y, 4);
+}
+
+static void clefiagfn4(unsigned char *y, const unsigned char *x,
+                       const unsigned char *rk, int r)
+{
+  unsigned char fin[16];
+  unsigned char fout[16];
+
+  bytecpy(fin, x, 16);
+  while (r-- > 0)
+    {
+      clefiaf0xor(fout + 0, fin + 0, rk + 0);
+      clefiaf1xor(fout + 8, fin + 8, rk + 4);
+      rk += 8;
+      if (r)
+        {
+          /* swapping for encryption */
+
+          bytecpy(fin + 0, fout + 4, 12);
+          bytecpy(fin + 12, fout + 0, 4);
+        }
+    }
+
+  bytecpy(y, fout, 16);
+}
+
+#if 0 /* Not used */
+static void clefiagfn8(unsigned char *y, const unsigned char *x,
+                       const unsigned char *rk, int r)
+{
+  unsigned char fin[32];
+  unsigned char fout[32];
+
+  bytecpy(fin, x, 32);
+  while (r-- > 0)
+    {
+      clefiaf0xor(fout + 0, fin + 0, rk + 0);
+      clefiaf1xor(fout + 8, fin + 8, rk + 4);
+      clefiaf0xor(fout + 16, fin + 16, rk + 8);
+      clefiaf1xor(fout + 24, fin + 24, rk + 12);
+      rk += 16;
+      if (r)
+        {
+          /* swapping for encryption */
+
+          bytecpy(fin + 0, fout + 4, 28);
+          bytecpy(fin + 28, fout + 0, 4);
+        }
+    }
+
+  bytecpy(y, fout, 32);
+}
+#endif
+
+#if 0 /* Not used */
+static void clefiagfn4inv(unsigned char *y, const unsigned char *x,
+                          const unsigned char *rk, int r)
+{
+  unsigned char fin[16];
+  unsigned char fout[16];
+
+  rk += (r - 1) * 8;
+  bytecpy(fin, x, 16);
+  while (r-- > 0)
+    {
+      clefiaf0xor(fout + 0, fin + 0, rk + 0);
+      clefiaf1xor(fout + 8, fin + 8, rk + 4);
+      rk -= 8;
+      if (r)
+        {
+          /* swapping for decryption */
+
+          bytecpy(fin + 0, fout + 12, 4);
+          bytecpy(fin + 4, fout + 0, 12);
+        }
+    }
+
+  bytecpy(y, fout, 16);
+}
+#endif
+
+static void clefiadoubleswap(unsigned char *lk)
+{
+  unsigned char t[16];
+
+  t[0] = (lk[0] << 7) | (lk[1] >> 1);
+  t[1] = (lk[1] << 7) | (lk[2] >> 1);
+  t[2] = (lk[2] << 7) | (lk[3] >> 1);
+  t[3] = (lk[3] << 7) | (lk[4] >> 1);
+  t[4] = (lk[4] << 7) | (lk[5] >> 1);
+  t[5] = (lk[5] << 7) | (lk[6] >> 1);
+  t[6] = (lk[6] << 7) | (lk[7] >> 1);
+  t[7] = (lk[7] << 7) | (lk[15] & 0x7fu);
+
+  t[8] = (lk[8] >> 7) | (lk[0] & 0xfeu);
+  t[9] = (lk[9] >> 7) | (lk[8] << 1);
+  t[10] = (lk[10] >> 7) | (lk[9] << 1);
+  t[11] = (lk[11] >> 7) | (lk[10] << 1);
+  t[12] = (lk[12] >> 7) | (lk[11] << 1);
+  t[13] = (lk[13] >> 7) | (lk[12] << 1);
+  t[14] = (lk[14] >> 7) | (lk[13] << 1);
+  t[15] = (lk[15] >> 7) | (lk[14] << 1);
+
+  bytecpy(lk, t, 16);
+}
+
+static void clefiaconset(unsigned char *con, const unsigned char *iv, int lk)
+{
+  unsigned char t[2];
+  unsigned char tmp;
+
+  bytecpy(t, iv, 2);
+  while (lk-- > 0)
+    {
+      con[0] = t[0] ^ 0xb7u;    /* P_16 = 0xb7e1 (natural logarithm) */
+      con[1] = t[1] ^ 0xe1u;
+      con[2] = ~((t[0] << 1) | (t[1] >> 7));
+      con[3] = ~((t[1] << 1) | (t[0] >> 7));
+      con[4] = ~t[0] ^ 0x24u;   /* Q_16 = 0x243f (circle ratio) */
+      con[5] = ~t[1] ^ 0x3fu;
+      con[6] = t[1];
+      con[7] = t[0];
+      con += 8;
+
+      /* updating T */
+
+      if (t[1] & 0x01u)
+        {
+          t[0] ^= 0xa8u;
+          t[1] ^= 0x30u;
+        }
+
+      tmp = t[0] << 7;
+      t[0] = (t[0] >> 1) | (t[1] << 7);
+      t[1] = (t[1] >> 1) | tmp;
+    }
+}
+
+static void left_shift_one(uint8_t * in, uint8_t * out)
+{
+  int i;
+  int overflow;
+
+  overflow = 0;
+  for (i = 15; i >= 0; i--)
+    {
+      out[i] = in[i] << 1;
+      out[i] |= overflow;
+      overflow = (in[i] >> 7) & 1;
+    }
+}
+
+static void gen_subkey(struct cipher *c)
+{
+  uint8_t L[16];
+
+  memset(L, 0, 16);
+  clefiaencrypt(L, L, c->rk, c->round);
+
+  left_shift_one(L, c->k1);
+  if (L[0] & 0x80)
+    {
+      c->k1[15] = c->k1[15] ^ 0x87;
+    }
+
+  left_shift_one(c->k1, c->k2);
+  if (c->k1[0] & 0x80)
+    {
+      c->k2[15] = c->k2[15] ^ 0x87;
+    }
+
+  memset(L, 0, 16);
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+struct cipher *cipher_init(uint8_t * key, uint8_t * iv)
+{
+  struct cipher *c;
+
+  c = (struct cipher *)malloc(sizeof(*c));
+  if (!c)
+    {
+      return NULL;
+    }
+
+  c->round = clefiakeyset(c->rk, key);
+
+  gen_subkey(c);
+  memset(c->vector, 0, 16);
+
+  return c;
+}
+
+void cipher_deinit(struct cipher *c)
+{
+  memset(c, 0, sizeof(*c));
+  free(c);
+}
+
+int cipher_calc_cmac(struct cipher *c, void *data, int size, void *cmac)
+{
+  uint8_t m[16];
+  uint8_t *p;
+
+  if (size & 0xf)
+    {
+      return -1;
+    }
+
+  p = (uint8_t *) data;
+  while (size)
+    {
+      bytexor(m, c->vector, p, 16);
+      clefiaencrypt(c->vector, m, c->rk, c->round);
+      size -= 16;
+      p += 16;
+    }
+
+  bytexor(cmac, m, c->k1, 16);
+  clefiaencrypt(cmac, cmac, c->rk, c->round);
+  memset(m, 0, 16);
+
+  return 0;
+}
+
+void bytexor(unsigned char *dst, const unsigned char *a,
+             const unsigned char *b, int bytelen)
+{
+  while (bytelen-- > 0)
+    {
+      *dst++ = *a++ ^ *b++;
+    }
+}
+
+int clefiakeyset(unsigned char *rk, const unsigned char *skey)
+{
+  const unsigned char iv[2] =
+  {
+    0x42u, 0x8au  /* cubic root of 2 */
+  };
+
+  unsigned char lk[16];
+  unsigned char con128[4 * 60];
+  int i;
+
+  /* generating CONi^(128) (0 <= i < 60, lk = 30) */
+
+  clefiaconset(con128, iv, 30);
+
+  /* GFN_{4,12} (generating L from K) */
+
+  clefiagfn4(lk, skey, con128, 12);
+
+  bytecpy(rk, skey, 8);    /* initial whitening key (WK0, WK1) */
+  rk += 8;
+  for (i = 0; i < 9; i++)
+    {
+      /* round key (RKi (0 <= i < 36)) */
+
+      bytexor(rk, lk, con128 + i * 16 + (4 * 24), 16);
+      if (i % 2)
+        {
+          bytexor(rk, rk, skey, 16);    /* Xoring K */
+        }
+
+      clefiadoubleswap(lk);     /* Updating L (DoubleSwap function) */
+      rk += 16;
+    }
+
+  bytecpy(rk, skey + 8, 8);     /* final whitening key (WK2, WK3) */
+
+  return 18;
+}
+
+void clefiaencrypt(unsigned char *ct, const unsigned char *pt,
+                   const unsigned char *rk, const int r)
+{
+  unsigned char rin[16];
+  unsigned char  rout[16];
+
+  bytecpy(rin, pt, 16);
+
+  bytexor(rin + 4, rin + 4, rk + 0, 4); /* initial key whitening */
+  bytexor(rin + 12, rin + 12, rk + 4, 4);
+  rk += 8;
+
+  clefiagfn4(rout, rin, rk, r); /* GFN_{4,r} */
+
+  bytecpy(ct, rout, 16);
+  bytexor(ct + 4, ct + 4, rk + r * 8 + 0, 4);   /* final key whitening */
+  bytexor(ct + 12, ct + 12, rk + r * 8 + 4, 4);
+}
diff --git a/ports/cxd56/mkspk/clefia.h b/ports/cxd56/mkspk/clefia.h
new file mode 100644
index 000000000..a0e02587d
--- /dev/null
+++ b/ports/cxd56/mkspk/clefia.h
@@ -0,0 +1,65 @@
+/****************************************************************************
+ * tools/cxd56/clefia.h
+ *
+ * Copyright (C) 2007, 2008 Sony Corporation
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *****************************************************************************/
+
+#ifndef _TOOLS_CXD56_CLEFIA_H_
+#define _TOOLS_CXD56_CLEFIA_H_
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+struct cipher
+  {
+    int mode;
+    int dir;
+    uint8_t rk[8 * 26 + 16];
+    uint8_t vector[16];
+    int round;
+    uint8_t k1[16];
+    uint8_t k2[16];
+  };
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+struct cipher *cipher_init(uint8_t * key, uint8_t * iv);
+void cipher_deinit(struct cipher *c);
+int cipher_calc_cmac(struct cipher *c, void *data, int size, void *cmac);
+void bytexor(unsigned char *dst, const unsigned char *a,
+             const unsigned char *b, int bytelen);
+int clefiakeyset(unsigned char *rk, const unsigned char *skey);
+void clefiaencrypt(unsigned char *ct, const unsigned char *pt,
+                   const unsigned char *rk, const int r);
+
+#endif
diff --git a/ports/cxd56/mkspk/mkspk.c b/ports/cxd56/mkspk/mkspk.c
new file mode 100644
index 000000000..c447ad7da
--- /dev/null
+++ b/ports/cxd56/mkspk/mkspk.c
@@ -0,0 +1,383 @@
+/****************************************************************************
+ * tools/cxd56/mkspk.c
+ *
+ * Copyright (C) 2007, 2008 Sony Corporation
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <assert.h>
+
+#include "mkspk.h"
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+struct args
