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

44 files changed, 159 insertions, 154 deletions

diff --git a/ports/atmel-samd/boards/hallowing_m4_express/board.c b/ports/atmel-samd/boards/hallowing_m4_express/board.c
index 5d1ef6d9b..6bb2a591f 100644
--- a/ports/atmel-samd/boards/hallowing_m4_express/board.c
+++ b/ports/atmel-samd/boards/hallowing_m4_express/board.c
@@ -49,7 +49,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PA01, &pin_PA00, mp_const_none);
+    common_hal_busio_spi_construct(spi, &pin_PA01, &pin_PA00, NULL);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/monster_m4sk/board.c b/ports/atmel-samd/boards/monster_m4sk/board.c
index 40141ca15..2377f4a9d 100644
--- a/ports/atmel-samd/boards/monster_m4sk/board.c
+++ b/ports/atmel-samd/boards/monster_m4sk/board.c
@@ -50,7 +50,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PA13, &pin_PA12, mp_const_none);
+    common_hal_busio_spi_construct(spi, &pin_PA13, &pin_PA12, NULL);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/openbook_m4/board.c b/ports/atmel-samd/boards/openbook_m4/board.c
index 85a588879..2d9b31647 100644
--- a/ports/atmel-samd/boards/openbook_m4/board.c
+++ b/ports/atmel-samd/boards/openbook_m4/board.c
@@ -55,7 +55,7 @@ uint8_t stop_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, mp_const_none);
+    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, NULL);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/pewpew_m4/board.c b/ports/atmel-samd/boards/pewpew_m4/board.c
index 1872d1876..5f5a01e48 100644
--- a/ports/atmel-samd/boards/pewpew_m4/board.c
+++ b/ports/atmel-samd/boards/pewpew_m4/board.c
@@ -97,7 +97,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PA13, &pin_PA15, mp_const_none);
+    common_hal_busio_spi_construct(spi, &pin_PA13, &pin_PA15, NULL);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/pybadge/board.c b/ports/atmel-samd/boards/pybadge/board.c
index 28e1aec13..bead06f3c 100644
--- a/ports/atmel-samd/boards/pybadge/board.c
+++ b/ports/atmel-samd/boards/pybadge/board.c
@@ -72,7 +72,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, mp_const_none);
+    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, NULL);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/pybadge_airlift/board.c b/ports/atmel-samd/boards/pybadge_airlift/board.c
index fbb4441f0..061f3d777 100644
--- a/ports/atmel-samd/boards/pybadge_airlift/board.c
+++ b/ports/atmel-samd/boards/pybadge_airlift/board.c
@@ -50,7 +50,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, mp_const_none);
+    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, NULL);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/pygamer/board.c b/ports/atmel-samd/boards/pygamer/board.c
index c052614db..70d4a05dc 100644
--- a/ports/atmel-samd/boards/pygamer/board.c
+++ b/ports/atmel-samd/boards/pygamer/board.c
@@ -72,7 +72,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, mp_const_none);
+    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, NULL);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/pygamer_advance/board.c b/ports/atmel-samd/boards/pygamer_advance/board.c
index a138c7e50..ff2da34a2 100644
--- a/ports/atmel-samd/boards/pygamer_advance/board.c
+++ b/ports/atmel-samd/boards/pygamer_advance/board.c
@@ -50,7 +50,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB12, mp_const_none);
+    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB12, NULL);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/winterbloom_sol/mpconfigboard.mk b/ports/atmel-samd/boards/winterbloom_sol/mpconfigboard.mk
index a0449d7bb..b1f916ec2 100644
--- a/ports/atmel-samd/boards/winterbloom_sol/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/winterbloom_sol/mpconfigboard.mk
@@ -6,6 +6,7 @@ USB_PID = 0x8062
 USB_PRODUCT = "Sol"
 USB_MANUFACTURER = "Winterbloom"
 USB_INTERFACE_NAME = "Sol"
+USB_DEVICES = "CDC,MSC,AUDIO"
 
 CHIP_VARIANT = SAMD51J20A
 CHIP_FAMILY = samd51
@@ -25,6 +26,7 @@ CIRCUITPY_I2CSLAVE = 0
 CIRCUITPY_NETWORK = 0
 CIRCUITPY_TOUCHIO = 0
 CIRCUITPY_PS2IO = 0
+CIRCUITPY_USB_HID = 0
 
 # Enable micropython.native
 CIRCUITPY_ENABLE_MPY_NATIVE = 1
diff --git a/ports/atmel-samd/common-hal/analogio/AnalogIn.c b/ports/atmel-samd/common-hal/analogio/AnalogIn.c
index fc11d5d19..2bd218cdd 100644
--- a/ports/atmel-samd/common-hal/analogio/AnalogIn.c
+++ b/ports/atmel-samd/common-hal/analogio/AnalogIn.c
@@ -73,7 +73,7 @@ void common_hal_analogio_analogin_construct(analogio_analogin_obj_t* self,
 }
 
 bool common_hal_analogio_analogin_deinited(analogio_analogin_obj_t *self) {
-    return self->pin == mp_const_none;
+    return self->pin == NULL;
 }
 
 void common_hal_analogio_analogin_deinit(analogio_analogin_obj_t *self) {
@@ -81,7 +81,7 @@ void common_hal_analogio_analogin_deinit(analogio_analogin_obj_t *self) {
         return;
     }
     reset_pin_number(self->pin->number);
-    self->pin = mp_const_none;
+    self->pin = NULL;
 }
 
 void analogin_reset() {
diff --git a/ports/atmel-samd/common-hal/audiobusio/I2SOut.c b/ports/atmel-samd/common-hal/audiobusio/I2SOut.c
index 05a6aaf7b..8f827e7fb 100644
--- a/ports/atmel-samd/common-hal/audiobusio/I2SOut.c
+++ b/ports/atmel-samd/common-hal/audiobusio/I2SOut.c
@@ -89,6 +89,7 @@ void i2sout_reset(void) {
     #endif
 }
 
+// Caller validates that pins are free.
 void common_hal_audiobusio_i2sout_construct(audiobusio_i2sout_obj_t* self,
         const mcu_pin_obj_t* bit_clock, const mcu_pin_obj_t* word_select,
         const mcu_pin_obj_t* data, bool left_justified) {
@@ -182,9 +183,6 @@ void common_hal_audiobusio_i2sout_construct(audiobusio_i2sout_obj_t* self,
     #ifdef SAMD21
     #define GPIO_I2S_FUNCTION GPIO_PIN_FUNCTION_G
     #endif
-    assert_pin_free(bit_clock);
-    assert_pin_free(word_select);
-    assert_pin_free(data);
 
     self->bit_clock = bit_clock;
     self->word_select = word_select;
@@ -204,7 +202,7 @@ void common_hal_audiobusio_i2sout_construct(audiobusio_i2sout_obj_t* self,
 }
 
 bool common_hal_audiobusio_i2sout_deinited(audiobusio_i2sout_obj_t* self) {
-    return self->bit_clock == mp_const_none;
+    return self->bit_clock == NULL;
 }
 
 void common_hal_audiobusio_i2sout_deinit(audiobusio_i2sout_obj_t* self) {
@@ -213,11 +211,11 @@ void common_hal_audiobusio_i2sout_deinit(audiobusio_i2sout_obj_t* self) {
     }
 
     reset_pin_number(self->bit_clock->number);
-    self->bit_clock = mp_const_none;
+    self->bit_clock = NULL;
     reset_pin_number(self->word_select->number);
-    self->word_select = mp_const_none;
+    self->word_select = NULL;
     reset_pin_number(self->data->number);
-    self->data = mp_const_none;
+    self->data = NULL;
 }
 
 void common_hal_audiobusio_i2sout_play(audiobusio_i2sout_obj_t* self,
diff --git a/ports/atmel-samd/common-hal/audiobusio/PDMIn.c b/ports/atmel-samd/common-hal/audiobusio/PDMIn.c
index 3a51cce8f..76e66ab45 100644
--- a/ports/atmel-samd/common-hal/audiobusio/PDMIn.c
+++ b/ports/atmel-samd/common-hal/audiobusio/PDMIn.c
@@ -74,6 +74,7 @@ void pdmin_reset(void) {
     I2S->CTRLA.reg = I2S_CTRLA_SWRST;
 }
 
