diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 6b694c6..2a36a0c 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -119,6 +119,8 @@ jobs:
         - 'imxrt1020_evk'
         - 'imxrt1060_evk'
         - 'metro_m7_1011'
+        #stm32f3
+        - 'stm32f303disco'
         # stm32f4
         - 'feather_stm32f405_express'
         - 'stm32f411ve_discovery'
diff --git a/.gitmodules b/.gitmodules
index 1408d1d..3907601 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -25,3 +25,9 @@
 [submodule "lib/sct_neopixel"]
 	path = lib/sct_neopixel
 	url = https://github.com/gsteiert/sct_neopixel
+	[submodule "lib/st/stm32f3xx_hal_driver"]
+		path = lib/st/stm32f3xx_hal_driver
+		url = https://github.com/STMicroelectronics/stm32f3xx_hal_driver
+	[submodule "lib/st/cmsis_device_f3"]
+		path = lib/st/cmsis_device_f3
+		url = https://github.com/STMicroelectronics/cmsis_device_f3.git
diff --git a/lib/st/cmsis_device_f3 b/lib/st/cmsis_device_f3
new file mode 160000
index 0000000..6cb335b
--- /dev/null
+++ b/lib/st/cmsis_device_f3
@@ -0,0 +1 @@
+Subproject commit 6cb335bfffcc63caa4e8104cc11ba239556b6f42
diff --git a/lib/st/stm32f3xx_hal_driver b/lib/st/stm32f3xx_hal_driver
new file mode 160000
index 0000000..a0007fb
--- /dev/null
+++ b/lib/st/stm32f3xx_hal_driver
@@ -0,0 +1 @@
+Subproject commit a0007fb36cb5eaf2f875aaa133fd06de818c38ae
diff --git a/ports/make.mk b/ports/make.mk
index 9030922..6f6d863 100644
--- a/ports/make.mk
+++ b/ports/make.mk
@@ -27,7 +27,7 @@ check_defined = \
 __check_defined = \
     $(if $(value $1),, \
     $(error Undefined make flag: $1$(if $2, ($2))))
-    
+
 #-------------- Select the board to build for. ------------
 BOARD_LIST = $(sort $(subst /.,,$(subst boards/,,$(wildcard boards/*/.))))
 
diff --git a/ports/stm32f3/Makefile b/ports/stm32f3/Makefile
new file mode 100644
index 0000000..369d0c7
--- /dev/null
+++ b/ports/stm32f3/Makefile
@@ -0,0 +1,79 @@
+UF2_FAMILY_ID = 0x6b846188
+CROSS_COMPILE = arm-none-eabi-
+
+ST_HAL_DRIVER = lib/st/stm32f3xx_hal_driver
+ST_CMSIS = lib/st/cmsis_device_f3
+CMSIS_5 = lib/CMSIS_5
+
+# List of git submodules that is included as part of the UF2 version
+GIT_SUBMODULES = CMSIS_5 st/cmsis_device_f3 st/stm32f3xx_hal_driver tinyusb
+
+include ../make.mk
+
+# Port Compiler Flags
+CFLAGS += \
+  -flto \
+  -mthumb \
+  -mabi=aapcs \
+  -mcpu=cortex-m4 \
+  -mfloat-abi=hard \
+  -mfpu=fpv4-sp-d16 \
+  -nostdlib -nostartfiles \
+  -DCFG_TUSB_MCU=OPT_MCU_STM32F3
+
+# suppress warning caused by vendor mcu driver
+CFLAGS += -Wno-error=cast-align -Wno-error=unused-parameter
+
+LD_FILES ?= $(PORT_DIR)/linker/STM32F303VCTx_FLASH.ld
+
+# Port source
+PORT_SRC_C += \
+	$(addprefix $(CURRENT_PATH)/, $(wildcard *.c)) \
+	$(ST_CMSIS)/Source/Templates/system_stm32f3xx.c \
+	$(ST_HAL_DRIVER)/Src/stm32f3xx_hal.c \
+	$(ST_HAL_DRIVER)/Src/stm32f3xx_hal_cortex.c \
+	$(ST_HAL_DRIVER)/Src/stm32f3xx_hal_rcc.c \
+	$(ST_HAL_DRIVER)/Src/stm32f3xx_hal_rcc_ex.c \
+	$(ST_HAL_DRIVER)/Src/stm32f3xx_hal_gpio.c \
+	$(ST_HAL_DRIVER)/Src/stm32f3xx_hal_flash.c \
+	$(ST_HAL_DRIVER)/Src/stm32f3xx_hal_flash_ex.c \
+	$(ST_HAL_DRIVER)/Src/stm32f3xx_hal_uart.c
+
+SRC_C += \
+	$(PORT_SRC_C) \
+	lib/tinyusb/src/portable/st/stm32_fsdev/dcd_stm32_fsdev.c \
+
+# Port include
+INC += \
+	$(TOP)/$(CMSIS_5)/CMSIS/Core/Include \
+	$(TOP)/$(ST_CMSIS)/Include \
+	$(TOP)/$(ST_HAL_DRIVER)/Inc
+
+include ../rules.mk
+
+# flash target ROM bootloader
+flash-dfu-util: $(BUILD)/$(OUTNAME).bin
+	dfu-util -R -a 0 --dfuse-address 0x08000000 -D $<
+
+#-------------- Self-update  --------------
+SELF_CFLAGS  = $(CFLAGS) -DTINYUF2_SELF_UPDATE
+SELF_LDFLAGS = $(LDFLAGS)
+SELF_LD_FILES ?= $(LD_FILES)
+SELF_ASFLAGS = $(ASFLAGS)
+
+include ../self_update.mk
+
+# self-update uf2 file
+$(SELF_BUILD_OBJ)/$(SELF_OUTNAME).uf2: $(SELF_BUILD_OBJ)/$(SELF_OUTNAME).hex
+	@echo CREATE $@
+	$(PYTHON3) $(TOP)/lib/uf2/utils/uf2conv.py -f $(UF2_FAMILY_ID) -c -o $@ $^
+
+$(SELF_BUILD_OBJ)/$(SELF_OUTNAME).hex: $(SELF_BUILD_OBJ)/$(SELF_OUTNAME).elf
+	@echo CREATE $@
+	@$(OBJCOPY) -O ihex $^ $@
+
+# required for self-update elf compile
+$(SELF_BUILD_OBJ)/self_update/$(OUTNAME).c:
+	@echo "const unsigned long bindata_len = 1;" > $@
+	@echo "const unsigned char bindata[] __attribute__((aligned(16))) = { 0 };" >> $@
+	#$(PYTHON3) $(TOP)/lib/uf2/utils/uf2conv.py --carray $^ -o $@
diff --git a/ports/stm32f3/board_flash.c b/ports/stm32f3/board_flash.c
new file mode 100644
index 0000000..152d723
--- /dev/null
+++ b/ports/stm32f3/board_flash.c
@@ -0,0 +1,160 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Ha Thach for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "board_api.h"
+#include "tusb.h" // for logging
+
+#define FLASH_CACHE_SIZE          512
+#define FLASH_CACHE_INVALID_ADDR  0xffffffff
+
+//--------------------------------------------------------------------+
+//define flash space, reserve first 8 sectors for bootloader up to 3FFF
+//--------------------------------------------------------------------+
+
+#define BOARD_FLASH_SECTORS 64
+#define BOARD_FIRST_FLASH_SECTOR_TO_ERASE 8
+
+#define APP_LOAD_ADDRESS 0x08004000
+
+/* flash parameters */
+#define SIZE 2048
+
+static uint8_t erasedSectors[BOARD_FLASH_SECTORS];
+
+uint32_t flash_func_sector_size(unsigned sector)
+{
+  if (sector < BOARD_FLASH_SECTORS) {
+    return SIZE;
+  }
+
+  return 0;
+}
+
+static bool is_blank(uint32_t addr, uint32_t size)
+{
+  for (uint32_t i = 0; i < size; i += sizeof(uint32_t)) {
+    if (*(uint32_t*)(addr + i) != 0xffffffff) {
+      return false;
+    }
+  }
+  return true;
+}
+
+                    //ADDR            data
+void flash_write(uint32_t dst, const uint8_t *src, int len)
+{
+   // assume sector 0-7 (bootloader) is same size as sector 1
+  uint32_t addr = APP_LOAD_ADDRESS;
+  uint32_t sector = 0;
+  int erased = false;
+  uint32_t size = 0;
+
+  for ( unsigned i = 0; i < BOARD_FLASH_SECTORS; i++ )
+  {
+    size = flash_func_sector_size(i);
+    if ( addr + size > dst )
+    {
+      sector = i + 1;
+      erased = erasedSectors[i];
+      erasedSectors[i] = 1;    // don't erase anymore - we will continue writing here!