+{
+  int core;
+  char *elffile;
+  char *savename;
+  char *outputfile;
+};
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static uint8_t vmk[16] =
+  "\x27\xc0\xaf\x1b\x5d\xcb\xc6\xc5\x58\x22\x1c\xdd\xaf\xf3\x20\x21";
+
+static struct args g_options =
+{
+  0
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static struct args *parse_args(int argc, char **argv)
+{
+  int opt;
+  int show_help;
+  struct args *args = &g_options;
+  char *endp;
+
+  show_help = 0;
+
+  if (argc < 2)
+    {
+      show_help = 1;
+    }
+
+  memset(args, 0, sizeof(*args));
+  args->core = -1;
+
+  while ((opt = getopt(argc, argv, "h:c:")) != -1)
+    {
+      switch (opt)
+        {
+        case 'c':
+          args->core = strtol(optarg, &endp, 0);
+          if (*endp)
+            {
+              fprintf(stderr, "Invalid core number \"%s\"\n", optarg);
+              show_help = 1;
+            }
+          break;
+
+        case 'h':
+        default:
+          show_help = 1;
+        }
+    }
+
+  argc -= optind;
+  argv += optind;
+
+  args->elffile = argv[0];
+  args->savename = argv[1];
+  argc -= 2;
+  argv += 2;
+
+  if (argc > 0)
+    {
+      args->outputfile = strdup(argv[0]);
+    }
+  else
+    {
+      show_help = 1;
+    }
+
+  /* Sanity checks for options */
+
+  if (show_help == 1)
+    {
+      fprintf(stderr,
+              "mkspk [-c <number>] <filename> <save name> [<output file>]\n");
+      exit(EXIT_FAILURE);
+    }
+
+  if (args->core < 0)
+    {
+      fprintf(stderr, "Core number is not set. Please use -c option.\n");
+      exit(EXIT_FAILURE);
+    }
+
+  if (strlen(args->savename) > 63)
+    {
+      fprintf(stderr, "savename too long.\n");
+      exit(EXIT_FAILURE);
+    }
+
+  return args;
+}
+
+static struct elf_file *load_elf(const char *filename)
+{
+  size_t fsize;
+  int pos;
+  char *buf;
+  FILE *fp;
+  struct elf_file *ef;
+  Elf32_Shdr *sh;
+  uint16_t i;
+  int ret;
+
+  fp = fopen(filename, "rb");
+  if (!fp)
+    {
+      return NULL;
+    }
+
+  ef = (struct elf_file *)malloc(sizeof(*ef));
+  if (!ef)
+    {
+      return NULL;
+    }
+
+  pos = fseek(fp, 0, SEEK_END);
+  fsize = (size_t) ftell(fp);
+  fseek(fp, pos, SEEK_SET);
+
+  buf = (char *)malloc(fsize);
+  if (!buf)
+    {
+      return NULL;
+    }
+
+  ret = fread(buf, fsize, 1, fp);
+  fclose(fp);
+  if (ret != 1)
+    {
+      return NULL;
+    }
+
+  ef->data = buf;
+
+  ef->ehdr = (Elf32_Ehdr *) buf;
+
+  Elf32_Ehdr *h = (Elf32_Ehdr *) buf;
+
+  if (!(h->e_ident[EI_MAG0] == 0x7f &&
+        h->e_ident[EI_MAG1] == 'E' &&
+        h->e_ident[EI_MAG2] == 'L' && h->e_ident[EI_MAG3] == 'F'))
+    {
+      free(ef);
+      free(buf);
+      return NULL;
+    }
+
+  ef->phdr = (Elf32_Phdr *) (buf + ef->ehdr->e_phoff);
+  ef->shdr = (Elf32_Shdr *) (buf + ef->ehdr->e_shoff);
+  ef->shstring = buf + ef->shdr[ef->ehdr->e_shstrndx].sh_offset;
+
+  for (i = 0, sh = ef->shdr; i < ef->ehdr->e_shnum; i++, sh++)
+    {
+      if (sh->sh_type == SHT_SYMTAB)
+        {
+          ef->symtab = (Elf32_Sym *) (buf + sh->sh_offset);
+          ef->nsyms = sh->sh_size / sh->sh_entsize;
+          continue;
+        }
+
+      if (sh->sh_type == SHT_STRTAB)
+        {
+          if (!strcmp(".strtab", ef->shstring + sh->sh_name))
+            {
+              ef->string = buf + sh->sh_offset;
+            }
+        }
+    }
+
+  return ef;
+}
+
+static void *create_image(struct elf_file *elf, int core, char *savename,
+                         int *image_size)
+{
+  char *img;
+  struct spk_header *header;
+  struct spk_prog_info *pi;
+  Elf32_Phdr *ph;
+  Elf32_Sym *sym;
+  char *name;
+  int snlen;
+  int nphs, psize, imgsize;
+  int i;
+  int j;
+  uint32_t offset;
+  uint32_t sp;
+
+  snlen = alignup(strlen(savename) + 1, 16);
+
+  nphs = 0;
+  psize = 0;
+  for (i = 0, ph = elf->phdr; i < elf->ehdr->e_phnum; i++, ph++)
+    {
+      if (ph->p_type != PT_LOAD || ph->p_filesz == 0)
+        {
+          continue;
+        }
+
+      nphs++;
+      psize += alignup(ph->p_filesz, 16);
+    }
+
+  imgsize = sizeof(*header) + snlen + (nphs * 16) + psize;
+
+  img = (char *)malloc(imgsize + 32);
+  if (!img)
+    {
+      return NULL;
+    }
+
+  *image_size = imgsize;
+  sym = elf->symtab;
+  name = elf->string;
+  sp = 0;
+
+  for (j = 0; j < elf->nsyms; j++, sym++)
+    {
+      if (!strcmp("__stack", name + sym->st_name))
+        {
+          sp = sym->st_value;
+        }
+    }
+
+  memset(img, 0, imgsize);
+
+  header = (struct spk_header *)img;
+  header->magic[0] = 0xef;
+  header->magic[1] = 'M';
+  header->magic[2] = 'O';
+  header->magic[3] = 'D';
+  header->cpu = core;
+
+  header->entry = elf->ehdr->e_entry;
+  header->stack = sp;
+  header->core = core;
+
+  header->binaries = nphs;
+  header->phoffs = sizeof(*header) + snlen;
+  header->mode = 0777;
+
+  strncpy(img + sizeof(*header), savename, 63);
+
+  ph = elf->phdr;
+  pi = (struct spk_prog_info *)(img + header->phoffs);
+  offset = ((char *)pi - img) + (nphs * sizeof(*pi));
+  for (i = 0; i < elf->ehdr->e_phnum; i++, ph++)
+    {
+      if (ph->p_type != PT_LOAD || ph->p_filesz == 0)
+        continue;
+      pi->load_address = ph->p_paddr;
+      pi->offset = offset;
+      pi->size = alignup(ph->p_filesz, 16);     /* need 16 bytes align for
+                                                 * decryption */
+      pi->memsize = ph->p_memsz;
+
+      memcpy(img + pi->offset, elf->data + ph->p_offset, ph->p_filesz);
+
+      offset += alignup(ph->p_filesz, 16);
+      pi++;
+    }
+
+  return img;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+int main(int argc, char **argv)
+{
+  struct args *args;
+  struct elf_file *elf;
+  struct cipher *c;
+  uint8_t *spkimage;
+  int size = 0;
+  FILE *fp;
+  char footer[16];
+
+  args = parse_args(argc, argv);
+
+  elf = load_elf(args->elffile);
+  if (!elf)
+    {
+      fprintf(stderr, "Loading ELF %s failure.\n", args->elffile);
+      exit(EXIT_FAILURE);
+    }
+
+  spkimage = create_image(elf, args->core, args->savename, &size);
+  free(elf);
+
+  c = cipher_init(vmk, NULL);
+  cipher_calc_cmac(c, spkimage, size, (uint8_t *) spkimage + size);
+  cipher_deinit(c);
+
+  size += 16;                   /* Extend CMAC size */
+
+  snprintf(footer, 16, "MKSPK_BN_HOOTER");
+  footer[15] = '\0';
+
+  fp = fopen(args->outputfile, "wb");
+  if (!fp)
+    {
+      fprintf(stderr, "Output file open error.\n");
+      free(spkimage);
+      exit(EXIT_FAILURE);
+    }
+
+  fwrite(spkimage, size, 1, fp);
+  fwrite(footer, 16, 1, fp);
+
+  fclose(fp);
+
+  printf("File %s is successfully created.\n", args->outputfile);
+  free(args->outputfile);
+
+  memset(spkimage, 0, size);
+  free(spkimage);
+
+  exit(EXIT_SUCCESS);
+}
diff --git a/ports/cxd56/mkspk/mkspk.h b/ports/cxd56/mkspk/mkspk.h
new file mode 100644
index 000000000..5a67bb3dd
--- /dev/null
+++ b/ports/cxd56/mkspk/mkspk.h
@@ -0,0 +1,83 @@
+/****************************************************************************
+ * tools/cxd56/mkspk.h
+ *
+ * Copyright (C) 2007, 2008 Sony Corporation
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include "clefia.h"
+#include "elf.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define alignup(x, a) (((x) + ((a) - 1)) & ~((a) - 1))
+#define swap(a, b) { (a) ^= (b); (b) ^= (a); (a) ^= (b); }
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+struct spk_header
+  {
+    uint8_t magic[4];
+    uint8_t cpu;
+    uint8_t reserved[11];
+    uint32_t entry;
+    uint32_t stack;
+    uint16_t core;
+    uint16_t binaries;
+    uint16_t phoffs;
+    uint16_t mode;
+  };
+
+struct spk_prog_info
+  {
+    uint32_t load_address;
+    uint32_t offset;
+    uint32_t size;
+    uint32_t memsize;
+  };
+
+struct elf_file
+  {
+    Elf32_Ehdr *ehdr;
+    Elf32_Phdr *phdr;
+    Elf32_Shdr *shdr;
+    Elf32_Sym *symtab;
+    int nsyms;
+    char *shstring;
+    char *string;
+    char *data;
+  };
diff --git a/ports/mimxrt10xx/common-hal/busio/I2C.c b/ports/mimxrt10xx/common-hal/busio/I2C.c
index 3c555df45..2de996f9a 100644
--- a/ports/mimxrt10xx/common-hal/busio/I2C.c
+++ b/ports/mimxrt10xx/common-hal/busio/I2C.c
@@ -98,11 +98,13 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
 