+// Caller validates that pins are free.
 void common_hal_audiobusio_pdmin_construct(audiobusio_pdmin_obj_t* self,
                                            const mcu_pin_obj_t* clock_pin,
                                            const mcu_pin_obj_t* data_pin,
@@ -157,8 +158,6 @@ void common_hal_audiobusio_pdmin_construct(audiobusio_pdmin_obj_t* self,
     #ifdef SAMD21
     #define GPIO_I2S_FUNCTION GPIO_PIN_FUNCTION_G
     #endif
-    assert_pin_free(clock_pin);
-    assert_pin_free(data_pin);
 
     uint32_t clock_divisor = (uint32_t) roundf( 48000000.0f / sample_rate / oversample);
     float mic_clock_freq = 48000000.0f / clock_divisor;
@@ -219,7 +218,7 @@ void common_hal_audiobusio_pdmin_construct(audiobusio_pdmin_obj_t* self,
 }
 
 bool common_hal_audiobusio_pdmin_deinited(audiobusio_pdmin_obj_t* self) {
-    return self->clock_pin == mp_const_none;
+    return self->clock_pin == NULL;
 }
 
 void common_hal_audiobusio_pdmin_deinit(audiobusio_pdmin_obj_t* self) {
@@ -237,8 +236,8 @@ void common_hal_audiobusio_pdmin_deinit(audiobusio_pdmin_obj_t* self) {
 
     reset_pin_number(self->clock_pin->number);
     reset_pin_number(self->data_pin->number);
-    self->clock_pin = mp_const_none;
-    self->data_pin = mp_const_none;
+    self->clock_pin = NULL;
+    self->data_pin = NULL;
 }
 
 uint8_t common_hal_audiobusio_pdmin_get_bit_depth(audiobusio_pdmin_obj_t* self) {
diff --git a/ports/atmel-samd/common-hal/audioio/AudioOut.c b/ports/atmel-samd/common-hal/audioio/AudioOut.c
index b75c2b335..75621b361 100644
--- a/ports/atmel-samd/common-hal/audioio/AudioOut.c
+++ b/ports/atmel-samd/common-hal/audioio/AudioOut.c
@@ -115,6 +115,7 @@ void audioout_reset(void) {
     // TODO(tannewt): Turn off the DAC clocks to save power.
 }
 
+// Caller validates that pins are free.
 void common_hal_audioio_audioout_construct(audioio_audioout_obj_t* self,
         const mcu_pin_obj_t* left_channel, const mcu_pin_obj_t* right_channel, uint16_t quiescent_value) {
     #ifdef SAMD51
@@ -135,7 +136,6 @@ void common_hal_audioio_audioout_construct(audioio_audioout_obj_t* self,
     if (left_channel != &pin_PA02) {
         mp_raise_ValueError(translate("Invalid pin"));
     }
-    assert_pin_free(left_channel);
     claim_pin(left_channel);
     #endif
     #ifdef SAMD51
@@ -143,7 +143,6 @@ void common_hal_audioio_audioout_construct(audioio_audioout_obj_t* self,
     if (left_channel != &pin_PA02 && left_channel != &pin_PA05) {
         mp_raise_ValueError(translate("Invalid pin for left channel"));
     }
-    assert_pin_free(left_channel);
     if (right_channel != NULL && right_channel != &pin_PA02 && right_channel != &pin_PA05) {
         mp_raise_ValueError(translate("Invalid pin for right channel"));
     }
@@ -304,7 +303,7 @@ void common_hal_audioio_audioout_construct(audioio_audioout_obj_t* self,
 }
 
 bool common_hal_audioio_audioout_deinited(audioio_audioout_obj_t* self) {
-    return self->left_channel == mp_const_none;
+    return self->left_channel == NULL;
 }
 
 void common_hal_audioio_audioout_deinit(audioio_audioout_obj_t* self) {
@@ -332,10 +331,10 @@ void common_hal_audioio_audioout_deinit(audioio_audioout_obj_t* self) {
     tc_set_enable(tc_insts[self->tc_index], false);
 
     reset_pin_number(self->left_channel->number);
-    self->left_channel = mp_const_none;
+    self->left_channel = NULL;
     #ifdef SAMD51
     reset_pin_number(self->right_channel->number);
-    self->right_channel = mp_const_none;
+    self->right_channel = NULL;
     #endif
 }
 
diff --git a/ports/atmel-samd/common-hal/busio/SPI.c b/ports/atmel-samd/common-hal/busio/SPI.c
index 7a1426bed..1dc389027 100644
--- a/ports/atmel-samd/common-hal/busio/SPI.c
+++ b/ports/atmel-samd/common-hal/busio/SPI.c
@@ -89,8 +89,8 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
     Sercom* sercom = NULL;
     uint8_t sercom_index;
     uint32_t clock_pinmux = 0;
-    bool mosi_none = mosi == mp_const_none || mosi == NULL;
-    bool miso_none = miso == mp_const_none || miso == NULL;
+    bool mosi_none = mosi == NULL;
+    bool miso_none = miso == NULL;
     uint32_t mosi_pinmux = 0;
     uint32_t miso_pinmux = 0;
     uint8_t clock_pad = 0;
diff --git a/ports/atmel-samd/common-hal/busio/UART.c b/ports/atmel-samd/common-hal/busio/UART.c
index fb9968605..1f6b75f97 100644
--- a/ports/atmel-samd/common-hal/busio/UART.c
+++ b/ports/atmel-samd/common-hal/busio/UART.c
@@ -65,7 +65,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     uint32_t tx_pinmux = 0;
     uint8_t tx_pad = 255; // Unset pad
 
-    if ((rts != mp_const_none) || (cts != mp_const_none) || (rs485_dir != mp_const_none) || (rs485_invert)) {
+    if ((rts != NULL) || (cts != NULL) || (rs485_dir != NULL) || (rs485_invert)) {
         mp_raise_ValueError(translate("RTS/CTS/RS485 Not yet supported on this device"));
     }
 
@@ -73,8 +73,8 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
         mp_raise_NotImplementedError(translate("bytes > 8 bits not supported"));
     }
 
-    bool have_tx = tx != mp_const_none;
-    bool have_rx = rx != mp_const_none;
+    bool have_tx = tx != NULL;
+    bool have_rx = rx != NULL;
     if (!have_tx && !have_rx) {
         mp_raise_ValueError(translate("tx and rx cannot both be None"));
     }
@@ -109,7 +109,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
 #endif
             tx_pinmux = PINMUX(tx->number, (i == 0) ? MUX_C : MUX_D);
             tx_pad = tx->sercom[i].pad;
-            if (rx == mp_const_none) {
+            if (rx == NULL) {
                 sercom = potential_sercom;
                 break;
             }
diff --git a/ports/atmel-samd/common-hal/digitalio/DigitalInOut.c b/ports/atmel-samd/common-hal/digitalio/DigitalInOut.c
index e167cbb69..68d3da806 100644
--- a/ports/atmel-samd/common-hal/digitalio/DigitalInOut.c
+++ b/ports/atmel-samd/common-hal/digitalio/DigitalInOut.c
@@ -55,7 +55,7 @@ void common_hal_digitalio_digitalinout_never_reset(
 }
 
 bool common_hal_digitalio_digitalinout_deinited(digitalio_digitalinout_obj_t* self) {
-    return self->pin == mp_const_none;
+    return self->pin == NULL;
 }
 
 void common_hal_digitalio_digitalinout_deinit(digitalio_digitalinout_obj_t* self) {
@@ -63,7 +63,7 @@ void common_hal_digitalio_digitalinout_deinit(digitalio_digitalinout_obj_t* self
         return;
     }
     reset_pin_number(self->pin->number);
-    self->pin = mp_const_none;
+    self->pin = NULL;
 }
 