+      break;
+    }
+    addr += size;
+  }
+
+  if (sector == 0)
+  {
+    TU_LOG1("invalid sector");
+  }
+
+  HAL_FLASH_Unlock();
+
+  if (!erased && !is_blank(addr, size))
+  {
+    uint32_t SectorError = 0;
+
+    TU_LOG1("Erase: %08lX size = %lu\n", addr, size);
+
+    FLASH_EraseInitTypeDef EraseInit;
+    EraseInit.TypeErase = FLASH_TYPEERASE_PAGES;
+    EraseInit.PageAddress = addr;
+    EraseInit.NbPages = ((0x08040000 - addr)/size);
+
+    HAL_FLASHEx_Erase(&EraseInit, &SectorError);
+    FLASH_WaitForLastOperation(HAL_MAX_DELAY);
+
+    if (SectorError != 0xFFFFFFFF)
+    {
+      TU_LOG1("failed to erase!");
+    }
+  }
+
+  for (int i = 0; i < len; i += 4)
+  {
+    HAL_FLASH_Program(FLASH_TYPEPROGRAM_WORD, dst + i, (uint64_t) (*(uint32_t*)(src + i)) );
+  }
+
+  if (memcmp((void*)dst, src, len) != 0)
+  {
+    TU_LOG1("failed to write");
+  }
+}
+
+//--------------------------------------------------------------------+
+//
+//--------------------------------------------------------------------+
+void board_flash_init(void)
+{
+
+}
+
+uint32_t board_flash_size(void)
+{
+  return BOARD_FLASH_SIZE;
+}
+
+void board_flash_read(uint32_t addr, void* buffer, uint32_t len)
+{
+  memcpy(buffer, (void*) addr, len);
+}
+
+void board_flash_flush(void)
+{
+}
+
+// TODO not working quite yet
+void board_flash_write (uint32_t addr, void const *data, uint32_t len)
+{
+  // TODO skip matching contents
+  flash_write(addr, data, len);
+}
+
+
+#ifdef TINYUF2_SELF_UPDATE
+void board_self_update(const uint8_t * bootloader_bin, uint32_t bootloader_len)
+{
+  (void) bootloader_bin;
+  (void) bootloader_len;
+}
+#endif
diff --git a/ports/stm32f3/boards.c b/ports/stm32f3/boards.c
new file mode 100644
index 0000000..013fd18
--- /dev/null
+++ b/ports/stm32f3/boards.c
@@ -0,0 +1,327 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Ha Thach for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "board_api.h"
+#include "stm32f3xx_hal.h"
+#include "tusb.h"
+
+//--------------------------------------------------------------------+
+// MACRO TYPEDEF CONSTANT ENUM DECLARATION
+//--------------------------------------------------------------------+
+
+#define STM32_UUID ((uint32_t *)0x1FFFF7AC)
+
+static UART_HandleTypeDef UartHandle;
+
+void board_init(void)
+{
+  clock_init();
+  SystemCoreClockUpdate();
+
+  // disable systick
+  board_timer_stop();
+
+  __HAL_RCC_GPIOA_CLK_ENABLE();
+  __HAL_RCC_GPIOB_CLK_ENABLE();
+  __HAL_RCC_GPIOC_CLK_ENABLE();
+  __HAL_RCC_GPIOD_CLK_ENABLE();
+  __HAL_RCC_GPIOE_CLK_ENABLE();
+
+  GPIO_InitTypeDef  GPIO_InitStruct;
+
+  #ifdef BUTTON_PIN
+  GPIO_InitStruct.Pin = BUTTON_PIN;
+  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
+  GPIO_InitStruct.Pull = GPIO_PULLDOWN;
+  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
+  HAL_GPIO_Init(BUTTON_PORT, &GPIO_InitStruct);
+  #endif
+
+  #ifdef LED_PIN
+  GPIO_InitStruct.Pin = LED_PIN;
+  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
+  GPIO_InitStruct.Pull = GPIO_PULLUP;
+  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
+  HAL_GPIO_Init(LED_PORT, &GPIO_InitStruct);
+
+  board_led_write(0);
+  #endif
+
+  #if NEOPIXEL_NUMBER
+  GPIO_InitStruct.Pin = NEOPIXEL_PIN;
+  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
+  GPIO_InitStruct.Pull = GPIO_PULLUP;
+  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
+  HAL_GPIO_Init(NEOPIXEL_PORT, &GPIO_InitStruct);
+  #endif
+
+  #if defined(UART_DEV) && CFG_TUSB_DEBUG
+  UART_CLOCK_ENABLE();
+
+  GPIO_InitStruct.Pin       = UART_TX_PIN | UART_RX_PIN;
+  GPIO_InitStruct.Mode      = GPIO_MODE_AF_PP;
+  GPIO_InitStruct.Pull      = GPIO_PULLUP;
+  GPIO_InitStruct.Speed     = GPIO_SPEED_FREQ_HIGH;
+  GPIO_InitStruct.Alternate = GPIO_AF7_USART2;
+  HAL_GPIO_Init(UART_GPIO_PORT, &GPIO_InitStruct);
+
+  UartHandle.Instance        = UART_DEV;
+  UartHandle.Init.BaudRate   = 115200;
+  UartHandle.Init.WordLength = UART_WORDLENGTH_8B;
+  UartHandle.Init.StopBits   = UART_STOPBITS_1;
+  UartHandle.Init.Parity     = UART_PARITY_NONE;
+  UartHandle.Init.HwFlowCtl  = UART_HWCONTROL_NONE;
+  UartHandle.Init.Mode       = UART_MODE_TX_RX;
+  HAL_UART_Init(&UartHandle);
+  #endif
+}
+
+void board_dfu_init(void)
+{
+  __HAL_RCC_SYSCFG_CLK_ENABLE();
+  __HAL_REMAPINTERRUPT_USB_ENABLE();
+
+  GPIO_InitTypeDef  GPIO_InitStruct;
+  GPIO_InitStruct.Pin = (GPIO_PIN_11 | GPIO_PIN_12);
+  GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
+  GPIO_InitStruct.Pull = GPIO_NOPULL;
+  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
+  GPIO_InitStruct.Alternate = GPIO_AF14_USB;
+  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
+
+  // Enable USB clock
+  __HAL_RCC_USB_CLK_ENABLE();
+}
+
+void board_dfu_complete(void)
+{
+  NVIC_SystemReset();
+}
+
+bool board_app_valid(void)
+{