     LPI2C_MasterInit(self->i2c, &config, I2C_CLOCK_FREQ);
 
+#if CIRCUITPY_REQUIRE_I2C_PULLUPS
 //    if (!gpio_get_pin_level(sda->number) || !gpio_get_pin_level(scl->number)) {
 //        reset_pin_number(sda->number);
 //        reset_pin_number(scl->number);
 //        mp_raise_RuntimeError(translate("SDA or SCL needs a pull up"));
 //    }
+#endif
 
     claim_pin(self->sda_pin->pin);
     claim_pin(self->scl_pin->pin);
diff --git a/ports/nrf/common-hal/busio/I2C.c b/ports/nrf/common-hal/busio/I2C.c
index f6f686cdf..219fbf447 100644
--- a/ports/nrf/common-hal/busio/I2C.c
+++ b/ports/nrf/common-hal/busio/I2C.c
@@ -115,6 +115,7 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self, const mcu_pin_obj_t *
         mp_raise_ValueError(translate("All I2C peripherals are in use"));
     }
 
+#if CIRCUITPY_REQUIRE_I2C_PULLUPS
     // Test that the pins are in a high state. (Hopefully indicating they are pulled up.)
     nrf_gpio_cfg_input(scl->number, NRF_GPIO_PIN_PULLDOWN);
     nrf_gpio_cfg_input(sda->number, NRF_GPIO_PIN_PULLDOWN);
@@ -132,6 +133,7 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self, const mcu_pin_obj_t *
         reset_pin_number(scl->number);
         mp_raise_RuntimeError(translate("SDA or SCL needs a pull up"));
     }
+#endif
 
     nrfx_twim_config_t config = NRFX_TWIM_DEFAULT_CONFIG(scl->number, sda->number);
 
diff --git a/ports/nrf/common-hal/os/__init__.c b/ports/nrf/common-hal/os/__init__.c
index e38226f94..b2ad00a5c 100644
--- a/ports/nrf/common-hal/os/__init__.c
+++ b/ports/nrf/common-hal/os/__init__.c
@@ -66,8 +66,24 @@ bool common_hal_os_urandom(uint8_t *buffer, uint32_t length) {
     uint8_t sd_en = 0;
     (void) sd_softdevice_is_enabled(&sd_en);
 
-    if (sd_en)
-        return NRF_SUCCESS == sd_rand_application_vector_get(buffer, length);
+    if (sd_en) {
+        while (length != 0) {
+            uint8_t available = 0;
+            sd_rand_application_bytes_available_get(&available);
+            if (available) {
+                uint32_t request = MIN(length, available);
+                uint32_t result = sd_rand_application_vector_get(buffer, request);
+                if (result != NRF_SUCCESS) {
+                    return false;
+                }
+                buffer += request;
+                length -= request;
+            } else {
+                RUN_BACKGROUND_TASKS;
+            }
+        }
+        return true;
+    }
 #endif
 
     nrf_rng_event_clear(NRF_RNG, NRF_RNG_EVENT_VALRDY);
diff --git a/ports/stm32f4/common-hal/busio/I2C.c b/ports/stm32f4/common-hal/busio/I2C.c
index d2292845e..1437e5e78 100644
--- a/ports/stm32f4/common-hal/busio/I2C.c
+++ b/ports/stm32f4/common-hal/busio/I2C.c
@@ -35,51 +35,46 @@
 #include "supervisor/shared/translate.h"
 #include "common-hal/microcontroller/Pin.h"
 
-STATIC bool reserved_i2c[3];
-STATIC bool never_reset[3];
+//arrays use 0 based numbering: I2C1 is stored at index 0
+#define MAX_I2C 3
+STATIC bool reserved_i2c[MAX_I2C];
+STATIC bool never_reset_i2c[MAX_I2C];
 
-void i2c_reset(void) {
-    //Note: I2Cs are also forcibly reset in construct, due to silicon error
-    #ifdef I2C1
-        reserved_i2c[0] = false;
-        __HAL_RCC_I2C1_CLK_DISABLE(); 
-    #endif
-    #ifdef I2C2
-        reserved_i2c[1] = false;
-        __HAL_RCC_I2C2_CLK_DISABLE(); 
-    #endif
-    #ifdef I2C3
-        reserved_i2c[2] = false;
-        __HAL_RCC_I2C3_CLK_DISABLE(); 
-    #endif
-}
-
-void common_hal_busio_i2c_never_reset(busio_i2c_obj_t *self) {
-    for (size_t i = 0 ; i < MP_ARRAY_SIZE(mcu_i2c_banks); i++) {
-        if (self->handle.Instance == mcu_i2c_banks[i]) {
-            never_reset[i] = true;
+#define ALL_CLOCKS 0xFF
+STATIC void i2c_clock_enable(uint8_t mask);
+STATIC void i2c_clock_disable(uint8_t mask);
 
-            never_reset_pin_number(self->scl->pin->port, self->scl->pin->number);
-            never_reset_pin_number(self->sda->pin->port, self->scl->pin->number);
-            break;
+void i2c_reset(void) {
+    uint16_t never_reset_mask = 0x00;
+    for(int i = 0; i < MAX_I2C; i++) {
+        if (!never_reset_i2c[i]) {
+            reserved_i2c[i] = false;
+        } else {
+            never_reset_mask |= 1 << i;
         }
     }
+    i2c_clock_disable(ALL_CLOCKS & ~(never_reset_mask));
 }
 
-
 void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
         const mcu_pin_obj_t* scl, const mcu_pin_obj_t* sda, uint32_t frequency, uint32_t timeout) {
 
     //match pins to I2C objects
     I2C_TypeDef * I2Cx;
+    uint8_t sda_len = MP_ARRAY_SIZE(mcu_i2c_sda_list);
+    uint8_t scl_len = MP_ARRAY_SIZE(mcu_i2c_scl_list);
+    bool i2c_taken = false;
 
-    uint8_t sda_len = sizeof(mcu_i2c_sda_list)/sizeof(*mcu_i2c_sda_list);
-    uint8_t scl_len = sizeof(mcu_i2c_scl_list)/sizeof(*mcu_i2c_scl_list);
-    for(uint i=0; i<sda_len;i++) {
+    for (uint i = 0; i < sda_len; i++) {
         if (mcu_i2c_sda_list[i].pin == sda) {
-            for(uint j=0; j<scl_len;j++) {
+            for (uint j = 0; j < scl_len; j++) {
                 if ((mcu_i2c_scl_list[j].pin == scl)
                     && (mcu_i2c_scl_list[j].i2c_index == mcu_i2c_sda_list[i].i2c_index)) {
+                    //keep looking if the I2C is taken, could be another SCL that works
+                    if (reserved_i2c[mcu_i2c_scl_list[i].i2c_index - 1]) {
+                        i2c_taken = true;
+                        continue;
+                    }
                     self->scl = &mcu_i2c_scl_list[j];
                     self->sda = &mcu_i2c_sda_list[i];
                     break;
@@ -89,14 +84,14 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
     }
 
     //handle typedef selection, errors
-    if(self->sda!=NULL && self->scl!=NULL ) {
-        I2Cx = mcu_i2c_banks[self->sda->i2c_index-1];
+    if (self->sda != NULL && self->scl != NULL ) {
+        I2Cx = mcu_i2c_banks[self->sda->i2c_index - 1];
     } else {
-        mp_raise_RuntimeError(translate("Invalid I2C pin selection"));
-    }
-
-    if(reserved_i2c[self->sda->i2c_index-1]) {
-        mp_raise_RuntimeError(translate("Hardware busy, try alternative pins"));
+        if (i2c_taken) {
+            mp_raise_ValueError(translate("Hardware busy, try alternative pins"));
+        } else {
+            mp_raise_ValueError(translate("Invalid I2C pin selection"));
+        }
     }
 
     //Start GPIO for each pin
@@ -115,44 +110,9 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
     GPIO_InitStruct.Alternate = self->scl->altfn_index; 
     HAL_GPIO_Init(pin_port(scl->port), &GPIO_InitStruct);
 
-    //Fix for HAL error caused by soft reboot GPIO init SDA pin voltage drop. See Eratta. 
-    //Must be in this exact spot or I2C will get stuck in infinite loop. 
-    //TODO: See git issue #2172
-    #ifdef I2C1
-    __HAL_RCC_I2C1_FORCE_RESET();
-    HAL_Delay(2);
-    __HAL_RCC_I2C1_RELEASE_RESET();
-    #endif
-    #ifdef I2C2
-    __HAL_RCC_I2C2_FORCE_RESET();
-    HAL_Delay(2);
-    __HAL_RCC_I2C2_RELEASE_RESET();
-    #endif
-    #ifdef I2C3
-    __HAL_RCC_I2C3_FORCE_RESET();
-    HAL_Delay(2);
-    __HAL_RCC_I2C3_RELEASE_RESET();
-    #endif
-
-    //Keep separate so above hack can be cleanly replaced
-    #ifdef I2C1
-    if(I2Cx==I2C1) { 
-        reserved_i2c[0] = true;
-        __HAL_RCC_I2C1_CLK_ENABLE();
-    } 
-    #endif
-    #ifdef I2C2
-    if(I2Cx==I2C2) {
-        reserved_i2c[1] = true;
-        __HAL_RCC_I2C2_CLK_ENABLE(); 
-    }
-    #endif
-    #ifdef I2C3
-    if(I2Cx==I2C3) {
-        reserved_i2c[2] = true;
-        __HAL_RCC_I2C3_CLK_ENABLE(); 
-    }
-    #endif
+    //Note: due to I2C soft reboot issue, do not relocate clock init.
+    i2c_clock_enable(1 << (self->sda->i2c_index - 1));
+    reserved_i2c[self->sda->i2c_index - 1] = true;
 
     self->handle.Instance = I2Cx;
     self->handle.Init.ClockSpeed = 100000;
@@ -163,13 +123,26 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
     self->handle.Init.OwnAddress2 = 0;
     self->handle.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
     self->handle.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
-    if(HAL_I2C_Init(&(self->handle)) != HAL_OK) {
+    self->handle.State = HAL_I2C_STATE_RESET;
+    if (HAL_I2C_Init(&(self->handle)) != HAL_OK) {
         mp_raise_RuntimeError(translate("I2C Init Error"));
     }
     claim_pin(sda);
     claim_pin(scl);
 }
 