 void common_hal_digitalio_digitalinout_switch_to_input(
diff --git a/ports/atmel-samd/common-hal/pulseio/PWMOut.c b/ports/atmel-samd/common-hal/pulseio/PWMOut.c
index 0adb23fc5..fef581584 100644
--- a/ports/atmel-samd/common-hal/pulseio/PWMOut.c
+++ b/ports/atmel-samd/common-hal/pulseio/PWMOut.c
@@ -292,7 +292,7 @@ pwmout_result_t common_hal_pulseio_pwmout_construct(pulseio_pwmout_obj_t* self,
 }
 
 bool common_hal_pulseio_pwmout_deinited(pulseio_pwmout_obj_t* self) {
-    return self->pin == mp_const_none;
+    return self->pin == NULL;
 }
 
 void common_hal_pulseio_pwmout_deinit(pulseio_pwmout_obj_t* self) {
@@ -319,7 +319,7 @@ void common_hal_pulseio_pwmout_deinit(pulseio_pwmout_obj_t* self) {
         }
     }
     reset_pin_number(self->pin->number);
-    self->pin = mp_const_none;
+    self->pin = NULL;
 }
 
 extern void common_hal_pulseio_pwmout_set_duty_cycle(pulseio_pwmout_obj_t* self, uint16_t duty) {
diff --git a/ports/atmel-samd/mpconfigport.mk b/ports/atmel-samd/mpconfigport.mk
index 7565e41a4..6b6b335d3 100644
--- a/ports/atmel-samd/mpconfigport.mk
+++ b/ports/atmel-samd/mpconfigport.mk
@@ -40,6 +40,8 @@ endif
 # SAMD21 needs separate endpoint pairs for MSC BULK IN and BULK OUT, otherwise it's erratic.
 USB_MSC_EP_NUM_OUT = 1
 
+MICROPY_PY_ULAB = 0
+
 endif # samd21
 
 # Put samd51-only choices here.
diff --git a/ports/cxd56/Makefile b/ports/cxd56/Makefile
index a0782c4e9..e2fce976d 100644
--- a/ports/cxd56/Makefile
+++ b/ports/cxd56/Makefile
@@ -176,6 +176,10 @@ OBJ = $(PY_O) $(SUPERVISOR_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_S:.s=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_COMMON_HAL_EXPANDED:.c=.o))
 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_MOD:.c=.o))
 
 # List of sources for qstr extraction
 SRC_QSTR += $(SRC_C) $(SRC_SUPERVISOR) $(SRC_COMMON_HAL_EXPANDED) $(SRC_SHARED_MODULE_EXPANDED)
diff --git a/ports/cxd56/common-hal/analogio/AnalogIn.c b/ports/cxd56/common-hal/analogio/AnalogIn.c
index e2ca5e4a4..cdf37c06a 100644
--- a/ports/cxd56/common-hal/analogio/AnalogIn.c
+++ b/ports/cxd56/common-hal/analogio/AnalogIn.c
@@ -83,7 +83,7 @@ void common_hal_analogio_analogin_construct(analogio_analogin_obj_t *self, const
 
     // start ADC
     ioctl(analogin_dev[self->number].fd, ANIOC_CXD56_START, 0);
-    
+
     self->pin = pin;
 }
 
@@ -97,7 +97,7 @@ void common_hal_analogio_analogin_deinit(analogio_analogin_obj_t *self) {
     close(analogin_dev[self->number].fd);
     analogin_dev[self->number].fd = -1;
 
-    self->pin = mp_const_none;
+    self->pin = NULL;
 }
 
 bool common_hal_analogio_analogin_deinited(analogio_analogin_obj_t *self) {
diff --git a/ports/cxd56/common-hal/busio/UART.c b/ports/cxd56/common-hal/busio/UART.c
index 3ed980952..3bca240e0 100644
--- a/ports/cxd56/common-hal/busio/UART.c
+++ b/ports/cxd56/common-hal/busio/UART.c
@@ -60,10 +60,10 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     mp_float_t timeout, uint16_t receiver_buffer_size) {
     struct termios tio;
 
-    if ((rts != mp_const_none) || (cts != mp_const_none) || (rs485_dir != mp_const_none) || (rs485_invert)) {
+    if ((rts != NULL) || (cts != NULL) || (rs485_dir != NULL) || (rs485_invert)) {
         mp_raise_ValueError(translate("RTS/CTS/RS485 Not yet supported on this device"));
     }
-    
+
     if (bits != 8) {
         mp_raise_ValueError(translate("Could not initialize UART"));
     }
diff --git a/ports/cxd56/common-hal/digitalio/DigitalInOut.c b/ports/cxd56/common-hal/digitalio/DigitalInOut.c
index 7b1f6cc03..c9af12e44 100644
--- a/ports/cxd56/common-hal/digitalio/DigitalInOut.c
+++ b/ports/cxd56/common-hal/digitalio/DigitalInOut.c
@@ -56,11 +56,11 @@ void common_hal_digitalio_digitalinout_deinit(digitalio_digitalinout_obj_t *self
     board_gpio_config(self->pin->number, 0, false, true, PIN_FLOAT);
 
     reset_pin_number(self->pin->number);
-    self->pin = mp_const_none;
+    self->pin = NULL;
 }
 
 bool common_hal_digitalio_digitalinout_deinited(digitalio_digitalinout_obj_t *self) {
-    return self->pin == mp_const_none;
+    return self->pin == NULL;
 }
 
 void common_hal_digitalio_digitalinout_switch_to_input(digitalio_digitalinout_obj_t *self, digitalio_pull_t pull) {
diff --git a/ports/cxd56/common-hal/pulseio/PWMOut.c b/ports/cxd56/common-hal/pulseio/PWMOut.c
index a0b4e79c6..7e0be566b 100644
--- a/ports/cxd56/common-hal/pulseio/PWMOut.c
+++ b/ports/cxd56/common-hal/pulseio/PWMOut.c
@@ -50,7 +50,7 @@ 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) {
     self->number = -1;
-    
+
     for (int i = 0; i < MP_ARRAY_SIZE(pwmout_dev); i++) {
         if (pin->number == pwmout_dev[i].pin->number) {
             self->number = i;
@@ -95,7 +95,7 @@ void common_hal_pulseio_pwmout_deinit(pulseio_pwmout_obj_t *self) {
     pwmout_dev[self->number].fd = -1;
 
     reset_pin_number(self->pin->number);
-    self->pin = mp_const_none;
+    self->pin = NULL;
 }
 
 bool common_hal_pulseio_pwmout_deinited(pulseio_pwmout_obj_t *self) {
@@ -131,11 +131,11 @@ bool common_hal_pulseio_pwmout_get_variable_frequency(pulseio_pwmout_obj_t *self
 void common_hal_pulseio_pwmout_never_reset(pulseio_pwmout_obj_t *self) {
     never_reset_pin_number(self->pin->number);
 
-    pwmout_dev[self->number].reset = false;    
+    pwmout_dev[self->number].reset = false;
 }
 
 void common_hal_pulseio_pwmout_reset_ok(pulseio_pwmout_obj_t *self) {
-    pwmout_dev[self->number].reset = true; 
+    pwmout_dev[self->number].reset = true;
 }
 
 void pwmout_reset(void) {
diff --git a/ports/cxd56/common-hal/pulseio/PulseIn.c b/ports/cxd56/common-hal/pulseio/PulseIn.c
index dd2773d1d..65ca1d97e 100644
--- a/ports/cxd56/common-hal/pulseio/PulseIn.c
+++ b/ports/cxd56/common-hal/pulseio/PulseIn.c
@@ -106,7 +106,7 @@ void common_hal_pulseio_pulsein_construct(pulseio_pulsein_obj_t *self,
 
     board_gpio_int(self->pin->number, true);
 }
-    
+
 void common_hal_pulseio_pulsein_deinit(pulseio_pulsein_obj_t *self) {
     if (common_hal_pulseio_pulsein_deinited(self)) {
         return;
@@ -116,18 +116,18 @@ void common_hal_pulseio_pulsein_deinit(pulseio_pulsein_obj_t *self) {
     board_gpio_intconfig(self->pin->number, 0, false, NULL);
 