+  if((((*(uint32_t*)BOARD_FLASH_APP_START) - BOARD_RAM_START) <= BOARD_RAM_SIZE)) // && ((*(uint32_t*)BOARD_FLASH_APP_START + 4) > BOARD_FLASH_APP_START) && ((*(uint32_t*)BOARD_FLASH_APP_START + 4) < BOARD_FLASH_APP_START + BOARD_FLASH_SIZE)
+  {
+    return true;
+  } else
+  {
+    return false;
+  }
+}
+
+void board_app_jump(void)
+{
+  GPIO_InitTypeDef  GPIO_InitStruct;
+  GPIO_InitStruct.Pin = GPIO_PIN_12;
+  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
+  GPIO_InitStruct.Pull = GPIO_NOPULL;
+  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
+  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
+  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_12, GPIO_PIN_RESET);
+
+  #ifdef BUTTON_PIN
+  HAL_GPIO_DeInit(BUTTON_PORT, BUTTON_PIN);
+  #endif
+
+  #ifdef LED_PIN
+  HAL_GPIO_DeInit(LED_PORT, LED_PIN);
+  #endif
+
+  #if NEOPIXEL_NUMBER
+  HAL_GPIO_DeInit(NEOPIXEL_PORT, NEOPIXEL_PIN);
+  #endif
+
+  #if defined(UART_DEV) && CFG_TUSB_DEBUG
+  HAL_UART_DeInit(&UartHandle);
+  HAL_GPIO_DeInit(UART_GPIO_PORT, UART_TX_PIN | UART_RX_PIN);
+  #endif
+
+  HAL_GPIO_DeInit(GPIOA, GPIO_PIN_12 | GPIO_PIN_11);
+
+  __HAL_RCC_GPIOA_CLK_DISABLE();
+  __HAL_RCC_GPIOB_CLK_DISABLE();
+  __HAL_RCC_GPIOC_CLK_DISABLE();
+  __HAL_RCC_GPIOD_CLK_DISABLE();
+  __HAL_RCC_GPIOE_CLK_DISABLE();
+
+  HAL_RCC_DeInit();
+  HAL_DeInit();
+
+  // TODO protect bootloader region
+
+  volatile uint32_t const * app_vector = (volatile uint32_t const*) BOARD_FLASH_APP_START;
+
+  /* switch exception handlers to the application */
+  SCB->VTOR = (uint32_t) BOARD_FLASH_APP_START;
+
+  // Set stack pointer
+  __set_MSP(app_vector[0]);
+
+  // Jump to Application Entry
+  asm("bx %0" ::"r"(app_vector[1]));
+}
+
+uint8_t board_usb_get_serial(uint8_t serial_id[16])
+{
+  uint8_t const len = 12;
+  memcpy(serial_id, STM32_UUID, len);
+  return len;
+}
+
+//--------------------------------------------------------------------+
+// LED pattern
+//--------------------------------------------------------------------+
+
+void board_led_write(uint32_t state)
+{
+  HAL_GPIO_WritePin(LED_PORT, LED_PIN, state ? LED_STATE_ON : (1-LED_STATE_ON));
+}
+
+#if NEOPIXEL_NUMBER
+#define MAGIC_800_INT   900000  // ~1.11 us -> 1.2  field
+#define MAGIC_800_T0H  2800000  // ~0.36 us -> 0.44 field
+#define MAGIC_800_T1H  1350000  // ~0.74 us -> 0.84 field
+
+static inline uint8_t apply_percentage(uint8_t brightness)
+{
+  return (uint8_t) ((brightness*NEOPIXEL_BRIGHTNESS) >> 8);
+}
+
+void board_rgb_write(uint8_t const rgb[])
+{
+  // neopixel color order is GRB
+  uint8_t const pixels[3] = { apply_percentage(rgb[1]), apply_percentage(rgb[0]), apply_percentage(rgb[2]) };
+  uint32_t const numBytes = 3;
+
+  uint8_t const *p = pixels, *end = p + numBytes;
+  uint8_t pix = *p++, mask = 0x80;
+  uint32_t start = 0;
+  uint32_t cyc = 0;
+
+  //assumes 800_000Hz frequency
+  //Theoretical values here are 800_000 -> 1.25us, 2500000->0.4us, 1250000->0.8us
+  //TODO: try to get dynamic weighting working again
+  uint32_t const sys_freq = HAL_RCC_GetSysClockFreq();
+  uint32_t const interval = sys_freq/MAGIC_800_INT;
+  uint32_t const t0       = sys_freq/MAGIC_800_T0H;
+  uint32_t const t1       = sys_freq/MAGIC_800_T1H;
+
+  __disable_irq();
+
+  // Enable DWT in debug core. Useable when interrupts disabled, as opposed to Systick->VAL
+  CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
+  DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
+  DWT->CYCCNT = 0;
+
+  for(;;) {
+    cyc = (pix & mask) ? t1 : t0;
+    start = DWT->CYCCNT;
+
+    HAL_GPIO_WritePin(NEOPIXEL_PORT, NEOPIXEL_PIN, 1);
+    while((DWT->CYCCNT - start) < cyc);
+
+    HAL_GPIO_WritePin(NEOPIXEL_PORT, NEOPIXEL_PIN, 0);
+    while((DWT->CYCCNT - start) < interval);
+
+    if(!(mask >>= 1)) {
+      if(p >= end) break;
+      pix  = *p++;
+      mask = 0x80;
+    }
+  }
+
+  __enable_irq();
+}
+
+#else
+
+void board_rgb_write(uint8_t const rgb[])
+{
+  (void) rgb;
+}
+
+#endif
+
+//--------------------------------------------------------------------+
+// Timer
+//--------------------------------------------------------------------+
+
+void board_timer_start(uint32_t ms)
+{
+  SysTick_Config( (SystemCoreClock/1000) * ms );
+}
+
+void board_timer_stop(void)
+{
+  SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;
+}
+
+void SysTick_Handler (void)
+{
+  board_timer_handler();
+}
+
+int board_uart_write(void const * buf, int len)
+{
+#if defined(UART_DEV) && CFG_TUSB_DEBUG
+  HAL_UART_Transmit(&UartHandle, (uint8_t*) buf, len, 0xffff);
+  return len;
+#else
+  (void) buf; (void) len;
+  (void) UartHandle;
+  return 0;
+#endif
+}
+
+#ifndef TINYUF2_SELF_UPDATE
+
+// Forward USB interrupt events to TinyUSB IRQ Handler
+void USB_HP_IRQHandler(void)
+{
+  tud_int_handler(0);
+}
+
+// USB low-priority interrupt (Channel 75): Triggered by all USB events
+// (Correct transfer, USB reset, etc.). The firmware has to check the
+// interrupt source before serving the interrupt.