+void common_hal_busio_i2c_never_reset(busio_i2c_obj_t *self) {
+    for (size_t i = 0; i < MP_ARRAY_SIZE(mcu_i2c_banks); i++) {
+        if (self->handle.Instance == mcu_i2c_banks[i]) {
+            never_reset_i2c[i] = true;
+
+            never_reset_pin_number(self->scl->pin->port, self->scl->pin->number);
+            never_reset_pin_number(self->sda->pin->port, self->sda->pin->number);
+            break;
+        }
+    }
+}
+
 bool common_hal_busio_i2c_deinited(busio_i2c_obj_t *self) {
     return self->sda->pin == mp_const_none;
 }
@@ -178,27 +151,11 @@ void common_hal_busio_i2c_deinit(busio_i2c_obj_t *self) {
     if (common_hal_busio_i2c_deinited(self)) {
         return;
     }
-    #ifdef I2C1
-    if(self->handle.Instance==I2C1) {
-        never_reset[0] = false;
-        reserved_i2c[0] = false;
-        __HAL_RCC_I2C1_CLK_DISABLE(); 
-    }
-    #endif
-    #ifdef I2C2
-    if(self->handle.Instance==I2C2) {
-        never_reset[1] = false;
-        reserved_i2c[1] = false;
-        __HAL_RCC_I2C2_CLK_DISABLE(); 
-    }
-    #endif
-    #ifdef I2C3
-    if(self->handle.Instance==I2C3) {
-        never_reset[2] = false;
-        reserved_i2c[2] = false;
-        __HAL_RCC_I2C3_CLK_DISABLE(); 
-    }
-    #endif
+
+    i2c_clock_disable(1 << (self->sda->i2c_index - 1));
+    reserved_i2c[self->sda->i2c_index - 1] = false;
+    never_reset_i2c[self->sda->i2c_index - 1] = false;
+
     reset_pin_number(self->sda->pin->port,self->sda->pin->number);
     reset_pin_number(self->scl->pin->port,self->scl->pin->number);
     self->sda = mp_const_none;
@@ -206,7 +163,7 @@ void common_hal_busio_i2c_deinit(busio_i2c_obj_t *self) {
 }
 
 bool common_hal_busio_i2c_probe(busio_i2c_obj_t *self, uint8_t addr) {
-    return HAL_I2C_IsDeviceReady(&(self->handle), (uint16_t)(addr<<1),2,2) == HAL_OK;
+    return HAL_I2C_IsDeviceReady(&(self->handle), (uint16_t)(addr << 1), 2, 2) == HAL_OK;
 }
 
 bool common_hal_busio_i2c_try_lock(busio_i2c_obj_t *self) {
@@ -238,11 +195,56 @@ void common_hal_busio_i2c_unlock(busio_i2c_obj_t *self) {
 
 uint8_t common_hal_busio_i2c_write(busio_i2c_obj_t *self, uint16_t addr,
                                    const uint8_t *data, size_t len, bool transmit_stop_bit) {
-    HAL_StatusTypeDef result = HAL_I2C_Master_Transmit(&(self->handle), (uint16_t)(addr<<1), (uint8_t *)data, (uint16_t)len, 500);
+    HAL_StatusTypeDef result = HAL_I2C_Master_Transmit(&(self->handle), (uint16_t)(addr << 1), 
+                                                        (uint8_t *)data, (uint16_t)len, 500);
     return result == HAL_OK ? 0 : MP_EIO;
 }
 
 uint8_t common_hal_busio_i2c_read(busio_i2c_obj_t *self, uint16_t addr,
         uint8_t *data, size_t len) {
-    return HAL_I2C_Master_Receive(&(self->handle), (uint16_t)(addr<<1), data, (uint16_t)len, 500) == HAL_OK ? 0 : MP_EIO;
+    return HAL_I2C_Master_Receive(&(self->handle), (uint16_t)(addr<<1), data, (uint16_t)len, 500) 
+                                    == HAL_OK ? 0 : MP_EIO;
+}
+
+STATIC void i2c_clock_enable(uint8_t mask) {
+    //Note: hard reset required due to soft reboot issue. 
+    #ifdef I2C1
+    if (mask & (1 << 0)) {
+        __HAL_RCC_I2C1_CLK_ENABLE();
+        __HAL_RCC_I2C1_FORCE_RESET();
+        __HAL_RCC_I2C1_RELEASE_RESET();
+    }
+    #endif
+    #ifdef I2C2
+    if (mask & (1 << 1)) {
+        __HAL_RCC_I2C2_CLK_ENABLE();
+        __HAL_RCC_I2C2_FORCE_RESET();
+        __HAL_RCC_I2C2_RELEASE_RESET();
+    }
+    #endif
+    #ifdef I2C3
+    if (mask & (1 << 2)) {
+        __HAL_RCC_I2C3_CLK_ENABLE();
+        __HAL_RCC_I2C3_FORCE_RESET();
+        __HAL_RCC_I2C3_RELEASE_RESET();
+    }
+    #endif
+}
+
+STATIC void i2c_clock_disable(uint8_t mask) {
+    #ifdef I2C1
+    if (mask & (1 << 0)) {
+        __HAL_RCC_I2C1_CLK_DISABLE();
+    }
+    #endif
+    #ifdef I2C2
+    if (mask & (1 << 1)) {
+        __HAL_RCC_I2C2_CLK_DISABLE();
+    }
+    #endif
+    #ifdef I2C3
+    if (mask & (1 << 2)) {
+        __HAL_RCC_I2C3_CLK_DISABLE();
+    }
+    #endif
 }
diff --git a/ports/stm32f4/common-hal/busio/SPI.c b/ports/stm32f4/common-hal/busio/SPI.c
index deacedb50..afc6cfcbd 100644
--- a/ports/stm32f4/common-hal/busio/SPI.c
+++ b/ports/stm32f4/common-hal/busio/SPI.c
@@ -39,13 +39,12 @@
 // Note that any bugs introduced in this file can cause crashes at startup
 // for chips using external SPI flash.
 
-#define MAX_SPI 6 //TODO; replace this as part of periph cleanup
-#define ALL_CLOCKS 0xFF
-
 //arrays use 0 based numbering: SPI1 is stored at index 0
+#define MAX_SPI 6
 STATIC bool reserved_spi[MAX_SPI];
 STATIC bool never_reset_spi[MAX_SPI];
 
+#define ALL_CLOCKS 0xFF
 STATIC void spi_clock_enable(uint8_t mask);
 STATIC void spi_clock_disable(uint8_t mask);
 
@@ -60,13 +59,39 @@ STATIC uint32_t get_busclock(SPI_TypeDef * instance) {
     return HAL_RCC_GetPCLK2Freq();
 }
 
+STATIC uint32_t stm32_baud_to_spi_div(uint32_t baudrate, uint16_t * prescaler, uint32_t busclock) {
+    static const uint32_t baud_map[8][2] = {
+        {2,SPI_BAUDRATEPRESCALER_2},
+        {4,SPI_BAUDRATEPRESCALER_4},
+        {8,SPI_BAUDRATEPRESCALER_8},
+        {16,SPI_BAUDRATEPRESCALER_16},
+        {32,SPI_BAUDRATEPRESCALER_32},
+        {64,SPI_BAUDRATEPRESCALER_64},
+        {128,SPI_BAUDRATEPRESCALER_128},
+        {256,SPI_BAUDRATEPRESCALER_256}
+    };
+    size_t i = 0;
+    uint16_t divisor;
+    do {
+        divisor = baud_map[i][0];
+        if (baudrate >= (busclock/divisor)) {
+            *prescaler = divisor;
+            return baud_map[i][1];
+        }
+        i++;
+    } while (divisor != 256);
+    //only gets here if requested baud is lower than minimum
+    *prescaler = 256;
+    return SPI_BAUDRATEPRESCALER_256;
+}
+
 void spi_reset(void) {
     uint16_t never_reset_mask = 0x00;
-    for(int i=0;i<MAX_SPI;i++) {
+    for (int i = 0; i < MAX_SPI; i++) {
         if (!never_reset_spi[i]) {
-            reserved_spi[i] = 0x00;
+            reserved_spi[i] = false;
         } else {
-            never_reset_mask |= 1<<i;
+            never_reset_mask |= 1 << i;
         }
     }
     spi_clock_disable(ALL_CLOCKS & ~(never_reset_mask));
@@ -79,26 +104,26 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
     //match pins to SPI objects
     SPI_TypeDef * SPIx;
 
-    uint8_t sck_len = sizeof(mcu_spi_sck_list)/sizeof(*mcu_spi_sck_list);
-    uint8_t mosi_len = sizeof(mcu_spi_mosi_list)/sizeof(*mcu_spi_mosi_list);
-    uint8_t miso_len = sizeof(mcu_spi_miso_list)/sizeof(*mcu_spi_miso_list);
+    uint8_t sck_len = MP_ARRAY_SIZE(mcu_spi_sck_list);
+    uint8_t mosi_len = MP_ARRAY_SIZE(mcu_spi_mosi_list);
+    uint8_t miso_len = MP_ARRAY_SIZE(mcu_spi_miso_list);
     bool spi_taken = false;
 