     reset_pin_number(self->pin->number);
-    self->pin = mp_const_none;
+    self->pin = NULL;
 }
- 
+
 bool common_hal_pulseio_pulsein_deinited(pulseio_pulsein_obj_t *self) {
-    return self->pin == mp_const_none;
+    return self->pin == NULL;
 }
- 
+
 void common_hal_pulseio_pulsein_pause(pulseio_pulsein_obj_t *self) {
     board_gpio_int(self->pin->number, false);
     self->paused = true;
 }
- 
+
 void common_hal_pulseio_pulsein_resume(pulseio_pulsein_obj_t *self, uint16_t trigger_duration) {
     // Make sure we're paused.
     common_hal_pulseio_pulsein_pause(self);
@@ -147,14 +147,14 @@ void common_hal_pulseio_pulsein_resume(pulseio_pulsein_obj_t *self, uint16_t tri
     pulsein_set_config(self, true);
     board_gpio_int(self->pin->number, true);
 }
- 
+
 void common_hal_pulseio_pulsein_clear(pulseio_pulsein_obj_t *self) {
     common_hal_mcu_disable_interrupts();
     self->start = 0;
     self->len = 0;
     common_hal_mcu_enable_interrupts();
 }
- 
+
 uint16_t common_hal_pulseio_pulsein_popleft(pulseio_pulsein_obj_t *self) {
     if (self->len == 0) {
         mp_raise_IndexError(translate("pop from an empty PulseIn"));
@@ -167,19 +167,19 @@ uint16_t common_hal_pulseio_pulsein_popleft(pulseio_pulsein_obj_t *self) {
 
     return value;
 }
- 
+
 uint16_t common_hal_pulseio_pulsein_get_maxlen(pulseio_pulsein_obj_t *self) {
     return self->maxlen;
 }
- 
+
 bool common_hal_pulseio_pulsein_get_paused(pulseio_pulsein_obj_t *self) {
     return self->paused;
 }
- 
+
 uint16_t common_hal_pulseio_pulsein_get_len(pulseio_pulsein_obj_t *self) {
     return self->len;
 }
- 
+
 uint16_t common_hal_pulseio_pulsein_get_item(pulseio_pulsein_obj_t *self, int16_t index) {
     common_hal_mcu_disable_interrupts();
     if (index < 0) {
@@ -193,4 +193,3 @@ uint16_t common_hal_pulseio_pulsein_get_item(pulseio_pulsein_obj_t *self, int16_
     common_hal_mcu_enable_interrupts();
     return value;
 }
- 
\ No newline at end of file
diff --git a/ports/cxd56/mpconfigport.mk b/ports/cxd56/mpconfigport.mk
index a418ae8e9..ad3d0e72d 100644
--- a/ports/cxd56/mpconfigport.mk
+++ b/ports/cxd56/mpconfigport.mk
@@ -18,3 +18,5 @@ CIRCUITPY_NEOPIXEL_WRITE = 0
 CIRCUITPY_NVM = 0
 CIRCUITPY_DISPLAYIO = 0
 CIRCUITPY_FREQUENCYIO = 0
+
+INTERNAL_LIBM = 1
diff --git a/ports/mimxrt10xx/common-hal/analogio/AnalogIn.c b/ports/mimxrt10xx/common-hal/analogio/AnalogIn.c
index d714001f3..2cc2681b4 100644
--- a/ports/mimxrt10xx/common-hal/analogio/AnalogIn.c
+++ b/ports/mimxrt10xx/common-hal/analogio/AnalogIn.c
@@ -58,7 +58,7 @@ void common_hal_analogio_analogin_construct(analogio_analogin_obj_t* self,
 }
 
 bool common_hal_analogio_analogin_deinited(analogio_analogin_obj_t *self) {
-    return self->pin == mp_const_none;
+    return self->pin == NULL;
 }
 
 void common_hal_analogio_analogin_deinit(analogio_analogin_obj_t *self) {
@@ -66,7 +66,7 @@ void common_hal_analogio_analogin_deinit(analogio_analogin_obj_t *self) {
         return;
     }
     reset_pin_number(self->pin->number);
-    self->pin = mp_const_none;
+    self->pin = NULL;
 }
 
 uint16_t common_hal_analogio_analogin_get_value(analogio_analogin_obj_t *self) {
diff --git a/ports/mimxrt10xx/common-hal/busio/UART.c b/ports/mimxrt10xx/common-hal/busio/UART.c
index 4fd7afecb..b34b948b2 100644
--- a/ports/mimxrt10xx/common-hal/busio/UART.c
+++ b/ports/mimxrt10xx/common-hal/busio/UART.c
@@ -80,8 +80,8 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
 
     // TODO: Allow none rx or tx
 
-    bool have_tx = tx != mp_const_none;
-    bool have_rx = rx != mp_const_none;
+    bool have_tx = tx != NULL;
+    bool have_rx = rx != NULL;
     if (!have_tx && !have_rx) {
         mp_raise_ValueError(translate("tx and rx cannot both be None"));
     }
@@ -116,8 +116,8 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     }
 
     // Filter for sane settings for RS485
-    if (rs485_dir != mp_const_none) {
-      if ((rts != mp_const_none) || (cts != mp_const_none)) {
+    if (rs485_dir != NULL) {
+      if ((rts != NULL) || (cts != NULL)) {
         mp_raise_ValueError(translate("Cannot specify RTS or CTS in RS485 mode"));
       }
       // For IMXRT the RTS pin is used for RS485 direction
@@ -133,7 +133,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     const uint32_t rts_count = sizeof(mcu_uart_rts_list) / sizeof(mcu_periph_obj_t);
     const uint32_t cts_count = sizeof(mcu_uart_cts_list) / sizeof(mcu_periph_obj_t);
 
-    if (rts != mp_const_none) {
+    if (rts != NULL) {
       for (uint32_t i=0; i < rts_count; ++i) {
         if (mcu_uart_rts_list[i].bank_idx == self->rx_pin->bank_idx) {
           if (mcu_uart_rts_list[i].pin == rts) {
@@ -146,7 +146,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
         mp_raise_ValueError(translate("Selected RTS pin not valid"));
     }
 
-    if (cts != mp_const_none) {
+    if (cts != NULL) {
       for (uint32_t i=0; i < cts_count; ++i) {
         if (mcu_uart_cts_list[i].bank_idx == self->rx_pin->bank_idx) {
           if (mcu_uart_cts_list[i].pin == cts) {
@@ -158,7 +158,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
       if (self->cts_pin == NULL)
         mp_raise_ValueError(translate("Selected CTS pin not valid"));
     }
-    
+
     self->uart = mcu_uart_banks[self->tx_pin->bank_idx - 1];
 
     config_periph_pin(self->rx_pin);
@@ -166,7 +166,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     if (self->rts_pin)
       config_periph_pin(self->rts_pin);
     if (self->cts_pin)
-      config_periph_pin(self->cts_pin);    
+      config_periph_pin(self->cts_pin);
 
     lpuart_config_t config = { 0 };
     LPUART_GetDefaultConfig(&config);
@@ -187,7 +187,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     // Before we init, setup RS485 direction pin
     // ..unfortunately this isn't done by the driver library
     uint32_t modir = (self->uart->MODIR) & ~(LPUART_MODIR_TXRTSPOL_MASK | LPUART_MODIR_TXRTSE_MASK);
-    if (rs485_dir != mp_const_none) {
+    if (rs485_dir != NULL) {
       modir |= LPUART_MODIR_TXRTSE_MASK;
       if (rs485_invert)
         modir |= LPUART_MODIR_TXRTSPOL_MASK;
diff --git a/ports/mimxrt10xx/common-hal/digitalio/DigitalInOut.c b/ports/mimxrt10xx/common-hal/digitalio/DigitalInOut.c
index d69a18d96..603515764 100644
--- a/ports/mimxrt10xx/common-hal/digitalio/DigitalInOut.c
+++ b/ports/mimxrt10xx/common-hal/digitalio/DigitalInOut.c
@@ -78,7 +78,7 @@ void common_hal_digitalio_digitalinout_never_reset(
 }
 
 bool common_hal_digitalio_digitalinout_deinited(digitalio_digitalinout_obj_t* self) {
-    return self->pin == mp_const_none;
+    return self->pin == NULL;
 }
 