+void USB_LP_IRQHandler(void)
+{
+  tud_int_handler(0);
+}
+
+// USB wakeup interrupt (Channel 76): Triggered by the wakeup event from the USB
+// Suspend mode.
+void USBWakeUp_RMP_IRQHandler(void)
+{
+  tud_int_handler(0);
+}
+
+#endif
+
+// Required by __libc_init_array in startup code if we are compiling using
+// -nostdlib/-nostartfiles.
+void _init(void)
+{
+
+}
diff --git a/ports/stm32f3/boards.h b/ports/stm32f3/boards.h
new file mode 100644
index 0000000..25880e1
--- /dev/null
+++ b/ports/stm32f3/boards.h
@@ -0,0 +1,60 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020 Ha Thach (tinyusb.org) for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef BOARDS_H_
+#define BOARDS_H_
+
+#ifdef __cplusplus
+ extern "C" {
+#endif
+
+#include "stm32f3xx.h"
+#include "stm32f3xx_hal_conf.h"
+
+#include "board.h"
+
+// Flash Start Address of Application
+#define BOARD_FLASH_APP_START   0x08004000
+#define BOARD_RAM_START 0x20000000
+#define BOARD_RAM_SIZE 0x9FFF
+
+// Double Reset tap to enter DFU
+#define TINYUF2_DFU_DOUBLE_TAP      1
+
+//#define USE_RGB                 NEOPIXEL_NUMBER
+
+// Brightness percentage from 1 to 255
+#ifndef NEOPIXEL_BRIGHTNESS
+#define NEOPIXEL_BRIGHTNESS   0x10
+#endif
+
+#ifdef LED_PIN
+#define TINYUF2_LED 1
+#endif
+
+#ifdef __cplusplus
+ }
+#endif
+
+#endif /* BOARDS_H_ */
diff --git a/ports/stm32f3/boards/stm32f303disco/board.h b/ports/stm32f3/boards/stm32f303disco/board.h
new file mode 100644
index 0000000..9c9e187
--- /dev/null
+++ b/ports/stm32f3/boards/stm32f303disco/board.h
@@ -0,0 +1,123 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Ha Thach for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef BOARD_H_
+#define BOARD_H_
+
+//--------------------------------------------------------------------+
+// LED
+//--------------------------------------------------------------------+
+
+#define LED_PORT              GPIOE
+#define LED_PIN               GPIO_PIN_10
+#define LED_STATE_ON          1
+
+//#define BUTTON_PORT           GPIOA
+//#define BUTTON_PIN            GPIO_PIN_0
+//#define BUTTON_STATE_ACTIVE   1
+
+
+//--------------------------------------------------------------------+
+// Neopixel
+//--------------------------------------------------------------------+
+
+//// Number of neopixels
+#define NEOPIXEL_NUMBER       0
+
+//#define NEOPIXEL_PORT         GPIOC
+//#define NEOPIXEL_PIN          GPIO_PIN_0
+//
+//// Brightness percentage from 1 to 255
+//#define NEOPIXEL_BRIGHTNESS   0x10
+
+
+//--------------------------------------------------------------------+
+// Flash
+//--------------------------------------------------------------------+
+
+// Flash size of the board
+#define BOARD_FLASH_SIZE  (256 * 1024)
+
+//--------------------------------------------------------------------+
+// USB UF2
+//--------------------------------------------------------------------+
+
+// TODO VID/PID aren't assigned for this board
+#define USB_VID           0xcafe
+#define USB_PID           0xffff
+#define USB_MANUFACTURER  "ST"
+#define USB_PRODUCT       "STM32F303 Discovery"
+
+#define UF2_PRODUCT_NAME  USB_MANUFACTURER " " USB_PRODUCT
+#define UF2_BOARD_ID      "STM32F303 discovery"
+#define UF2_VOLUME_LABEL  "F303BOOT"
+#define UF2_INDEX_URL     "https://www.st.com/en/evaluation-tools/stm32f3discovery.html"
+
+//--------------------------------------------------------------------+
+// UART
+//--------------------------------------------------------------------+
+
+#define UART_DEV              USART1
+#define UART_CLOCK_ENABLE     __HAL_RCC_USART1_CLK_ENABLE
+#define UART_GPIO_PORT        GPIOC
+#define UART_GPIO_AF          GPIO_AF7_USART1
+#define UART_TX_PIN           GPIO_PIN_4
+#define UART_RX_PIN           GPIO_PIN_5
+
+//--------------------------------------------------------------------+
+// RCC Clock
+//--------------------------------------------------------------------+
+static inline void clock_init(void)
+{
+  RCC_ClkInitTypeDef RCC_ClkInitStruct;
+  RCC_OscInitTypeDef RCC_OscInitStruct;
+  RCC_PeriphCLKInitTypeDef  RCC_PeriphClkInit;
+
+  /* Enable HSE Oscillator and activate PLL with HSE as source */
+  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
+  RCC_OscInitStruct.HSEState = RCC_HSE_ON;
+  RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
+  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
+  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
+  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
+  HAL_RCC_OscConfig(&RCC_OscInitStruct);
+
+  HAL_RCCEx_GetPeriphCLKConfig(&RCC_PeriphClkInit);
+  RCC_PeriphClkInit.USBClockSelection = RCC_USBCLKSOURCE_PLL_DIV1_5;
+  HAL_RCCEx_PeriphCLKConfig(&RCC_PeriphClkInit);
+
+  /* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2
+  clocks dividers */
+  RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
+  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
+  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
+  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
+  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
+  HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2);
+
+  /* Enable Power Clock */
+  __HAL_RCC_PWR_CLK_ENABLE();
+}
+
+#endif
diff --git a/ports/stm32f3/boards/stm32f303disco/board.mk b/ports/stm32f3/boards/stm32f303disco/board.mk
new file mode 100644
index 0000000..90403f5
--- /dev/null
+++ b/ports/stm32f3/boards/stm32f303disco/board.mk
@@ -0,0 +1,12 @@
+CFLAGS += \
+  -DSTM32F303xC \
+  -DHSE_VALUE=8000000U
+
+SRC_S += \
+  $(ST_CMSIS)/Source/Templates/gcc/startup_stm32f303xc.s
+
+# For flash-jlink target
+JLINK_DEVICE = stm32f303vc
+
+flash: flash-stlink
+erase: erase-stlink
diff --git a/ports/stm32f3/linker/STM32F303VCTx_FLASH.ld b/ports/stm32f3/linker/STM32F303VCTx_FLASH.ld
new file mode 100644
index 0000000..d1f8268
--- /dev/null
+++ b/ports/stm32f3/linker/STM32F303VCTx_FLASH.ld
@@ -0,0 +1,188 @@
+/*
+*****************************************************************************
+**
+
+**  File        : LinkerScript.ld
+**
+**  Abstract    : Linker script for STM32F303VCTx Device with
+**                256KByte FLASH, 40KByte RAM
+**
+**                Set heap size, stack size and stack location according
+**                to application requirements.