     //SCK is not optional. MOSI and MISO are
-    for (uint i=0; i<sck_len;i++) {
+    for (uint i = 0; i < sck_len; i++) {
         if (mcu_spi_sck_list[i].pin == sck) {
             //if both MOSI and MISO exist, loop search normally
             if ((mosi != mp_const_none) && (miso != mp_const_none)) {
                 //MOSI
-                for (uint j=0; j<mosi_len;j++) {
+                for (uint j = 0; j < mosi_len; j++) {
                     if (mcu_spi_mosi_list[j].pin == mosi) {
                         //MISO
-                        for (uint k=0; k<miso_len;k++) {
+                        for (uint k = 0; k < miso_len; k++) {
                             if ((mcu_spi_miso_list[k].pin == miso) //everything needs the same index
                                 && (mcu_spi_sck_list[i].spi_index == mcu_spi_mosi_list[j].spi_index)
                                 && (mcu_spi_sck_list[i].spi_index == mcu_spi_miso_list[k].spi_index)) {
                                 //keep looking if the SPI is taken, edge case
-                                if (reserved_spi[mcu_spi_sck_list[i].spi_index-1]) {
+                                if (reserved_spi[mcu_spi_sck_list[i].spi_index - 1]) {
                                     spi_taken = true;
                                     continue;
                                 }
@@ -113,11 +138,11 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
                 }
             // if just MISO, reduce search
             } else if (miso != mp_const_none) {
-                for (uint j=0; j<miso_len;j++) {
+                for (uint j = 0; j < miso_len; j++) {
                     if ((mcu_spi_miso_list[j].pin == miso) //only SCK and MISO need the same index
                         && (mcu_spi_sck_list[i].spi_index == mcu_spi_miso_list[j].spi_index)) {
                         //keep looking if the SPI is taken, edge case
-                        if (reserved_spi[mcu_spi_sck_list[i].spi_index-1]) {
+                        if (reserved_spi[mcu_spi_sck_list[i].spi_index - 1]) {
                             spi_taken = true;
                             continue;
                         }
@@ -130,11 +155,11 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
                 }  
             // if just MOSI, reduce search
             } else if (mosi != mp_const_none) {
-                for (uint j=0; j<mosi_len;j++) {
+                for (uint j = 0; j < mosi_len; j++) {
                     if ((mcu_spi_mosi_list[j].pin == mosi) //only SCK and MOSI need the same index
                         && (mcu_spi_sck_list[i].spi_index == mcu_spi_mosi_list[j].spi_index)) {
                         //keep looking if the SPI is taken, edge case
-                        if (reserved_spi[mcu_spi_sck_list[i].spi_index-1]) {
+                        if (reserved_spi[mcu_spi_sck_list[i].spi_index - 1]) {
                             spi_taken = true;
                             continue;
                         }
@@ -153,10 +178,10 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
     }
 
     //handle typedef selection, errors
-    if ( (self->sck!=NULL && self->mosi!=NULL && self->miso != NULL) ||
-        (self->sck!=NULL && self->mosi!=NULL && miso == mp_const_none) ||
-        (self->sck!=NULL && self->miso!=NULL && mosi == mp_const_none)) {
-        SPIx = mcu_spi_banks[self->sck->spi_index-1];
+    if ( (self->sck != NULL && self->mosi != NULL && self->miso != NULL) ||
+        (self->sck != NULL && self->mosi != NULL && miso == mp_const_none) ||
+        (self->sck != NULL && self->miso != NULL && mosi == mp_const_none)) {
+        SPIx = mcu_spi_banks[self->sck->spi_index - 1];
     } else {
         if (spi_taken) {
             mp_raise_ValueError(translate("Hardware busy, try alternative pins"));
@@ -192,7 +217,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
         HAL_GPIO_Init(pin_port(miso->port), &GPIO_InitStruct);
     }
 
-    spi_clock_enable(1<<(self->sck->spi_index - 1));
+    spi_clock_enable(1 << (self->sck->spi_index - 1));
     reserved_spi[self->sck->spi_index - 1] = true;
     
     self->handle.Instance = SPIx; 
@@ -212,7 +237,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
     {
         mp_raise_ValueError(translate("SPI Init Error"));
     }
-    self->baudrate = (get_busclock(SPIx)/16);
+    self->baudrate = (get_busclock(SPIx) / 16);
     self->prescaler = 16;
     self->polarity = 0;
     self->phase = 0;
@@ -228,7 +253,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
 }
 
 void common_hal_busio_spi_never_reset(busio_spi_obj_t *self) {
-    for (size_t i = 0 ; i < MP_ARRAY_SIZE(mcu_spi_banks); i++) {
+    for (size_t i = 0; i < MP_ARRAY_SIZE(mcu_spi_banks); i++) {
         if (mcu_spi_banks[i] == self->handle.Instance) {
             never_reset_spi[i] = true;
             never_reset_pin_number(self->sck->pin->port, self->sck->pin->number);
@@ -248,6 +273,9 @@ bool common_hal_busio_spi_deinited(busio_spi_obj_t *self) {
 }
 
 void common_hal_busio_spi_deinit(busio_spi_obj_t *self) {
+    if (common_hal_busio_spi_deinited(self)) {
+        return;
+    }
     spi_clock_disable(1<<(self->sck->spi_index - 1));
     reserved_spi[self->sck->spi_index - 1] = false;
     never_reset_spi[self->sck->spi_index - 1] = false;
@@ -264,32 +292,6 @@ void common_hal_busio_spi_deinit(busio_spi_obj_t *self) {
     self->miso = mp_const_none;
 }
 
-STATIC uint32_t stm32_baud_to_spi_div(uint32_t baudrate, uint16_t * prescaler, uint32_t busclock) {
-    static const uint32_t baud_map[8][2] = {
-        {2,SPI_BAUDRATEPRESCALER_2},
-        {4,SPI_BAUDRATEPRESCALER_4},
-        {8,SPI_BAUDRATEPRESCALER_8},
-        {16,SPI_BAUDRATEPRESCALER_16},
-        {32,SPI_BAUDRATEPRESCALER_32},
-        {64,SPI_BAUDRATEPRESCALER_64},
-        {128,SPI_BAUDRATEPRESCALER_128},
-        {256,SPI_BAUDRATEPRESCALER_256}
-    };
-    size_t i = 0;
-    uint16_t divisor;
-    do {
-        divisor = baud_map[i][0];
-        if (baudrate >= (busclock/divisor)) {
-            *prescaler = divisor;
-            return baud_map[i][1];
-        }
-        i++;
-    } while (divisor != 256);
-    //only gets here if requested baud is lower than minimum
-    *prescaler = 256;
-    return SPI_BAUDRATEPRESCALER_256;
-}
-
 bool common_hal_busio_spi_configure(busio_spi_obj_t *self,
         uint32_t baudrate, uint8_t polarity, uint8_t phase, uint8_t bits) {
     //This resets the SPI, so check before updating it redundantly
@@ -391,42 +393,66 @@ uint8_t common_hal_busio_spi_get_polarity(busio_spi_obj_t* self) {
 
 STATIC void spi_clock_enable(uint8_t mask) {
     #ifdef SPI1
-    if (mask & 1<<0) __HAL_RCC_SPI1_CLK_ENABLE();
+    if (mask & (1 << 0)) {
+        __HAL_RCC_SPI1_CLK_ENABLE();
+    }
     #endif
     #ifdef SPI2
-    if (mask & 1<<1) __HAL_RCC_SPI2_CLK_ENABLE();
+    if (mask & (1 << 1)) {
+        __HAL_RCC_SPI2_CLK_ENABLE();
+    }
     #endif
     #ifdef SPI3
-    if (mask & 1<<2) __HAL_RCC_SPI3_CLK_ENABLE();
+    if (mask & (1 << 2)) {
+        __HAL_RCC_SPI3_CLK_ENABLE();
+    }
     #endif
     #ifdef SPI4
-    if (mask & 1<<3) __HAL_RCC_SPI4_CLK_ENABLE();
+    if (mask & (1 << 3)) {
+        __HAL_RCC_SPI4_CLK_ENABLE();
+    }
     #endif
     #ifdef SPI5
-    if (mask & 1<<4) __HAL_RCC_SPI5_CLK_ENABLE();
+    if (mask & (1 << 4)) {
+        __HAL_RCC_SPI5_CLK_ENABLE();
+    }
     #endif
     #ifdef SPI6
-    if (mask & 1<<5) __HAL_RCC_SPI6_CLK_ENABLE();
+    if (mask & (1 << 5)) {
+        __HAL_RCC_SPI6_CLK_ENABLE();
+    }
     #endif
 }
 
 STATIC void spi_clock_disable(uint8_t mask) {
     #ifdef SPI1
-    if (mask & 1<<0) __HAL_RCC_SPI1_CLK_DISABLE();
+    if (mask & (1 << 0)) {
+        __HAL_RCC_SPI1_CLK_DISABLE();
+    }
     #endif
     #ifdef SPI2
-    if (mask & 1<<1) __HAL_RCC_SPI2_CLK_DISABLE();
+    if (mask & (1 << 1)) {
+        __HAL_RCC_SPI2_CLK_DISABLE();
+    }
     #endif
     #ifdef SPI3
-    if (mask & 1<<2) __HAL_RCC_SPI3_CLK_DISABLE();
+    if (mask & (1 << 2)) {
+        __HAL_RCC_SPI3_CLK_DISABLE();
+    }
     #endif
     #ifdef SPI4
-    if (mask & 1<<3) __HAL_RCC_SPI4_CLK_DISABLE();
+    if (mask & (1 << 3)) {
+        __HAL_RCC_SPI4_CLK_DISABLE();
+    }
     #endif
     #ifdef SPI5
-    if (mask & 1<<4) __HAL_RCC_SPI5_CLK_DISABLE();
+    if (mask & (1 << 4)) {
+        __HAL_RCC_SPI5_CLK_DISABLE();
+    }
     #endif
     #ifdef SPI6
-    if (mask & 1<<5) __HAL_RCC_SPI6_CLK_DISABLE();
+    if (mask & (1 << 5)) {
+        __HAL_RCC_SPI6_CLK_DISABLE();
+    }
     #endif
 }
diff --git a/ports/stm32f4/common-hal/busio/UART.c b/ports/stm32f4/common-hal/busio/UART.c
index aa792dae1..bfa541c17 100644
--- a/ports/stm32f4/common-hal/busio/UART.c
+++ b/ports/stm32f4/common-hal/busio/UART.c
@@ -40,6 +40,7 @@
 
 #define ALL_UARTS 0xFFFF
 
+//arrays use 0 based numbering: UART1 is stored at index 0
 STATIC bool reserved_uart[MAX_UART];
 int errflag; //Used to restart read halts
 
@@ -47,14 +48,6 @@ STATIC void uart_clock_enable(uint16_t mask);
 STATIC void uart_clock_disable(uint16_t mask);
 STATIC void uart_assign_irq(busio_uart_obj_t* self, USART_TypeDef* USARTx);
 