 void common_hal_digitalio_digitalinout_deinit(digitalio_digitalinout_obj_t* self) {
@@ -86,7 +86,7 @@ void common_hal_digitalio_digitalinout_deinit(digitalio_digitalinout_obj_t* self
         return;
     }
     reset_pin_number(self->pin->number);
-    self->pin = mp_const_none;
+    self->pin = NULL;
 }
 
 void common_hal_digitalio_digitalinout_switch_to_input(
diff --git a/ports/nrf/boards/clue_nrf52840_express/board.c b/ports/nrf/boards/clue_nrf52840_express/board.c
index 5f5337a3d..e342c6d93 100644
--- a/ports/nrf/boards/clue_nrf52840_express/board.c
+++ b/ports/nrf/boards/clue_nrf52840_express/board.c
@@ -49,7 +49,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_P0_14, &pin_P0_15, mp_const_none);
+    common_hal_busio_spi_construct(spi, &pin_P0_14, &pin_P0_15, NULL);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/nrf/boards/ohs2020_badge/board.c b/ports/nrf/boards/ohs2020_badge/board.c
index 7e3e05814..9e881d763 100644
--- a/ports/nrf/boards/ohs2020_badge/board.c
+++ b/ports/nrf/boards/ohs2020_badge/board.c
@@ -49,7 +49,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_P0_11, &pin_P0_12, mp_const_none);
+    common_hal_busio_spi_construct(spi, &pin_P0_11, &pin_P0_12, NULL);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/nrf/common-hal/analogio/AnalogIn.c b/ports/nrf/common-hal/analogio/AnalogIn.c
index 3bc097019..dbcc5281c 100644
--- a/ports/nrf/common-hal/analogio/AnalogIn.c
+++ b/ports/nrf/common-hal/analogio/AnalogIn.c
@@ -55,7 +55,7 @@ void common_hal_analogio_analogin_construct(analogio_analogin_obj_t *self, const
 }
 
 bool common_hal_analogio_analogin_deinited(analogio_analogin_obj_t *self) {
-    return self->pin == mp_const_none;
+    return self->pin == NULL;
 }
 
 void common_hal_analogio_analogin_deinit(analogio_analogin_obj_t *self) {
@@ -65,7 +65,7 @@ void common_hal_analogio_analogin_deinit(analogio_analogin_obj_t *self) {
     nrf_gpio_cfg_default(self->pin->number);
 
     reset_pin_number(self->pin->number);
-    self->pin = mp_const_none;
+    self->pin = NULL;
 }
 
 uint16_t common_hal_analogio_analogin_get_value(analogio_analogin_obj_t *self) {
diff --git a/ports/nrf/common-hal/audiobusio/PDMIn.c b/ports/nrf/common-hal/audiobusio/PDMIn.c
index a7f9c9d74..ddd34174b 100644
--- a/ports/nrf/common-hal/audiobusio/PDMIn.c
+++ b/ports/nrf/common-hal/audiobusio/PDMIn.c
@@ -34,6 +34,7 @@ NRF_PDM_Type *nrf_pdm = NRF_PDM;
 
 static uint32_t dummy_buffer[4];
 
+// Caller validates that pins are free.
 void common_hal_audiobusio_pdmin_construct(audiobusio_pdmin_obj_t* self,
                                            const mcu_pin_obj_t* clock_pin,
                                            const mcu_pin_obj_t* data_pin,
@@ -41,8 +42,6 @@ void common_hal_audiobusio_pdmin_construct(audiobusio_pdmin_obj_t* self,
                                            uint8_t bit_depth,
                                            bool mono,
                                            uint8_t oversample) {
-    assert_pin_free(clock_pin);
-    assert_pin_free(data_pin);
     claim_pin(clock_pin);
     claim_pin(data_pin);
 
diff --git a/ports/nrf/common-hal/audiopwmio/PWMAudioOut.c b/ports/nrf/common-hal/audiopwmio/PWMAudioOut.c
index cdb57bbe1..7b99901d5 100644
--- a/ports/nrf/common-hal/audiopwmio/PWMAudioOut.c
+++ b/ports/nrf/common-hal/audiopwmio/PWMAudioOut.c
@@ -155,10 +155,9 @@ void audiopwmout_background() {
     }
 }
 
+// Caller validates that pins are free.
 void common_hal_audiopwmio_pwmaudioout_construct(audiopwmio_pwmaudioout_obj_t* self,
         const mcu_pin_obj_t* left_channel, const mcu_pin_obj_t* right_channel, uint16_t quiescent_value) {
-    assert_pin_free(left_channel);
-    assert_pin_free(right_channel);
     self->pwm = pwmout_allocate(256, PWM_PRESCALER_PRESCALER_DIV_1, true, NULL, NULL);
     if (!self->pwm) {
         mp_raise_RuntimeError(translate("All timers in use"));
diff --git a/ports/nrf/common-hal/busio/SPI.c b/ports/nrf/common-hal/busio/SPI.c
index b4ebddde1..3f205e778 100644
--- a/ports/nrf/common-hal/busio/SPI.c
+++ b/ports/nrf/common-hal/busio/SPI.c
@@ -155,7 +155,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self, const mcu_pin_obj_t *
     self->clock_pin_number = clock->number;
     claim_pin(clock);
 
-    if (mosi != mp_const_none) {
+    if (mosi != NULL) {
         config.mosi_pin = mosi->number;
         self->MOSI_pin_number = mosi->number;
         claim_pin(mosi);
@@ -163,7 +163,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self, const mcu_pin_obj_t *
         self->MOSI_pin_number = NO_PIN;
     }
 
-    if (miso != mp_const_none) {
+    if (miso != NULL) {
         config.miso_pin = miso->number;
         self->MISO_pin_number = mosi->number;
         claim_pin(miso);
diff --git a/ports/nrf/common-hal/busio/UART.c b/ports/nrf/common-hal/busio/UART.c
index 933faf17b..14fa36374 100644
--- a/ports/nrf/common-hal/busio/UART.c
+++ b/ports/nrf/common-hal/busio/UART.c
@@ -135,10 +135,10 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     uint32_t baudrate, uint8_t bits, uart_parity_t parity, uint8_t stop,
     mp_float_t timeout, uint16_t receiver_buffer_size) {
 
-    if ((rts != mp_const_none) || (cts != mp_const_none) || (rs485_dir != mp_const_none) || (rs485_invert)) {
+    if ((rts != NULL) || (cts != NULL) || (rs485_dir != NULL) || (rs485_invert)) {
         mp_raise_ValueError(translate("RTS/CTS/RS485 Not yet supported on this device"));
     }
-  
+
     // Find a free UART peripheral.
     self->uarte = NULL;
     for (size_t i = 0 ; i < MP_ARRAY_SIZE(nrfx_uartes); i++) {
@@ -152,7 +152,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
         mp_raise_ValueError(translate("All UART peripherals are in use"));
     }
 
-    if ( (tx == mp_const_none) && (rx == mp_const_none) ) {
+    if ( (tx == NULL) && (rx == NULL) ) {
         mp_raise_ValueError(translate("tx and rx cannot both be None"));
     }
 
@@ -165,8 +165,8 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     }
 
     nrfx_uarte_config_t config = {
-        .pseltxd = (tx == mp_const_none) ? NRF_UARTE_PSEL_DISCONNECTED : tx->number,
-        .pselrxd = (rx == mp_const_none) ? NRF_UARTE_PSEL_DISCONNECTED : rx->number,
+        .pseltxd = (tx == NULL) ? NRF_UARTE_PSEL_DISCONNECTED : tx->number,
+        .pselrxd = (rx == NULL) ? NRF_UARTE_PSEL_DISCONNECTED : rx->number,
         .pselcts = NRF_UARTE_PSEL_DISCONNECTED,
         .pselrts = NRF_UARTE_PSEL_DISCONNECTED,
         .p_context = self,
@@ -181,7 +181,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     _VERIFY_ERR(nrfx_uarte_init(self->uarte, &config, uart_callback_irq));
 
     // Init buffer for rx
-    if ( rx != mp_const_none ) {
+    if ( rx != NULL ) {
         // Initially allocate the UART's buffer in the long-lived part of the
         // heap.  UARTs are generally long-lived objects, but the "make long-
         // lived" machinery is incapable of moving internal pointers like
@@ -200,7 +200,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
         claim_pin(rx);
     }
 