+**
+**                Set memory bank area and size if external memory is used.
+**
+**  Target      : STMicroelectronics STM32
+**
+**
+**  Distribution: The file is distributed as is, without any warranty
+**                of any kind.
+**
+**  (c)Copyright Ac6.
+**  You may use this file as-is or modify it according to the needs of your
+**  project. Distribution of this file (unmodified or modified) is not
+**  permitted. Ac6 permit registered System Workbench for MCU users the
+**  rights to distribute the assembled, compiled & linked contents of this
+**  file as part of an application binary file, provided that it is built
+**  using the System Workbench for MCU toolchain.
+**
+*****************************************************************************
+*/
+
+/* Entry Point */
+ENTRY(Reset_Handler)
+
+/* Highest address of the user mode stack */
+_estack = ORIGIN(RAM) + LENGTH(RAM);     /* end of RAM */
+_board_dfu_dbl_tap = _estack;
+/* Generate a link error if heap and stack don't fit into RAM */
+_Min_Heap_Size = 0x800;;      /* required amount of heap  */
+_Min_Stack_Size = 0x800;; /* required amount of stack */
+
+/* Specify the memory areas */
+MEMORY
+{
+FLASH (rx)      : ORIGIN = 0x8000000, LENGTH = 256K
+RAM (xrw)      : ORIGIN = 0x20000000, LENGTH = 40K - 4
+CCMRAM (rw)      : ORIGIN = 0x10000000, LENGTH = 8K
+}
+
+/* Define output sections */
+SECTIONS
+{
+  /* The startup code goes first into FLASH */
+  .isr_vector :
+  {
+    . = ALIGN(4);
+    KEEP(*(.isr_vector)) /* Startup code */
+    . = ALIGN(4);
+  } >FLASH
+
+  /* The program code and other data goes into FLASH */
+  .text :
+  {
+    . = ALIGN(4);
+    *(.text)           /* .text sections (code) */
+    *(.text*)          /* .text* sections (code) */
+    *(.glue_7)         /* glue arm to thumb code */
+    *(.glue_7t)        /* glue thumb to arm code */
+    *(.eh_frame)
+
+    KEEP (*(.init))
+    KEEP (*(.fini))
+
+    . = ALIGN(4);
+    _etext = .;        /* define a global symbols at end of code */
+  } >FLASH
+
+  /* Constant data goes into FLASH */
+  .rodata :
+  {
+    . = ALIGN(4);
+    *(.rodata)         /* .rodata sections (constants, strings, etc.) */
+    *(.rodata*)        /* .rodata* sections (constants, strings, etc.) */
+    . = ALIGN(4);
+  } >FLASH
+
+  .ARM.extab   : { *(.ARM.extab* .gnu.linkonce.armextab.*) } >FLASH
+  .ARM : {
+    __exidx_start = .;
+    *(.ARM.exidx*)
+    __exidx_end = .;
+  } >FLASH
+
+  .preinit_array     :
+  {
+    PROVIDE_HIDDEN (__preinit_array_start = .);
+    KEEP (*(.preinit_array*))
+    PROVIDE_HIDDEN (__preinit_array_end = .);
+  } >FLASH
+  .init_array :
+  {
+    PROVIDE_HIDDEN (__init_array_start = .);
+    KEEP (*(SORT(.init_array.*)))
+    KEEP (*(.init_array*))
+    PROVIDE_HIDDEN (__init_array_end = .);
+  } >FLASH
+  .fini_array :
+  {
+    PROVIDE_HIDDEN (__fini_array_start = .);
+    KEEP (*(SORT(.fini_array.*)))
+    KEEP (*(.fini_array*))
+    PROVIDE_HIDDEN (__fini_array_end = .);
+  } >FLASH
+
+  /* used by the startup to initialize data */
+  _sidata = LOADADDR(.data);
+
+  /* Initialized data sections goes into RAM, load LMA copy after code */
+  .data :
+  {
+    . = ALIGN(4);
+    _sdata = .;        /* create a global symbol at data start */
+    *(.data)           /* .data sections */
+    *(.data*)          /* .data* sections */
+
+    . = ALIGN(4);
+    _edata = .;        /* define a global symbol at data end */
+  } >RAM AT> FLASH
+
+  _siccmram = LOADADDR(.ccmram);
+
+  /* CCM-RAM section
+  *
+  * IMPORTANT NOTE!
+  * If initialized variables will be placed in this section,
+  * the startup code needs to be modified to copy the init-values.
+  */
+  .ccmram :
+  {
+    . = ALIGN(4);
+    _sccmram = .;       /* create a global symbol at ccmram start */
+    *(.ccmram)
+    *(.ccmram*)
+
+    . = ALIGN(4);
+    _eccmram = .;       /* create a global symbol at ccmram end */
+  } >CCMRAM AT> FLASH
+
+
+  /* Uninitialized data section */
+  . = ALIGN(4);
+  .bss :
+  {
+    /* This is used by the startup in order to initialize the .bss secion */
+    _sbss = .;         /* define a global symbol at bss start */
+    __bss_start__ = _sbss;
+    *(.bss)
+    *(.bss*)
+    *(COMMON)
+
+    . = ALIGN(4);
+    _ebss = .;         /* define a global symbol at bss end */
+    __bss_end__ = _ebss;
+  } >RAM
+
+  /* User_heap_stack section, used to check that there is enough RAM left */
+  ._user_heap_stack :
+  {
+    . = ALIGN(8);
+    PROVIDE ( end = . );
+    PROVIDE ( _end = . );
+    . = . + _Min_Heap_Size;
+    . = . + _Min_Stack_Size;
+    . = ALIGN(8);
+  } >RAM
+
+
+
+  /* Remove information from the standard libraries */
+  /DISCARD/ :
+  {
+    libc.a ( * )
+    libm.a ( * )
+    libgcc.a ( * )
+  }
+
+  .ARM.attributes 0 : { *(.ARM.attributes) }
+}
diff --git a/ports/stm32f3/stm32f3xx_hal_conf.h b/ports/stm32f3/stm32f3xx_hal_conf.h
new file mode 100644
index 0000000..8915708
--- /dev/null
+++ b/ports/stm32f3/stm32f3xx_hal_conf.h
@@ -0,0 +1,360 @@
+/**
+  ******************************************************************************
+  * @file    stm32f3xx_hal_conf.h
+  * @brief   HAL configuration file.