-void uart_reset(void) {
-    for (uint8_t i = 0; i < MAX_UART; i++) {
-        reserved_uart[i] = false;
-        MP_STATE_PORT(cpy_uart_obj_all)[i] = NULL;
-    }
-    uart_clock_disable(ALL_UARTS);
-}
-
 STATIC USART_TypeDef * assign_uart_or_throw(busio_uart_obj_t* self, bool pin_eval,
                                             int uart_index, bool uart_taken) {
     if (pin_eval) {
@@ -70,6 +63,14 @@ STATIC USART_TypeDef * assign_uart_or_throw(busio_uart_obj_t* self, bool pin_eva
     }
 }
 
+void uart_reset(void) {
+    for (uint8_t i = 0; i < MAX_UART; i++) {
+        reserved_uart[i] = false;
+        MP_STATE_PORT(cpy_uart_obj_all)[i] = NULL;
+    }
+    uart_clock_disable(ALL_UARTS);
+}
+
 void common_hal_busio_uart_construct(busio_uart_obj_t* self,
         const mcu_pin_obj_t* tx, const mcu_pin_obj_t* rx, uint32_t baudrate,
         uint8_t bits, uart_parity_t parity, uint8_t stop, mp_float_t timeout,
@@ -78,8 +79,8 @@ void common_hal_busio_uart_construct(busio_uart_obj_t* self,
     //match pins to UART objects
     USART_TypeDef * USARTx;
 
-    uint8_t tx_len = sizeof(mcu_uart_tx_list)/sizeof(*mcu_uart_tx_list);
-    uint8_t rx_len = sizeof(mcu_uart_rx_list)/sizeof(*mcu_uart_rx_list);
+    uint8_t tx_len = MP_ARRAY_SIZE(mcu_uart_tx_list);
+    uint8_t rx_len = MP_ARRAY_SIZE(mcu_uart_rx_list);
     bool uart_taken = false;
     uint8_t uart_index = 0; //origin 0 corrected
 
@@ -567,33 +568,53 @@ STATIC void uart_clock_disable(uint16_t mask) {
 
 STATIC void uart_assign_irq(busio_uart_obj_t *self, USART_TypeDef * USARTx) {
     #ifdef USART1
-    if (USARTx == USART1) self->irq = USART1_IRQn;
+    if (USARTx == USART1) {
+        self->irq = USART1_IRQn;
+    }
     #endif
     #ifdef USART2
-    if (USARTx == USART2) self->irq = USART2_IRQn;
+    if (USARTx == USART2) {
+        self->irq = USART2_IRQn;
+    }
     #endif
     #ifdef USART3
-    if (USARTx == USART3) self->irq = USART3_IRQn;
+    if (USARTx == USART3) {
+        self->irq = USART3_IRQn;
+    }
     #endif
     #ifdef UART4
-    if (USARTx == UART4) self->irq = UART4_IRQn;
+    if (USARTx == UART4) {
+        self->irq = UART4_IRQn;
+    }
     #endif
     #ifdef UART5
-    if (USARTx == UART5) self->irq = UART5_IRQn;
+    if (USARTx == UART5) {
+        self->irq = UART5_IRQn;
+    }
     #endif
     #ifdef USART6
-    if (USARTx == USART6) self->irq = USART6_IRQn;
+    if (USARTx == USART6) {
+        self->irq = USART6_IRQn;
+    }
     #endif
     #ifdef UART7
-    if (USARTx == UART7) self->irq = UART7_IRQn;
+    if (USARTx == UART7) {
+        self->irq = UART7_IRQn;
+    }
     #endif
     #ifdef UART8
-    if (USARTx == UART8) self->irq = UART8_IRQn;
+    if (USARTx == UART8) {
+        self->irq = UART8_IRQn;
+    }
     #endif
     #ifdef UART9
-    if (USARTx == UART9) self->irq = UART9_IRQn;
+    if (USARTx == UART9) {
+        self->irq = UART9_IRQn;
+    }
     #endif
     #ifdef UART10
-    if (USARTx == UART10) self->irq = UART10_IRQn;
+    if (USARTx == UART10) {
+        self->irq = UART10_IRQn;
+    }
     #endif
 }
diff --git a/ports/stm32f4/common-hal/pulseio/PWMOut.c b/ports/stm32f4/common-hal/pulseio/PWMOut.c
index 7bff8de76..ea9f67881 100644
--- a/ports/stm32f4/common-hal/pulseio/PWMOut.c
+++ b/ports/stm32f4/common-hal/pulseio/PWMOut.c
@@ -69,15 +69,15 @@ STATIC uint32_t timer_get_source_freq(uint32_t tim_id) {
 
 STATIC uint32_t timer_get_internal_duty(uint16_t duty, uint32_t period) {
     //duty cycle is duty/0xFFFF fraction x (number of pulses per period)
-    return (duty*period)/((1<<16)-1);
+    return (duty*period) / ((1 << 16) - 1);
 }
 
 STATIC void timer_get_optimal_divisors(uint32_t*period, uint32_t*prescaler, 
                                        uint32_t frequency, uint32_t source_freq) {
     //Find the largest possible period supported by this frequency
-    for (int i=0; i<(1 << 16);i++) {
-        *period = source_freq/(i*frequency);
-        if (*period < (1 << 16) && *period>=2) {
+    for (int i = 0; i < (1 << 16); i++) {
+        *period = source_freq / (i * frequency);
+        if (*period < (1 << 16) && *period >= 2) {
             *prescaler = i;
             break;
         }
@@ -89,60 +89,41 @@ STATIC void timer_get_optimal_divisors(uint32_t*period, uint32_t*prescaler,
 
 void pwmout_reset(void) {
     uint16_t never_reset_mask = 0x00;
-    for(int i=0;i<TIM_BANK_ARRAY_LEN;i++) {
+    for (int i = 0; i < TIM_BANK_ARRAY_LEN; i++) {
         if (!never_reset_tim[i]) {
             reserved_tim[i] = 0x00;
             tim_frequencies[i] = 0x00;
         } else {
-            never_reset_mask |= 1<<i;
+            never_reset_mask |= 1 << i;
         }
     }
     tim_clock_disable(ALL_CLOCKS & ~(never_reset_mask));
 }
 
-void common_hal_pulseio_pwmout_never_reset(pulseio_pwmout_obj_t *self) {
-    for(size_t i = 0 ; i < TIM_BANK_ARRAY_LEN; i++) {
-        if (mcu_tim_banks[i] == self->handle.Instance) {
-            never_reset_tim[i] = true;
-            never_reset_pin_number(self->tim->pin->port, self->tim->pin->number);
-            break;
-        }
-    }
-}
-
-void common_hal_pulseio_pwmout_reset_ok(pulseio_pwmout_obj_t *self) {
-    for(size_t i = 0 ; i < TIM_BANK_ARRAY_LEN; i++) {
-        if (mcu_tim_banks[i] == self->handle.Instance) {
-            never_reset_tim[i] = false;
-            break;
-        }
-    }
-}
-
 pwmout_result_t common_hal_pulseio_pwmout_construct(pulseio_pwmout_obj_t* self,
                                                     const mcu_pin_obj_t* pin,
                                                     uint16_t duty,
                                                     uint32_t frequency,
                                                     bool variable_frequency) {
     TIM_TypeDef * TIMx;
-    uint8_t tim_num = sizeof(mcu_tim_pin_list)/sizeof(*mcu_tim_pin_list);
+    uint8_t tim_num = MP_ARRAY_SIZE(mcu_tim_pin_list);
     bool tim_chan_taken = false;
     bool tim_taken_f_mismatch = false;
     bool var_freq_mismatch = false;
     bool first_time_setup = true;
     mcu_tim_pin_obj_t l_tim = {0};
 
-    for(uint i = 0; i < tim_num; i++) {
+    for (uint i = 0; i < tim_num; i++) {
         l_tim = mcu_tim_pin_list[i];
-        uint8_t l_tim_index = l_tim.tim_index-1;
-        uint8_t l_tim_channel = l_tim.channel_index-1;
+        uint8_t l_tim_index = l_tim.tim_index - 1;
+        uint8_t l_tim_channel = l_tim.channel_index - 1;
 
         //if pin is same
         if (l_tim.pin == pin) {
             //check if the timer has a channel active
             if (reserved_tim[l_tim_index] != 0) {
                 //is it the same channel? (or all channels reserved by a var-freq)
-                if (reserved_tim[l_tim_index] & 1<<(l_tim_channel)) {
+                if (reserved_tim[l_tim_index] & 1 << (l_tim_channel)) {
                     tim_chan_taken = true;
                     continue; //keep looking, might be another viable option
                 }
@@ -165,21 +146,21 @@ pwmout_result_t common_hal_pulseio_pwmout_construct(pulseio_pwmout_obj_t* self,
     }
 
     //handle valid/invalid timer instance
-    if (self->tim!=NULL) {
+    if (self->tim != NULL) {
         //create instance
-        TIMx = mcu_tim_banks[self->tim->tim_index-1];
+        TIMx = mcu_tim_banks[self->tim->tim_index - 1];
         //reserve timer/channel
         if (variable_frequency) {
-            reserved_tim[self->tim->tim_index-1] = 0x0F;
+            reserved_tim[self->tim->tim_index - 1] = 0x0F;
         } else {
-            reserved_tim[self->tim->tim_index-1] |= 1<<(self->tim->channel_index-1);
+            reserved_tim[self->tim->tim_index - 1] |= 1 << (self->tim->channel_index - 1);
         }
-        tim_frequencies[self->tim->tim_index-1] = frequency;
+        tim_frequencies[self->tim->tim_index - 1] = frequency;
     } else { //no match found
         if (tim_chan_taken) {
             mp_raise_ValueError(translate("No more timers available on this pin."));
         } else if (tim_taken_f_mismatch) {
-            mp_raise_ValueError(translate("Frequency must be the same as as the existing PWMOut using this timer"));
+            mp_raise_ValueError(translate("Frequency must match existing PWMOut using this timer"));
         } else if (var_freq_mismatch) {
             mp_raise_ValueError(translate("Cannot vary frequency on a timer that is already in use"));
         } else {
@@ -195,14 +176,15 @@ pwmout_result_t common_hal_pulseio_pwmout_construct(pulseio_pwmout_obj_t* self,
     GPIO_InitStruct.Alternate = self->tim->altfn_index;
     HAL_GPIO_Init(pin_port(pin->port), &GPIO_InitStruct);
 