-    if ( tx != mp_const_none ) {
+    if ( tx != NULL ) {
         self->tx_pin_number = tx->number;
         claim_pin(tx);
     } else {
diff --git a/ports/nrf/common-hal/digitalio/DigitalInOut.c b/ports/nrf/common-hal/digitalio/DigitalInOut.c
index 0836962c6..c5a7a7dfb 100644
--- a/ports/nrf/common-hal/digitalio/DigitalInOut.c
+++ b/ports/nrf/common-hal/digitalio/DigitalInOut.c
@@ -46,7 +46,7 @@ digitalinout_result_t common_hal_digitalio_digitalinout_construct(
 }
 
 bool common_hal_digitalio_digitalinout_deinited(digitalio_digitalinout_obj_t *self) {
-    return self->pin == mp_const_none;
+    return self->pin == NULL;
 }
 
 void common_hal_digitalio_digitalinout_deinit(digitalio_digitalinout_obj_t *self) {
@@ -56,7 +56,7 @@ void common_hal_digitalio_digitalinout_deinit(digitalio_digitalinout_obj_t *self
     nrf_gpio_cfg_default(self->pin->number);
 
     reset_pin_number(self->pin->number);
-    self->pin = mp_const_none;
+    self->pin = NULL;
 }
 
 void common_hal_digitalio_digitalinout_switch_to_input(
diff --git a/ports/stm32f4/common-hal/analogio/AnalogIn.c b/ports/stm32f4/common-hal/analogio/AnalogIn.c
index 3ee3c4dbb..1d1b308b6 100644
--- a/ports/stm32f4/common-hal/analogio/AnalogIn.c
+++ b/ports/stm32f4/common-hal/analogio/AnalogIn.c
@@ -45,11 +45,11 @@ void common_hal_analogio_analogin_construct(analogio_analogin_obj_t* self,
     }
     // TODO: add ADC traits to structure?
 
-    // Note that ADC2 is always bundled pin-to-pin with ADC1 if it exists, and used only 
-    // for dual conversion. For this basic application it is never used. 
+    // Note that ADC2 is always bundled pin-to-pin with ADC1 if it exists, and used only
+    // for dual conversion. For this basic application it is never used.
     LL_GPIO_SetPinMode(pin_port(pin->port), (uint32_t)pin_mask(pin->number), LL_GPIO_MODE_ANALOG);
     if (pin->adc_unit & 0x01) {
-        LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_ADC1); 
+        LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_ADC1);
     } else if (pin->adc_unit == 0x04) {
         #ifdef LL_APB2_GRP1_PERIPH_ADC3
         LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_ADC3);
@@ -62,7 +62,7 @@ void common_hal_analogio_analogin_construct(analogio_analogin_obj_t* self,
 }
 
 bool common_hal_analogio_analogin_deinited(analogio_analogin_obj_t *self) {
-    return self->pin == mp_const_none;
+    return self->pin == NULL;
 }
 
 void common_hal_analogio_analogin_deinit(analogio_analogin_obj_t *self) {
@@ -70,7 +70,7 @@ void common_hal_analogio_analogin_deinit(analogio_analogin_obj_t *self) {
         return;
     }
     reset_pin_number(self->pin->port,self->pin->number);
-    self->pin = mp_const_none;
+    self->pin = NULL;
 }
 
 uint16_t common_hal_analogio_analogin_get_value(analogio_analogin_obj_t *self) {
@@ -116,10 +116,10 @@ uint16_t common_hal_analogio_analogin_get_value(analogio_analogin_obj_t *self) {
     HAL_ADC_ConfigChannel(&AdcHandle, &sConfig);
 
     HAL_ADC_Start(&AdcHandle);
-    HAL_ADC_PollForConversion(&AdcHandle,1); 
+    HAL_ADC_PollForConversion(&AdcHandle,1);
     uint16_t value = (uint16_t)HAL_ADC_GetValue(&AdcHandle);
     HAL_ADC_Stop(&AdcHandle);
-    
+
     // // Shift the value to be 16 bit.
     return value << 4;
 }
diff --git a/ports/stm32f4/common-hal/analogio/AnalogOut.c b/ports/stm32f4/common-hal/analogio/AnalogOut.c
index 79ced0492..2ea969f50 100644
--- a/ports/stm32f4/common-hal/analogio/AnalogOut.c
+++ b/ports/stm32f4/common-hal/analogio/AnalogOut.c
@@ -39,7 +39,7 @@
 
 #include "stm32f4xx_hal.h"
 
-//DAC is shared between both channels. 
+//DAC is shared between both channels.
 #if HAS_DAC
 DAC_HandleTypeDef handle;
 #endif
@@ -97,7 +97,7 @@ bool common_hal_analogio_analogout_deinited(analogio_analogout_obj_t *self) {
 void common_hal_analogio_analogout_deinit(analogio_analogout_obj_t *self) {
     #if HAS_DAC
     reset_pin_number(self->pin->port,self->pin->number);
-    self->pin = mp_const_none;
+    self->pin = NULL;
     dac_on[self->dac_index] = false;
 
     //turn off the DAC if both channels are off
diff --git a/ports/stm32f4/common-hal/busio/I2C.c b/ports/stm32f4/common-hal/busio/I2C.c
index 1437e5e78..8e98b966d 100644
--- a/ports/stm32f4/common-hal/busio/I2C.c
+++ b/ports/stm32f4/common-hal/busio/I2C.c
@@ -100,14 +100,14 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
     GPIO_InitStruct.Mode = GPIO_MODE_AF_OD;
     GPIO_InitStruct.Pull = GPIO_PULLUP;
     GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
-    GPIO_InitStruct.Alternate = self->sda->altfn_index; 
+    GPIO_InitStruct.Alternate = self->sda->altfn_index;
     HAL_GPIO_Init(pin_port(sda->port), &GPIO_InitStruct);
 
     GPIO_InitStruct.Pin = pin_mask(scl->number);
     GPIO_InitStruct.Mode = GPIO_MODE_AF_OD;
     GPIO_InitStruct.Pull = GPIO_PULLUP;
     GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
-    GPIO_InitStruct.Alternate = self->scl->altfn_index; 
+    GPIO_InitStruct.Alternate = self->scl->altfn_index;
     HAL_GPIO_Init(pin_port(scl->port), &GPIO_InitStruct);
 
     //Note: due to I2C soft reboot issue, do not relocate clock init.
@@ -144,7 +144,7 @@ void common_hal_busio_i2c_never_reset(busio_i2c_obj_t *self) {
 }
 
 bool common_hal_busio_i2c_deinited(busio_i2c_obj_t *self) {
-    return self->sda->pin == mp_const_none;
+    return self->sda == NULL;
 }
 
 void common_hal_busio_i2c_deinit(busio_i2c_obj_t *self) {
@@ -158,8 +158,8 @@ void common_hal_busio_i2c_deinit(busio_i2c_obj_t *self) {
 
     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;
-    self->scl = mp_const_none;
+    self->sda = NULL;
+    self->scl = NULL;
 }
 
 bool common_hal_busio_i2c_probe(busio_i2c_obj_t *self, uint8_t addr) {
@@ -169,7 +169,7 @@ bool common_hal_busio_i2c_probe(busio_i2c_obj_t *self, uint8_t addr) {
 bool common_hal_busio_i2c_try_lock(busio_i2c_obj_t *self) {
     bool grabbed_lock = false;
 
-    //Critical section code that may be required at some point. 
+    //Critical section code that may be required at some point.
     // uint32_t store_primask = __get_PRIMASK();
     // __disable_irq();
     // __DMB();
@@ -195,19 +195,19 @@ 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), 
+    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) 
+    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. 
+    //Note: hard reset required due to soft reboot issue.
     #ifdef I2C1
     if (mask & (1 << 0)) {
         __HAL_RCC_I2C1_CLK_ENABLE();
diff --git a/ports/stm32f4/common-hal/busio/SPI.c b/ports/stm32f4/common-hal/busio/SPI.c
index e00b5e9f0..7e25e0a57 100644
--- a/ports/stm32f4/common-hal/busio/SPI.c
+++ b/ports/stm32f4/common-hal/busio/SPI.c
@@ -49,7 +49,7 @@ STATIC void spi_clock_enable(uint8_t mask);
 STATIC void spi_clock_disable(uint8_t mask);
 