+  ******************************************************************************
+  * @attention
+  *
+  * <h2><center>&copy; Copyright (c) 2016 STMicroelectronics.
+  * All rights reserved.</center></h2>
+  *
+  * This software component is licensed by ST under BSD 3-Clause license,
+  * the "License"; You may not use this file except in compliance with the
+  * License. You may obtain a copy of the License at:
+  *                        opensource.org/licenses/BSD-3-Clause
+  *
+  ******************************************************************************
+  */
+
+/* Define to prevent recursive inclusion -------------------------------------*/
+#ifndef __STM32F3xx_HAL_CONF_H
+#define __STM32F3xx_HAL_CONF_H
+
+#ifdef __cplusplus
+ extern "C" {
+#endif
+
+/* Exported types ------------------------------------------------------------*/
+/* Exported constants --------------------------------------------------------*/
+
+/* ########################## Module Selection ############################## */
+/**
+  * @brief This is the list of modules to be used in the HAL driver
+  */
+
+#define HAL_MODULE_ENABLED
+  /*#define HAL_ADC_MODULE_ENABLED   */
+/*#define HAL_CRYP_MODULE_ENABLED   */
+/*#define HAL_CAN_MODULE_ENABLED   */
+/*#define HAL_CEC_MODULE_ENABLED   */
+/*#define HAL_NAND_MODULE_ENABLED   */
+/*#define HAL_NOR_MODULE_ENABLED   */
+/*#define HAL_PCCARD_MODULE_ENABLED   */
+/*#define HAL_SRAM_MODULE_ENABLED   */
+/*#define HAL_HRTIM_MODULE_ENABLED   */
+/*#define HAL_OPAMP_MODULE_ENABLED   */
+/*#define HAL_SDADC_MODULE_ENABLED   */
+/*#define HAL_TSC_MODULE_ENABLED   */
+/*#define HAL_COMP_MODULE_ENABLED   */
+/*#define HAL_CRC_MODULE_ENABLED   */
+/*#define HAL_CRYP_MODULE_ENABLED   */
+/*#define HAL_DAC_MODULE_ENABLED   */
+/*#define HAL_I2S_MODULE_ENABLED   */
+/*#define HAL_IWDG_MODULE_ENABLED   */
+/*#define HAL_LCD_MODULE_ENABLED   */
+/*#define HAL_LPTIM_MODULE_ENABLED   */
+/*#define HAL_RNG_MODULE_ENABLED   */
+/*#define HAL_RTC_MODULE_ENABLED   */
+//#define HAL_SPI_MODULE_ENABLED
+/*#define HAL_TIM_MODULE_ENABLED   */
+#define HAL_UART_MODULE_ENABLED
+/*#define HAL_USART_MODULE_ENABLED   */
+/*#define HAL_IRDA_MODULE_ENABLED   */
+/*#define HAL_SMARTCARD_MODULE_ENABLED   */
+/*#define HAL_SMBUS_MODULE_ENABLED   */
+/*#define HAL_WWDG_MODULE_ENABLED   */
+#define HAL_PCD_MODULE_ENABLED
+#define HAL_GPIO_MODULE_ENABLED
+#define HAL_EXTI_MODULE_ENABLED
+/* #define HAL_CAN_LEGACY_MODULE_ENABLED */
+#define HAL_DMA_MODULE_ENABLED
+#define HAL_RCC_MODULE_ENABLED
+#define HAL_FLASH_MODULE_ENABLED
+#define HAL_PWR_MODULE_ENABLED
+#define HAL_CORTEX_MODULE_ENABLED
+//#define HAL_I2C_MODULE_ENABLED
+/* ########################## HSE/HSI Values adaptation ##################### */
+/**
+  * @brief Adjust the value of External High Speed oscillator (HSE) used in your application.
+  *        This value is used by the RCC HAL module to compute the system frequency
+  *        (when HSE is used as system clock source, directly or through the PLL).
+  */
+#if !defined  (HSE_VALUE)
+  #define HSE_VALUE    ((uint32_t)8000000) /*!< Value of the External oscillator in Hz */
+#endif /* HSE_VALUE */
+
+/**
+  * @brief In the following line adjust the External High Speed oscillator (HSE) Startup
+  *        Timeout value
+  */
+#if !defined  (HSE_STARTUP_TIMEOUT)
+  #define HSE_STARTUP_TIMEOUT    ((uint32_t)100)   /*!< Time out for HSE start up, in ms */
+#endif /* HSE_STARTUP_TIMEOUT */
+
+/**
+  * @brief Internal High Speed oscillator (HSI) value.
+  *        This value is used by the RCC HAL module to compute the system frequency
+  *        (when HSI is used as system clock source, directly or through the PLL).
+  */
+#if !defined  (HSI_VALUE)
+  #define HSI_VALUE    ((uint32_t)8000000) /*!< Value of the Internal oscillator in Hz*/
+#endif /* HSI_VALUE */
+
+/**
+  * @brief In the following line adjust the Internal High Speed oscillator (HSI) Startup
+  *        Timeout value
+  */
+#if !defined  (HSI_STARTUP_TIMEOUT)
+ #define HSI_STARTUP_TIMEOUT   ((uint32_t)5000) /*!< Time out for HSI start up */
+#endif /* HSI_STARTUP_TIMEOUT */
+
+/**
+  * @brief Internal Low Speed oscillator (LSI) value.
+  */
+#if !defined  (LSI_VALUE)
+ #define LSI_VALUE  ((uint32_t)40000)
+#endif /* LSI_VALUE */                      /*!< Value of the Internal Low Speed oscillator in Hz
+                                             The real value may vary depending on the variations
+                                             in voltage and temperature.  */
+/**
+  * @brief External Low Speed oscillator (LSE) value.
+  */
+#if !defined  (LSE_VALUE)
+ #define LSE_VALUE  ((uint32_t)32768)    /*!< Value of the External Low Speed oscillator in Hz */
+#endif /* LSE_VALUE */
+
+/**
+  * @brief Time out for LSE start up value in ms.
+  */
+#if !defined  (LSE_STARTUP_TIMEOUT)
+  #define LSE_STARTUP_TIMEOUT    ((uint32_t)5000)   /*!< Time out for LSE start up, in ms */
+#endif /* LSE_STARTUP_TIMEOUT */
+
+/**
+  * @brief External clock source for I2S peripheral
+  *        This value is used by the I2S HAL module to compute the I2S clock source
+  *        frequency, this source is inserted directly through I2S_CKIN pad.