-    tim_clock_enable(1<<(self->tim->tim_index - 1));
+    tim_clock_enable(1 << (self->tim->tim_index - 1));
 
     //translate channel into handle value
     self->channel = 4 * (self->tim->channel_index - 1);
 
     uint32_t prescaler = 0; //prescaler is 15 bit
     uint32_t period = 0; //period is 16 bit
-    timer_get_optimal_divisors(&period, &prescaler,frequency,timer_get_source_freq(self->tim->tim_index));
+    timer_get_optimal_divisors(&period, &prescaler, frequency, 
+                            timer_get_source_freq(self->tim->tim_index));
 
     //Timer init
     self->handle.Instance = TIMx;
@@ -242,6 +224,25 @@ pwmout_result_t common_hal_pulseio_pwmout_construct(pulseio_pwmout_obj_t* self,
     return PWMOUT_OK;
 }
 
+void common_hal_pulseio_pwmout_never_reset(pulseio_pwmout_obj_t *self) {
+    for (size_t i = 0; i < TIM_BANK_ARRAY_LEN; i++) {
+        if (mcu_tim_banks[i] == self->handle.Instance) {
+            never_reset_tim[i] = true;
+            never_reset_pin_number(self->tim->pin->port, self->tim->pin->number);
+            break;
+        }
+    }
+}
+
+void common_hal_pulseio_pwmout_reset_ok(pulseio_pwmout_obj_t *self) {
+    for(size_t i = 0; i < TIM_BANK_ARRAY_LEN; i++) {
+        if (mcu_tim_banks[i] == self->handle.Instance) {
+            never_reset_tim[i] = false;
+            break;
+        }
+    }
+}
+
 bool common_hal_pulseio_pwmout_deinited(pulseio_pwmout_obj_t* self) {
     return self->tim == mp_const_none;
 }
@@ -252,18 +253,18 @@ void common_hal_pulseio_pwmout_deinit(pulseio_pwmout_obj_t* self) {
     }
     //var freq shuts down entire timer, others just their channel
     if (self->variable_frequency) {
-        reserved_tim[self->tim->tim_index-1] = 0x00;
+        reserved_tim[self->tim->tim_index - 1] = 0x00;
     } else {
-        reserved_tim[self->tim->tim_index-1] &= ~(1<<self->tim->channel_index);
+        reserved_tim[self->tim->tim_index - 1] &= ~(1 << self->tim->channel_index);
         HAL_TIM_PWM_Stop(&self->handle, self->channel);
     }
     reset_pin_number(self->tim->pin->port,self->tim->pin->number);
     self->tim = mp_const_none;
 
     //if reserved timer has no active channels, we can disable it
-    if (!reserved_tim[self->tim->tim_index-1]) {
-        tim_frequencies[self->tim->tim_index-1] = 0x00;
-        tim_clock_disable(1<<(self->tim->tim_index-1));
+    if (!reserved_tim[self->tim->tim_index - 1]) {
+        tim_frequencies[self->tim->tim_index - 1] = 0x00;
+        tim_clock_disable(1 << (self->tim->tim_index - 1));
     }
 }
 
@@ -279,11 +280,14 @@ uint16_t common_hal_pulseio_pwmout_get_duty_cycle(pulseio_pwmout_obj_t* self) {
 
 void common_hal_pulseio_pwmout_set_frequency(pulseio_pwmout_obj_t* self, uint32_t frequency) {
     //don't halt setup for the same frequency
-    if (frequency == self->frequency) return;
+    if (frequency == self->frequency) { 
+        return;
+    }
 
     uint32_t prescaler = 0;
     uint32_t period = 0;
-    timer_get_optimal_divisors(&period, &prescaler,frequency,timer_get_source_freq(self->tim->tim_index));
+    timer_get_optimal_divisors(&period, &prescaler, frequency, 
+                                timer_get_source_freq(self->tim->tim_index));
 
     //shut down
     HAL_TIM_PWM_Stop(&self->handle, self->channel);
@@ -306,7 +310,7 @@ void common_hal_pulseio_pwmout_set_frequency(pulseio_pwmout_obj_t* self, uint32_
         mp_raise_ValueError(translate("Could not restart PWM"));
     }
 
-    tim_frequencies[self->tim->tim_index-1] = frequency;
+    tim_frequencies[self->tim->tim_index - 1] = frequency;
     self->frequency = frequency;
     self->period = period;
 }
@@ -321,80 +325,128 @@ bool common_hal_pulseio_pwmout_get_variable_frequency(pulseio_pwmout_obj_t* self
 
 STATIC void tim_clock_enable(uint16_t mask) {
     #ifdef TIM1
-    if (mask & 1<<0) __HAL_RCC_TIM1_CLK_ENABLE();
+    if (mask & (1 << 0)) {
+        __HAL_RCC_TIM1_CLK_ENABLE();
+    }
     #endif
     #ifdef TIM2
-    if (mask & 1<<1) __HAL_RCC_TIM2_CLK_ENABLE();
+    if (mask & (1 << 1)) {
+        __HAL_RCC_TIM2_CLK_ENABLE();
+    }
     #endif
     #ifdef TIM3
-    if (mask & 1<<2) __HAL_RCC_TIM3_CLK_ENABLE();
+    if (mask & (1 << 2)) {
+        __HAL_RCC_TIM3_CLK_ENABLE();
+    }
     #endif
     #ifdef TIM4
-    if (mask & 1<<3) __HAL_RCC_TIM4_CLK_ENABLE();
+    if (mask & (1 << 3)) {
+        __HAL_RCC_TIM4_CLK_ENABLE();
+    }
     #endif
     #ifdef TIM5
-    if (mask & 1<<4) __HAL_RCC_TIM5_CLK_ENABLE();
+    if (mask & (1 << 4)) {
+        __HAL_RCC_TIM5_CLK_ENABLE();
+    }
     #endif
     //6 and 7 are reserved ADC timers
     #ifdef TIM8
-    if (mask & 1<<7) __HAL_RCC_TIM8_CLK_ENABLE();
+    if (mask & (1 << 7)) {
+        __HAL_RCC_TIM8_CLK_ENABLE();
+    }
     #endif
     #ifdef TIM9
-    if (mask & 1<<8) __HAL_RCC_TIM9_CLK_ENABLE();
+    if (mask & (1 << 8)) {
+        __HAL_RCC_TIM9_CLK_ENABLE();
+    }
     #endif
     #ifdef TIM10
-    if (mask & 1<<9) __HAL_RCC_TIM10_CLK_ENABLE();
+    if (mask & (1 << 9)) {
+        __HAL_RCC_TIM10_CLK_ENABLE();
+    }
     #endif
     #ifdef TIM11
-    if (mask & 1<<10) __HAL_RCC_TIM11_CLK_ENABLE();
+    if (mask & (1 << 10)) {
+        __HAL_RCC_TIM11_CLK_ENABLE();
+    }
     #endif
     #ifdef TIM12
-    if (mask & 1<<11) __HAL_RCC_TIM12_CLK_ENABLE();
+    if (mask & (1 << 11)) {
+        __HAL_RCC_TIM12_CLK_ENABLE();
+    }
     #endif
     #ifdef TIM13
-    if (mask & 1<<12) __HAL_RCC_TIM13_CLK_ENABLE();
+    if (mask & (1 << 12)) {
+        __HAL_RCC_TIM13_CLK_ENABLE();
+    }
     #endif
     #ifdef TIM14
-    if (mask & 1<<13) __HAL_RCC_TIM14_CLK_ENABLE();
+    if (mask & (1 << 13)) {
+        __HAL_RCC_TIM14_CLK_ENABLE();
+    }
     #endif
 }
 
 STATIC void tim_clock_disable(uint16_t mask) {
     #ifdef TIM1
-    if (mask & 1<<0) __HAL_RCC_TIM1_CLK_DISABLE();
+    if (mask & (1 << 0)) {
+        __HAL_RCC_TIM1_CLK_DISABLE();
+    }
     #endif
     #ifdef TIM2
-    if (mask & 1<<1) __HAL_RCC_TIM2_CLK_DISABLE();
+    if (mask & (1 << 1)) {
+        __HAL_RCC_TIM2_CLK_DISABLE();
+    }
     #endif
     #ifdef TIM3
-    if (mask & 1<<2) __HAL_RCC_TIM3_CLK_DISABLE();
+    if (mask & (1 << 2)) {
+        __HAL_RCC_TIM3_CLK_DISABLE();
+    }
     #endif
     #ifdef TIM4
-    if (mask & 1<<3) __HAL_RCC_TIM4_CLK_DISABLE();
+    if (mask & (1 << 3)) {
+        __HAL_RCC_TIM4_CLK_DISABLE();
+    }
     #endif
     #ifdef TIM5
-    if (mask & 1<<4) __HAL_RCC_TIM5_CLK_DISABLE();
+    if (mask & (1 << 4)) {
+        __HAL_RCC_TIM5_CLK_DISABLE();
+    }
     #endif
     //6 and 7 are reserved ADC timers
     #ifdef TIM8
-    if (mask & 1<<7) __HAL_RCC_TIM8_CLK_DISABLE();
+    if (mask & (1 << 7)) {
+        __HAL_RCC_TIM8_CLK_DISABLE();
+    }
     #endif
     #ifdef TIM9
-    if (mask & 1<<8) __HAL_RCC_TIM9_CLK_DISABLE();
+    if (mask & (1 << 8)) {
+        __HAL_RCC_TIM9_CLK_DISABLE();
+    }
     #endif
     #ifdef TIM10
-    if (mask & 1<<9) __HAL_RCC_TIM10_CLK_DISABLE();
+    if (mask & (1 << 9)) {
+        __HAL_RCC_TIM10_CLK_DISABLE();
+    }
     #endif
     #ifdef TIM11
-    if (mask & 1<<10) __HAL_RCC_TIM11_CLK_DISABLE();
+    if (mask & (1 << 10)) {
+        __HAL_RCC_TIM11_CLK_DISABLE();
+    }
     #endif
     #ifdef TIM12
-    if (mask & 1<<11) __HAL_RCC_TIM12_CLK_DISABLE();
+    if (mask & (1 << 11)) {
+        __HAL_RCC_TIM12_CLK_DISABLE();
+    }
     #endif
     #ifdef TIM13
-    if (mask & 1<<12) __HAL_RCC_TIM13_CLK_DISABLE();
+    if (mask & (1 << 12)) {
+        __HAL_RCC_TIM13_CLK_DISABLE();
+    }
     #endif
     #ifdef TIM14
-    if (mask & 1<<13) __HAL_RCC_TIM14_CLK_DISABLE();
+    if (mask & (1 << 13)) {
+        __HAL_RCC_TIM14_CLK_DISABLE();
+    }
     #endif
 }
diff --git a/ports/stm32f4/mpconfigport.mk b/ports/stm32f4/mpconfigport.mk
index 42f390572..f214282cb 100644
--- a/ports/stm32f4/mpconfigport.mk
+++ b/ports/stm32f4/mpconfigport.mk
@@ -69,9 +69,7 @@ ifndef CIRCUITPY_DISPLAYIO
 CIRCUITPY_DISPLAYIO = 1
 endif
 