 STATIC uint32_t get_busclock(SPI_TypeDef * instance) {
-    //SPI2 and 3 are on PCLK1, if they exist. 
+    //SPI2 and 3 are on PCLK1, if they exist.
     #ifdef SPI2
         if (instance == SPI2) return HAL_RCC_GetPCLK1Freq();
     #endif
@@ -113,7 +113,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
     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)) {
+            if ((mosi != NULL) && (miso != NULL)) {
                 //MOSI
                 for (uint j = 0; j < mosi_len; j++) {
                     if (mcu_spi_mosi_list[j].pin == mosi) {
@@ -133,11 +133,11 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
                                 self->miso = &mcu_spi_miso_list[k];
                                 break;
                             }
-                        }   
+                        }
                     }
                 }
             // if just MISO, reduce search
-            } else if (miso != mp_const_none) {
+            } else if (miso != NULL) {
                 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)) {
@@ -152,9 +152,9 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
                         self->miso = &mcu_spi_miso_list[j];
                         break;
                     }
-                }  
+                }
             // if just MOSI, reduce search
-            } else if (mosi != mp_const_none) {
+            } else if (mosi != NULL) {
                 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)) {
@@ -169,7 +169,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
                         self->miso = NULL;
                         break;
                     }
-                }  
+                }
             } else {
                 //throw an error immediately
                 mp_raise_ValueError(translate("Must provide MISO or MOSI pin"));
@@ -179,8 +179,8 @@ 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)) {
+        (self->sck != NULL && self->mosi != NULL && miso == NULL) ||
+        (self->sck != NULL && self->miso != NULL && mosi == NULL)) {
         SPIx = mcu_spi_banks[self->sck->spi_index - 1];
     } else {
         if (spi_taken) {
@@ -196,7 +196,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
     GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
     GPIO_InitStruct.Pull = GPIO_NOPULL;
     GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
-    GPIO_InitStruct.Alternate = self->sck->altfn_index; 
+    GPIO_InitStruct.Alternate = self->sck->altfn_index;
     HAL_GPIO_Init(pin_port(sck->port), &GPIO_InitStruct);
 
     if (self->mosi != NULL) {
@@ -204,7 +204,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
         GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
         GPIO_InitStruct.Pull = GPIO_NOPULL;
         GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
-        GPIO_InitStruct.Alternate = self->mosi->altfn_index; 
+        GPIO_InitStruct.Alternate = self->mosi->altfn_index;
         HAL_GPIO_Init(pin_port(mosi->port), &GPIO_InitStruct);
     }
 
@@ -213,14 +213,14 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
         GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
         GPIO_InitStruct.Pull = GPIO_NOPULL;
         GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
-        GPIO_InitStruct.Alternate = self->miso->altfn_index; 
+        GPIO_InitStruct.Alternate = self->miso->altfn_index;
         HAL_GPIO_Init(pin_port(miso->port), &GPIO_InitStruct);
     }
 
     spi_clock_enable(1 << (self->sck->spi_index - 1));
     reserved_spi[self->sck->spi_index - 1] = true;
-    
-    self->handle.Instance = SPIx; 
+
+    self->handle.Instance = SPIx;
     self->handle.Init.Mode = SPI_MODE_MASTER;
     // Direction change only required for RX-only, see RefMan RM0090:884
     self->handle.Init.Direction = (self->mosi == NULL) ? SPI_CR1_RXONLY : SPI_DIRECTION_2LINES;
@@ -269,7 +269,7 @@ void common_hal_busio_spi_never_reset(busio_spi_obj_t *self) {
 }
 
 bool common_hal_busio_spi_deinited(busio_spi_obj_t *self) {
-    return self->sck->pin == mp_const_none;
+    return self->sck->pin == NULL;
 }
 
 void common_hal_busio_spi_deinit(busio_spi_obj_t *self) {
@@ -287,15 +287,15 @@ void common_hal_busio_spi_deinit(busio_spi_obj_t *self) {
     if (self->miso != NULL) {
         reset_pin_number(self->miso->pin->port,self->miso->pin->number);
     }
-    self->sck = mp_const_none;
-    self->mosi = mp_const_none;
-    self->miso = mp_const_none;
+    self->sck = NULL;
+    self->mosi = NULL;
+    self->miso = NULL;
 }
 
 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
-    if (baudrate == self->baudrate && polarity== self->polarity 
+    if (baudrate == self->baudrate && polarity== self->polarity
         && phase == self->phase && bits == self->bits) {
         return true;
     }
@@ -307,7 +307,7 @@ bool common_hal_busio_spi_configure(busio_spi_obj_t *self,
     self->handle.Init.CLKPolarity = (polarity) ? SPI_POLARITY_HIGH : SPI_POLARITY_LOW;
     self->handle.Init.CLKPhase = (phase) ? SPI_PHASE_2EDGE : SPI_PHASE_1EDGE;
 
-    self->handle.Init.BaudRatePrescaler = stm32_baud_to_spi_div(baudrate, &self->prescaler, 
+    self->handle.Init.BaudRatePrescaler = stm32_baud_to_spi_div(baudrate, &self->prescaler,
                                             get_busclock(self->handle.Instance));
 
     if (HAL_SPI_Init(&self->handle) != HAL_OK)
@@ -325,7 +325,7 @@ bool common_hal_busio_spi_configure(busio_spi_obj_t *self,
 bool common_hal_busio_spi_try_lock(busio_spi_obj_t *self) {
     bool grabbed_lock = false;
 
-    //Critical section code that may be required at some point. 
+    //Critical section code that may be required at some point.
     // uint32_t store_primask = __get_PRIMASK();
     // __disable_irq();
     // __DMB();
@@ -367,7 +367,7 @@ bool common_hal_busio_spi_read(busio_spi_obj_t *self,
     return result == HAL_OK;
 }
 
-bool common_hal_busio_spi_transfer(busio_spi_obj_t *self, 
+bool common_hal_busio_spi_transfer(busio_spi_obj_t *self,
         uint8_t *data_out, uint8_t *data_in, size_t len) {
     if (self->miso == NULL || self->mosi == NULL) {
         mp_raise_ValueError(translate("Missing MISO or MOSI Pin"));
diff --git a/ports/stm32f4/common-hal/busio/UART.c b/ports/stm32f4/common-hal/busio/UART.c
index 3c1909259..0b434fd02 100644
--- a/ports/stm32f4/common-hal/busio/UART.c
+++ b/ports/stm32f4/common-hal/busio/UART.c
@@ -86,12 +86,12 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     bool uart_taken = false;
     uint8_t uart_index = 0; //origin 0 corrected
 
-    if ((rts != mp_const_none) || (cts != mp_const_none) || (rs485_dir != mp_const_none) || (rs485_invert == true)) {
+    if ((rts != NULL) || (cts != NULL) || (rs485_dir != NULL) || (rs485_invert == true)) {
         mp_raise_ValueError(translate("RTS/CTS/RS485 Not yet supported on this device"));
     }
-    
+
     //Can have both pins, or either
-    if ((tx != mp_const_none) && (rx != mp_const_none)) {
+    if ((tx != NULL) && (rx != NULL)) {
         //normal find loop if both pins exist
         for (uint i = 0; i < tx_len; i++) {
             if (mcu_uart_tx_list[i].pin == tx) {
@@ -115,7 +115,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
         uart_index = self->tx->uart_index - 1;
         USARTx = assign_uart_or_throw(self, (self->tx != NULL && self->rx != NULL),
             uart_index, uart_taken);
-    } else if (tx == mp_const_none) {
+    } else if (tx == NULL) {
         //If there is no tx, run only rx
         for (uint i = 0; i < rx_len; i++) {
             if (mcu_uart_rx_list[i].pin == rx) {
@@ -132,7 +132,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
         uart_index = self->rx->uart_index - 1;
         USARTx = assign_uart_or_throw(self, (self->rx != NULL),
             uart_index, uart_taken);
-    } else if (rx == mp_const_none) {
+    } else if (rx == NULL) {
         //If there is no rx, run only tx
         for (uint i = 0; i < tx_len; i++) {
             if (mcu_uart_tx_list[i].pin == tx) {
@@ -236,7 +236,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
 }
 