+  *        - External clock generated through external PLL component on EVAL 303 (based on MCO or crystal)
+  *        - External clock not generated on EVAL 373
+  */
+#if !defined  (EXTERNAL_CLOCK_VALUE)
+  #define EXTERNAL_CLOCK_VALUE    ((uint32_t)8000000) /*!< Value of the External oscillator in Hz*/
+#endif /* EXTERNAL_CLOCK_VALUE */
+
+/* Tip: To avoid modifying this file each time you need to use different HSE,
+   ===  you can define the HSE value in your toolchain compiler preprocessor. */
+
+/* ########################### System Configuration ######################### */
+/**
+  * @brief This is the HAL system configuration section
+  */
+
+#define  VDD_VALUE                   ((uint32_t)3300) /*!< Value of VDD in mv */
+#define  TICK_INT_PRIORITY            ((uint32_t)0)    /*!< tick interrupt priority (lowest by default)  */
+#define  USE_RTOS                     0
+#define  PREFETCH_ENABLE              1
+#define  INSTRUCTION_CACHE_ENABLE     1
+#define  DATA_CACHE_ENABLE            1
+#define USE_SPI_CRC                     0U
+
+#define  USE_HAL_ADC_REGISTER_CALLBACKS         0U /* ADC register callback disabled       */
+#define  USE_HAL_CAN_REGISTER_CALLBACKS         0U /* CAN register callback disabled       */
+#define  USE_HAL_COMP_REGISTER_CALLBACKS        0U /* COMP register callback disabled      */
+#define  USE_HAL_CEC_REGISTER_CALLBACKS         0U /* CEC register callback disabled       */
+#define  USE_HAL_DAC_REGISTER_CALLBACKS         0U /* DAC register callback disabled       */
+#define  USE_HAL_SRAM_REGISTER_CALLBACKS        0U /* SRAM register callback disabled      */
+#define  USE_HAL_SMBUS_REGISTER_CALLBACKS       0U /* SMBUS register callback disabled     */
+#define  USE_HAL_NAND_REGISTER_CALLBACKS        0U /* NAND register callback disabled      */
+#define  USE_HAL_NOR_REGISTER_CALLBACKS         0U /* NOR register callback disabled       */
+#define  USE_HAL_PCCARD_REGISTER_CALLBACKS      0U /* PCCARD register callback disabled    */
+#define  USE_HAL_HRTIM_REGISTER_CALLBACKS       0U /* HRTIM register callback disabled     */
+#define  USE_HAL_I2C_REGISTER_CALLBACKS         0U /* I2C register callback disabled       */
+#define  USE_HAL_UART_REGISTER_CALLBACKS        0U /* UART register callback disabled      */
+#define  USE_HAL_USART_REGISTER_CALLBACKS       0U /* USART register callback disabled     */
+#define  USE_HAL_IRDA_REGISTER_CALLBACKS        0U /* IRDA register callback disabled      */
+#define  USE_HAL_SMARTCARD_REGISTER_CALLBACKS   0U /* SMARTCARD register callback disabled */
+#define  USE_HAL_WWDG_REGISTER_CALLBACKS        0U /* WWDG register callback disabled      */
+#define  USE_HAL_OPAMP_REGISTER_CALLBACKS       0U /* OPAMP register callback disabled     */
+#define  USE_HAL_RTC_REGISTER_CALLBACKS         0U /* RTC register callback disabled       */
+#define  USE_HAL_SPI_REGISTER_CALLBACKS         0U /* SPI register callback disabled       */
+#define  USE_HAL_I2S_REGISTER_CALLBACKS         0U /* I2S register callback disabled       */
+#define  USE_HAL_TIM_REGISTER_CALLBACKS         0U /* TIM register callback disabled       */
+#define  USE_HAL_TSC_REGISTER_CALLBACKS         0U /* TSC register callback disabled       */
+#define  USE_HAL_PCD_REGISTER_CALLBACKS         0U /* PCD register callback disabled       */
+
+/* ########################## Assert Selection ############################## */
+/**
+  * @brief Uncomment the line below to expanse the "assert_param" macro in the
+  *        HAL drivers code
+  */
+/* #define USE_FULL_ASSERT    1U */
+
+/* Includes ------------------------------------------------------------------*/
+/**
+  * @brief Include module's header file
+  */
+
+#ifdef HAL_RCC_MODULE_ENABLED
+ #include "stm32f3xx_hal_rcc.h"
+#endif /* HAL_RCC_MODULE_ENABLED */
+
+#ifdef HAL_GPIO_MODULE_ENABLED
+ #include "stm32f3xx_hal_gpio.h"
+#endif /* HAL_GPIO_MODULE_ENABLED */
+
+#ifdef HAL_EXTI_MODULE_ENABLED
+  #include "stm32f3xx_hal_exti.h"
+#endif /* HAL_EXTI_MODULE_ENABLED */
+
+#ifdef HAL_DMA_MODULE_ENABLED
+  #include "stm32f3xx_hal_dma.h"
+#endif /* HAL_DMA_MODULE_ENABLED */
+
+#ifdef HAL_CORTEX_MODULE_ENABLED
+ #include "stm32f3xx_hal_cortex.h"
+#endif /* HAL_CORTEX_MODULE_ENABLED */
+
+#ifdef HAL_ADC_MODULE_ENABLED
+ #include "stm32f3xx_hal_adc.h"
+#endif /* HAL_ADC_MODULE_ENABLED */
+
+#ifdef HAL_CAN_MODULE_ENABLED
+ #include "stm32f3xx_hal_can.h"
+#endif /* HAL_CAN_MODULE_ENABLED */
+
+#ifdef HAL_CAN_LEGACY_MODULE_ENABLED
+  #include "stm32f3xx_hal_can_legacy.h"
+#endif /* HAL_CAN_LEGACY_MODULE_ENABLED */
+
+#ifdef HAL_CEC_MODULE_ENABLED
+ #include "stm32f3xx_hal_cec.h"
+#endif /* HAL_CEC_MODULE_ENABLED */
+
+#ifdef HAL_COMP_MODULE_ENABLED
+ #include "stm32f3xx_hal_comp.h"
+#endif /* HAL_COMP_MODULE_ENABLED */
+
+#ifdef HAL_CRC_MODULE_ENABLED
+ #include "stm32f3xx_hal_crc.h"
+#endif /* HAL_CRC_MODULE_ENABLED */
+
+#ifdef HAL_DAC_MODULE_ENABLED
+ #include "stm32f3xx_hal_dac.h"
+#endif /* HAL_DAC_MODULE_ENABLED */
+
+#ifdef HAL_FLASH_MODULE_ENABLED
+ #include "stm32f3xx_hal_flash.h"
+#endif /* HAL_FLASH_MODULE_ENABLED */
+
+#ifdef HAL_SRAM_MODULE_ENABLED
+  #include "stm32f3xx_hal_sram.h"
+#endif /* HAL_SRAM_MODULE_ENABLED */
+
+#ifdef HAL_NOR_MODULE_ENABLED
+  #include "stm32f3xx_hal_nor.h"
+#endif /* HAL_NOR_MODULE_ENABLED */
+
+#ifdef HAL_NAND_MODULE_ENABLED
+  #include "stm32f3xx_hal_nand.h"