-ifndef MICROPY_CPYTHON_COMPAT
-MICROPY_CPYTHON_COMPAT = 1
-endif
+CFLAGS += -DMICROPY_CPYTHON_COMPAT=1
 
 #ifeq ($(MCU_SUB_VARIANT), stm32f412zx)
 #endif
diff --git a/py/circuitpy_mpconfig.h b/py/circuitpy_mpconfig.h
index 8c7454cf2..5b705a088 100644
--- a/py/circuitpy_mpconfig.h
+++ b/py/circuitpy_mpconfig.h
@@ -182,7 +182,10 @@ typedef long mp_off_t;
 
 // Remove some lesser-used functionality to make small builds fit.
 #define MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG (CIRCUITPY_FULL_BUILD)
-#define MICROPY_CPYTHON_COMPAT                (CIRCUITPY_FULL_BUILD)
+//TODO: replace this with a rework of the FULL_BUILD system
+#if !defined(MICROPY_CPYTHON_COMPAT)
+	#define MICROPY_CPYTHON_COMPAT                (CIRCUITPY_FULL_BUILD)
+#endif
 #define MICROPY_MODULE_WEAK_LINKS             (CIRCUITPY_FULL_BUILD)
 #define MICROPY_PY_ALL_SPECIAL_METHODS        (CIRCUITPY_FULL_BUILD)
 #define MICROPY_PY_BUILTINS_COMPLEX           (CIRCUITPY_FULL_BUILD)
diff --git a/py/circuitpy_mpconfig.mk b/py/circuitpy_mpconfig.mk
index a464583f3..93175e136 100644
--- a/py/circuitpy_mpconfig.mk
+++ b/py/circuitpy_mpconfig.mk
@@ -310,6 +310,13 @@ CIRCUITPY_BITBANG_APA102 = 0
 endif
 CFLAGS += -DCIRCUITPY_BITBANG_APA102=$(CIRCUITPY_BITBANG_APA102)
 
+# Should busio.I2C() check for pullups?
+# Some boards in combination with certain peripherals may not want this.
+ifndef CIRCUITPY_REQUIRE_I2C_PULLUPS
+CIRCUITPY_REQUIRE_I2C_PULLUPS = 1
+endif
+CFLAGS += -DCIRCUITPY_REQUIRE_I2C_PULLUPS=$(CIRCUITPY_REQUIRE_I2C_PULLUPS)
+
 # REPL over BLE
 ifndef CIRCUITPY_SERIAL_BLE
 CIRCUITPY_SERIAL_BLE = 0
diff --git a/py/objnamedtuple.c b/py/objnamedtuple.c
index a0a64f9b2..84dcf7909 100644
--- a/py/objnamedtuple.c
+++ b/py/objnamedtuple.c
@@ -71,15 +71,6 @@ void namedtuple_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t ki
     mp_obj_attrtuple_print_helper(print, fields, &o->tuple);
 }
 
-mp_obj_t namedtuple_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
-    mp_obj_type_t *type = mp_obj_get_type(self_in);
-    // Check for subclasses of namedtuple and unpack if needed.
-    if (type->parent != &mp_type_tuple) {
-        self_in = ((mp_obj_instance_t*) self_in)->subobj[0];
-    }
-    return mp_obj_tuple_subscr(self_in, index, value);
-}
-
 void namedtuple_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
     if (dest[0] == MP_OBJ_NULL) {
         // load attribute
@@ -177,7 +168,7 @@ STATIC mp_obj_t mp_obj_new_namedtuple_type(qstr name, size_t n_fields, mp_obj_t
     o->base.unary_op = mp_obj_tuple_unary_op;
     o->base.binary_op = mp_obj_tuple_binary_op;
     o->base.attr = namedtuple_attr;
-    o->base.subscr = namedtuple_subscr;
+    o->base.subscr = mp_obj_tuple_subscr;
     o->base.getiter = mp_obj_tuple_getiter;
     o->base.parent = &mp_type_tuple;
     return MP_OBJ_FROM_PTR(o);
diff --git a/py/objnamedtuple.h b/py/objnamedtuple.h
index 5a7512e3a..0ea0d2862 100644
--- a/py/objnamedtuple.h
+++ b/py/objnamedtuple.h
@@ -49,7 +49,6 @@ typedef struct _mp_obj_namedtuple_t {
 
 void namedtuple_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind);
 size_t mp_obj_namedtuple_find_field(const mp_obj_namedtuple_type_t *type, qstr name);
-mp_obj_t namedtuple_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value);
 void namedtuple_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest);
 mp_obj_namedtuple_type_t *mp_obj_new_namedtuple_base(size_t n_fields, mp_obj_t *fields);
 mp_obj_t namedtuple_make_new(const mp_obj_type_t *type_in, size_t n_args, const mp_obj_t *args, mp_map_t *kw_args);
diff --git a/py/objtuple.c b/py/objtuple.c
index 2b483f8b8..0a2ed6f4c 100644
--- a/py/objtuple.c
+++ b/py/objtuple.c
@@ -29,6 +29,7 @@
 
 #include "py/objtuple.h"
 #include "py/runtime.h"
+#include "py/objtype.h"
 
 #include "supervisor/shared/translate.h"
 
@@ -178,10 +179,14 @@ mp_obj_t mp_obj_tuple_binary_op(mp_binary_op_t op, mp_obj_t lhs, mp_obj_t rhs) {
 }
 
 mp_obj_t mp_obj_tuple_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
-
     if (value == MP_OBJ_SENTINEL) {
         // load
         mp_obj_tuple_t *self = MP_OBJ_TO_PTR(self_in);
+        // when called with a native type (eg namedtuple) using mp_obj_tuple_subscr, get the native self
+        if (self->base.type->subscr != &mp_obj_tuple_subscr) {
+            self = mp_instance_cast_to_native_base(self_in, &mp_type_tuple);
+        }
+
 #if MICROPY_PY_BUILTINS_SLICE
         if (MP_OBJ_IS_TYPE(index, &mp_type_slice)) {
             mp_bound_slice_t slice;
diff --git a/py/py.mk b/py/py.mk
index 9031c009f..a73b47f37 100644
--- a/py/py.mk
+++ b/py/py.mk
@@ -304,12 +304,12 @@ FORCE:
 
 $(HEADER_BUILD)/mpversion.h: FORCE | $(HEADER_BUILD)
 	$(STEPECHO) "GEN $@"
-	$(Q)$(PYTHON) $(PY_SRC)/makeversionhdr.py $@
+	$(Q)$(PYTHON3) $(PY_SRC)/makeversionhdr.py $@
 
 # build a list of registered modules for py/objmodule.c.
 $(HEADER_BUILD)/moduledefs.h: $(SRC_QSTR) $(QSTR_GLOBAL_DEPENDENCIES) | $(HEADER_BUILD)/mpversion.h
 	@$(STEPECHO) "GEN $@"
-	$(Q)$(PYTHON) $(PY_SRC)/makemoduledefs.py --vpath="., $(TOP), $(USER_C_MODULES)" $(SRC_QSTR) > $@
+	$(Q)$(PYTHON3) $(PY_SRC)/makemoduledefs.py --vpath="., $(TOP), $(USER_C_MODULES)" $(SRC_QSTR) > $@
 
 SRC_QSTR += $(HEADER_BUILD)/moduledefs.h
 
diff --git a/py/vstr.c b/py/vstr.c
index 869b27805..91cd7f584 100644
--- a/py/vstr.c
+++ b/py/vstr.c
@@ -50,6 +50,9 @@ void vstr_init(vstr_t *vstr, size_t alloc) {
 // Init the vstr so it allocs exactly enough ram to hold a null-terminated
 // string of the given length, and set the length.
 void vstr_init_len(vstr_t *vstr, size_t len) {
+    if(len == SIZE_MAX) {
+        m_malloc_fail(len);
+    }
     vstr_init(vstr, len + 1);
     vstr->len = len;
 }
diff --git a/shared-bindings/os/__init__.c b/shared-bindings/os/__init__.c
index 55ebd6f59..c2b63bbce 100644
--- a/shared-bindings/os/__init__.c
+++ b/shared-bindings/os/__init__.c
@@ -33,6 +33,7 @@
 #include "lib/oofatfs/diskio.h"
 #include "py/mpstate.h"
 #include "py/obj.h"
+#include "py/objstr.h"
 #include "py/runtime.h"
 #include "shared-bindings/os/__init__.h"
 
@@ -195,11 +196,11 @@ MP_DEFINE_CONST_FUN_OBJ_0(os_sync_obj, os_sync);
 //|
 STATIC mp_obj_t os_urandom(mp_obj_t size_in) {
     mp_int_t size = mp_obj_get_int(size_in);
-    uint8_t tmp[size];
-    if (!common_hal_os_urandom(tmp, size)) {
+    mp_obj_str_t *result = MP_OBJ_TO_PTR(mp_obj_new_bytes_of_zeros(size));
+    if (!common_hal_os_urandom((uint8_t*) result->data, size)) {
         mp_raise_NotImplementedError(translate("No hardware random available"));
     }
-    return mp_obj_new_bytes(tmp, size);
+    return result;
 }
 MP_DEFINE_CONST_FUN_OBJ_1(os_urandom_obj, os_urandom);
 
diff --git a/tests/basics/subscr_tuple.py b/tests/basics/subscr_tuple.py
new file mode 100644
index 000000000..85d25366d
--- /dev/null
+++ b/tests/basics/subscr_tuple.py
@@ -0,0 +1,7 @@
+# subscripting a subclassed tuple
+class Foo(tuple):
+    pass
+
+foo = Foo((1,2))
+foo[0]
+