 bool common_hal_busio_uart_deinited(busio_uart_obj_t *self) {
-    return self->tx->pin == mp_const_none;
+    return self->tx->pin == NULL;
 }
 
 void common_hal_busio_uart_deinit(busio_uart_obj_t *self) {
@@ -244,8 +244,8 @@ void common_hal_busio_uart_deinit(busio_uart_obj_t *self) {
 
     reset_pin_number(self->tx->pin->port,self->tx->pin->number);
     reset_pin_number(self->rx->pin->port,self->rx->pin->number);
-    self->tx = mp_const_none;
-    self->rx = mp_const_none;
+    self->tx = NULL;
+    self->rx = NULL;
     gc_free(self->rbuf.buf);
     self->rbuf.size = 0;
     self->rbuf.iput = self->rbuf.iget = 0;
diff --git a/ports/stm32f4/common-hal/digitalio/DigitalInOut.c b/ports/stm32f4/common-hal/digitalio/DigitalInOut.c
index 36c1075e2..be2db4dac 100644
--- a/ports/stm32f4/common-hal/digitalio/DigitalInOut.c
+++ b/ports/stm32f4/common-hal/digitalio/DigitalInOut.c
@@ -54,7 +54,7 @@ digitalinout_result_t common_hal_digitalio_digitalinout_construct(
 }
 
 bool common_hal_digitalio_digitalinout_deinited(digitalio_digitalinout_obj_t *self) {
-    return self->pin == mp_const_none;
+    return self->pin == NULL;
 }
 
 void common_hal_digitalio_digitalinout_deinit(digitalio_digitalinout_obj_t *self) {
@@ -63,7 +63,7 @@ void common_hal_digitalio_digitalinout_deinit(digitalio_digitalinout_obj_t *self
     }
 
     reset_pin_number(self->pin->port, self->pin->number);
-    self->pin = mp_const_none;
+    self->pin = NULL;
 }
 
 void common_hal_digitalio_digitalinout_switch_to_input(
@@ -90,7 +90,7 @@ void common_hal_digitalio_digitalinout_switch_to_output(
 digitalio_direction_t common_hal_digitalio_digitalinout_get_direction(
         digitalio_digitalinout_obj_t *self) {
 
-    return (LL_GPIO_GetPinMode(pin_port(self->pin->port), pin_mask(self->pin->number)) 
+    return (LL_GPIO_GetPinMode(pin_port(self->pin->port), pin_mask(self->pin->number))
         == LL_GPIO_MODE_INPUT) ? DIRECTION_INPUT : DIRECTION_OUTPUT;
 }
 
@@ -111,7 +111,7 @@ void common_hal_digitalio_digitalinout_set_drive_mode(
         digitalio_drive_mode_t drive_mode) {
     GPIO_InitTypeDef GPIO_InitStruct = {0};
     GPIO_InitStruct.Pin = pin_mask(self->pin->number);
-    GPIO_InitStruct.Mode = (drive_mode == DRIVE_MODE_OPEN_DRAIN ? 
+    GPIO_InitStruct.Mode = (drive_mode == DRIVE_MODE_OPEN_DRAIN ?
         GPIO_MODE_OUTPUT_OD : GPIO_MODE_OUTPUT_PP);
     GPIO_InitStruct.Pull = GPIO_NOPULL;
     GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
@@ -121,7 +121,7 @@ void common_hal_digitalio_digitalinout_set_drive_mode(
 digitalio_drive_mode_t common_hal_digitalio_digitalinout_get_drive_mode(
         digitalio_digitalinout_obj_t *self) {
 
-    return LL_GPIO_GetPinOutputType(pin_port(self->pin->port), pin_mask(self->pin->number)) 
+    return LL_GPIO_GetPinOutputType(pin_port(self->pin->port), pin_mask(self->pin->number))
         == LL_GPIO_OUTPUT_OPENDRAIN ? DRIVE_MODE_OPEN_DRAIN : DRIVE_MODE_PUSH_PULL;
 }
 
@@ -145,7 +145,7 @@ void common_hal_digitalio_digitalinout_set_pull(
 
 digitalio_pull_t common_hal_digitalio_digitalinout_get_pull(
         digitalio_digitalinout_obj_t *self) {
-    
+
 
     switch (LL_GPIO_GetPinPull(pin_port(self->pin->port), pin_mask(self->pin->number))) {
         case LL_GPIO_PULL_UP:
diff --git a/ports/stm32f4/common-hal/pulseio/PWMOut.c b/ports/stm32f4/common-hal/pulseio/PWMOut.c
index 4bb3afae4..d62ee2a38 100644
--- a/ports/stm32f4/common-hal/pulseio/PWMOut.c
+++ b/ports/stm32f4/common-hal/pulseio/PWMOut.c
@@ -72,7 +72,7 @@ STATIC uint32_t timer_get_internal_duty(uint16_t duty, uint32_t period) {
     return (duty*period) / ((1 << 16) - 1);
 }
 
-STATIC void timer_get_optimal_divisors(uint32_t*period, uint32_t*prescaler, 
+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++) {
@@ -139,7 +139,7 @@ pwmout_result_t common_hal_pulseio_pwmout_construct(pulseio_pwmout_obj_t* self,
                 first_time_setup = false; //skip setting up the timer
             }
             //No problems taken, so set it up
-            self->tim = l_tim; 
+            self->tim = l_tim;
             break;
         }
     }
@@ -182,7 +182,7 @@ pwmout_result_t common_hal_pulseio_pwmout_construct(pulseio_pwmout_obj_t* self,
 
     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_optimal_divisors(&period, &prescaler, frequency,
                             timer_get_source_freq(self->tim->tim_index));
 
     //Timer init
@@ -240,7 +240,7 @@ void common_hal_pulseio_pwmout_reset_ok(pulseio_pwmout_obj_t *self) {
 }
 
 bool common_hal_pulseio_pwmout_deinited(pulseio_pwmout_obj_t* self) {
-    return self->tim == mp_const_none;
+    return self->tim == NULL;
 }
 
 void common_hal_pulseio_pwmout_deinit(pulseio_pwmout_obj_t* self) {
@@ -255,7 +255,7 @@ void common_hal_pulseio_pwmout_deinit(pulseio_pwmout_obj_t* self) {
         HAL_TIM_PWM_Stop(&self->handle, self->channel);
     }
     reset_pin_number(self->tim->pin->port,self->tim->pin->number);
-    self->tim = mp_const_none;
+    self->tim = NULL;
 
     //if reserved timer has no active channels, we can disable it
     if (!reserved_tim[self->tim->tim_index - 1]) {
@@ -276,13 +276,13 @@ 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) { 
+    if (frequency == self->frequency) {
         return;
     }
 
     uint32_t prescaler = 0;
     uint32_t period = 0;
-    timer_get_optimal_divisors(&period, &prescaler, frequency, 
+    timer_get_optimal_divisors(&period, &prescaler, frequency,
                                 timer_get_source_freq(self->tim->tim_index));
 
     //shut down
@@ -290,7 +290,7 @@ void common_hal_pulseio_pwmout_set_frequency(pulseio_pwmout_obj_t* self, uint32_
 
     //Only change altered values
     self->handle.Init.Period = period - 1;
-    self->handle.Init.Prescaler = prescaler - 1; 
+    self->handle.Init.Prescaler = prescaler - 1;
 
     //restart everything, adjusting for new speed
     if (HAL_TIM_PWM_Init(&self->handle) != HAL_OK) {
diff --git a/ports/stm32f4/mpconfigport.mk b/ports/stm32f4/mpconfigport.mk
index f214282cb..493f32c63 100644
--- a/ports/stm32f4/mpconfigport.mk
+++ b/ports/stm32f4/mpconfigport.mk
@@ -71,5 +71,7 @@ endif
 
 CFLAGS += -DMICROPY_CPYTHON_COMPAT=1
 
+MICROPY_PY_ULAB = 1
+
 #ifeq ($(MCU_SUB_VARIANT), stm32f412zx)
 #endif