+#endif /* HAL_NAND_MODULE_ENABLED */
+
+#ifdef HAL_PCCARD_MODULE_ENABLED
+  #include "stm32f3xx_hal_pccard.h"
+#endif /* HAL_PCCARD_MODULE_ENABLED */
+
+#ifdef HAL_HRTIM_MODULE_ENABLED
+ #include "stm32f3xx_hal_hrtim.h"
+#endif /* HAL_HRTIM_MODULE_ENABLED */
+
+#ifdef HAL_I2C_MODULE_ENABLED
+ #include "stm32f3xx_hal_i2c.h"
+#endif /* HAL_I2C_MODULE_ENABLED */
+
+#ifdef HAL_I2S_MODULE_ENABLED
+ #include "stm32f3xx_hal_i2s.h"
+#endif /* HAL_I2S_MODULE_ENABLED */
+
+#ifdef HAL_IRDA_MODULE_ENABLED
+ #include "stm32f3xx_hal_irda.h"
+#endif /* HAL_IRDA_MODULE_ENABLED */
+
+#ifdef HAL_IWDG_MODULE_ENABLED
+ #include "stm32f3xx_hal_iwdg.h"
+#endif /* HAL_IWDG_MODULE_ENABLED */
+
+#ifdef HAL_OPAMP_MODULE_ENABLED
+ #include "stm32f3xx_hal_opamp.h"
+#endif /* HAL_OPAMP_MODULE_ENABLED */
+
+#ifdef HAL_PCD_MODULE_ENABLED
+ #include "stm32f3xx_hal_pcd.h"
+#endif /* HAL_PCD_MODULE_ENABLED */
+
+#ifdef HAL_PWR_MODULE_ENABLED
+ #include "stm32f3xx_hal_pwr.h"
+#endif /* HAL_PWR_MODULE_ENABLED */
+
+#ifdef HAL_RTC_MODULE_ENABLED
+ #include "stm32f3xx_hal_rtc.h"
+#endif /* HAL_RTC_MODULE_ENABLED */
+
+#ifdef HAL_SDADC_MODULE_ENABLED
+ #include "stm32f3xx_hal_sdadc.h"
+#endif /* HAL_SDADC_MODULE_ENABLED */
+
+#ifdef HAL_SMARTCARD_MODULE_ENABLED
+ #include "stm32f3xx_hal_smartcard.h"
+#endif /* HAL_SMARTCARD_MODULE_ENABLED */
+
+#ifdef HAL_SMBUS_MODULE_ENABLED
+ #include "stm32f3xx_hal_smbus.h"
+#endif /* HAL_SMBUS_MODULE_ENABLED */
+
+#ifdef HAL_SPI_MODULE_ENABLED
+ #include "stm32f3xx_hal_spi.h"
+#endif /* HAL_SPI_MODULE_ENABLED */
+
+#ifdef HAL_TIM_MODULE_ENABLED
+ #include "stm32f3xx_hal_tim.h"
+#endif /* HAL_TIM_MODULE_ENABLED */
+
+#ifdef HAL_TSC_MODULE_ENABLED
+ #include "stm32f3xx_hal_tsc.h"
+#endif /* HAL_TSC_MODULE_ENABLED */
+
+#ifdef HAL_UART_MODULE_ENABLED
+ #include "stm32f3xx_hal_uart.h"
+#endif /* HAL_UART_MODULE_ENABLED */
+
+#ifdef HAL_USART_MODULE_ENABLED
+ #include "stm32f3xx_hal_usart.h"
+#endif /* HAL_USART_MODULE_ENABLED */
+
+#ifdef HAL_WWDG_MODULE_ENABLED
+ #include "stm32f3xx_hal_wwdg.h"
+#endif /* HAL_WWDG_MODULE_ENABLED */
+
+/* Exported macro ------------------------------------------------------------*/
+#ifdef  USE_FULL_ASSERT
+/**
+  * @brief  The assert_param macro is used for function's parameters check.
+  * @param  expr If expr is false, it calls assert_failed function
+  *         which reports the name of the source file and the source
+  *         line number of the call that failed.
+  *         If expr is true, it returns no value.
+  * @retval None
+  */
+  #define assert_param(expr) ((expr) ? (void)0U : assert_failed((uint8_t *)__FILE__, __LINE__))
+/* Exported functions ------------------------------------------------------- */
+  void assert_failed(uint8_t* file, uint32_t line);
+#else
+  #define assert_param(expr) ((void)0U)
+#endif /* USE_FULL_ASSERT */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __STM32F3xx_HAL_CONF_H */
+
+/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
diff --git a/ports/stm32f3/tusb_config.h b/ports/stm32f3/tusb_config.h
new file mode 100644
index 0000000..69cfa2a
--- /dev/null
+++ b/ports/stm32f3/tusb_config.h
@@ -0,0 +1,95 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Ha Thach (tinyusb.org)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ */
+
+#ifndef _TUSB_CONFIG_H_
+#define _TUSB_CONFIG_H_
+
+#ifdef __cplusplus
+ extern "C" {
+#endif
+
+//--------------------------------------------------------------------
+// COMMON CONFIGURATION
+//--------------------------------------------------------------------
+
+// defined by board.mk
+#ifndef CFG_TUSB_MCU
+  #error CFG_TUSB_MCU must be defined
+#endif
+
+// RHPort number used for device can be defined by board.mk, default to port 0
+#ifndef BOARD_DEVICE_RHPORT_NUM
+  #define BOARD_DEVICE_RHPORT_NUM     0
+#endif
+
+// RHPort max operational speed can defined by board.mk
+// Default to Highspeed for MCU with internal HighSpeed PHY (can be port specific), otherwise FullSpeed
+#define CFG_TUSB_RHPORT0_MODE      OPT_MODE_DEVICE
+
+// This example doesn't use an RTOS
+#define CFG_TUSB_OS               OPT_OS_NONE
+
+// CFG_TUSB_DEBUG is defined by compiler in DEBUG build
+// #define CFG_TUSB_DEBUG           0
+
+/* USB DMA on some MCUs can only access a specific SRAM region with restriction on alignment.
+ * Tinyusb use follows macros to declare transferring memory so that they can be put
+ * into those specific section.
+ * e.g
+ * - CFG_TUSB_MEM SECTION : __attribute__ (( section(".usb_ram") ))
+ * - CFG_TUSB_MEM_ALIGN   : __attribute__ ((aligned(4)))
+ */
+#ifndef CFG_TUSB_MEM_SECTION
+#define CFG_TUSB_MEM_SECTION
+#endif
+
+#ifndef CFG_TUSB_MEM_ALIGN
+#define CFG_TUSB_MEM_ALIGN          __attribute__ ((aligned(4)))
+#endif
+
+//--------------------------------------------------------------------
+// DEVICE CONFIGURATION
+//--------------------------------------------------------------------
+
+#ifndef CFG_TUD_ENDPOINT0_SIZE
+#define CFG_TUD_ENDPOINT0_SIZE    64
+#endif
+
+//------------- CLASS -------------//
+#define CFG_TUD_CDC               0
+#define CFG_TUD_MSC               1
+#define CFG_TUD_HID               1
+#define CFG_TUD_MIDI              0
+#define CFG_TUD_VENDOR            0
+
+// MSC Buffer size of Device Mass storage
+#define CFG_TUD_MSC_BUFSIZE     512
+#define CFG_TUD_HID_BUFSIZE      64
+
+#ifdef __cplusplus
+ }
+#endif
+
+#endif /* _TUSB_CONFIG_H_ */