diff --git a/hw/bsp/feather_stm32f405/board.mk b/hw/bsp/feather_stm32f405/board.mk
index ef977797..14595e83 100644
--- a/hw/bsp/feather_stm32f405/board.mk
+++ b/hw/bsp/feather_stm32f405/board.mk
@@ -20,7 +20,8 @@ SRC_C += \
 	$(ST_HAL_DRIVER)/Src/stm32f4xx_hal.c \
 	$(ST_HAL_DRIVER)/Src/stm32f4xx_hal_cortex.c \
 	$(ST_HAL_DRIVER)/Src/stm32f4xx_hal_rcc.c \
-	$(ST_HAL_DRIVER)/Src/stm32f4xx_hal_gpio.c
+	$(ST_HAL_DRIVER)/Src/stm32f4xx_hal_gpio.c \
+	$(ST_HAL_DRIVER)/Src/stm32f4xx_hal_uart.c
 
 SRC_S += \
 	$(ST_CMSIS)/Source/Templates/gcc/startup_stm32f405xx.s
@@ -46,5 +47,5 @@ JLINK_IF = swd
 STM32Prog = STM32_Programmer_CLI
 
 # flash target using on-board stlink
-flash: $(BUILD)/$(BOARD)-firmware.elf
-	$(STM32Prog) --connect port=swd --write $< --go
+flash: $(BUILD)/$(BOARD)-firmware.bin
+	dfu-util -R -a 0 --dfuse-address 0x08000000 -D $<
diff --git a/hw/bsp/feather_stm32f405/feather_stm32f405.c b/hw/bsp/feather_stm32f405/feather_stm32f405.c
index 0bc40ece..aec779ea 100644
--- a/hw/bsp/feather_stm32f405/feather_stm32f405.c
+++ b/hw/bsp/feather_stm32f405/feather_stm32f405.c
@@ -31,7 +31,7 @@
 
 // Blue LED is chosen because the other LEDs are connected to ST-LINK lines.
 #define LED_PORT              GPIOC
-#define LED_PIN               GPIO_PIN_4
+#define LED_PIN               GPIO_PIN_1
 #define LED_STATE_ON          1
 
 // Pin D5
@@ -39,6 +39,24 @@
 #define BUTTON_PIN            GPIO_PIN_7
 #define BUTTON_STATE_ACTIVE   0
 
+#define UARTx                 USART3
+#define UART_GPIO_PORT        GPIOB
+#define UART_GPIO_AF          GPIO_AF7_USART3
+#define UART_TX_PIN           GPIO_PIN_10
+#define UART_RX_PIN           GPIO_PIN_11
+
+UART_HandleTypeDef UartHandle;
+
+
+// enable all LED, Button, Uart, USB clock
+static void all_rcc_clk_enable(void)
+{
+  __HAL_RCC_GPIOA_CLK_ENABLE();  // USB D+, D-
+  __HAL_RCC_GPIOC_CLK_ENABLE();  // LED, Button
+  __HAL_RCC_GPIOB_CLK_ENABLE();  // Uart tx, rx
+  __HAL_RCC_USART3_CLK_ENABLE(); // Uart module
+}
+
 /**
   * @brief  System Clock Configuration
   *         The system Clock is configured as follow :
@@ -104,14 +122,13 @@ void board_init(void)
 #endif
 
   SystemClock_Config();
-
-  // Notify runtime of frequency change.
   SystemCoreClockUpdate();
 
+  all_rcc_clk_enable();
+
   GPIO_InitTypeDef  GPIO_InitStruct;
 
   // LED
-  __HAL_RCC_GPIOC_CLK_ENABLE();
   GPIO_InitStruct.Pin = LED_PIN;
   GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
   GPIO_InitStruct.Pull = GPIO_PULLUP;
@@ -121,19 +138,25 @@ void board_init(void)
   board_led_write(false);
 
   // Button
-  //__HAL_RCC_GPIOC_CLK_ENABLE();
   GPIO_InitStruct.Pin = BUTTON_PIN;
   GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
   GPIO_InitStruct.Pull = GPIO_PULLUP;
   GPIO_InitStruct.Speed = GPIO_SPEED_FAST;
   HAL_GPIO_Init(BUTTON_PORT, &GPIO_InitStruct);
 
+  // Uart
+  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 = UART_GPIO_AF;
+  HAL_GPIO_Init(UART_GPIO_PORT, &GPIO_InitStruct);
+
   // Enable USB OTG clock
   __HAL_RCC_USB_OTG_FS_CLK_ENABLE();
 
   // USB Pin Init
   // PA9- VUSB, PA10- ID, PA11- DM, PA12- DP
-  __HAL_RCC_GPIOA_CLK_ENABLE();
 
   /* Configure DM DP Pins */
   GPIO_InitStruct.Pin = GPIO_PIN_11 | GPIO_PIN_12;
@@ -180,8 +203,8 @@ int board_uart_read(uint8_t* buf, int len)
 
 int board_uart_write(void const * buf, int len)
 {
-  (void) buf; (void) len;
-  return 0;
+  HAL_UART_Transmit(&UartHandle, (uint8_t*) buf, len, 0xffff);
+  return len;
 }
 
 #if CFG_TUSB_OS  == OPT_OS_NONE
diff --git a/hw/bsp/feather_stm32f405/stm32f4xx_hal_conf.h b/hw/bsp/feather_stm32f405/stm32f4xx_hal_conf.h
index dbef20e0..b892df3b 100644
--- a/hw/bsp/feather_stm32f405/stm32f4xx_hal_conf.h
+++ b/hw/bsp/feather_stm32f405/stm32f4xx_hal_conf.h
@@ -75,7 +75,7 @@
 /* #define HAL_MMC_MODULE_ENABLED   */
 /* #define HAL_SPI_MODULE_ENABLED   */
 /* #define HAL_TIM_MODULE_ENABLED   */
-/* #define HAL_UART_MODULE_ENABLED   */
+#define HAL_UART_MODULE_ENABLED
 /* #define HAL_USART_MODULE_ENABLED   */
 /* #define HAL_IRDA_MODULE_ENABLED   */
 /* #define HAL_SMARTCARD_MODULE_ENABLED   */
@@ -199,6 +199,8 @@
 #define  USE_HAL_SPI_REGISTER_CALLBACKS     0U /* SPI register callback disabled     */
 #define  USE_HAL_SWPMI_REGISTER_CALLBACKS   0U /* SWPMI register callback disabled   */
 #define  USE_HAL_TIM_REGISTER_CALLBACKS     0U /* TIM 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_WWDG_REGISTER_CALLBACKS    0U /* WWDG register callback disabled    */
 
 /* ########################## Assert Selection ############################## */
diff --git a/hw/bsp/stm32f072disco/stm32f072disco.c b/hw/bsp/stm32f072disco/stm32f072disco.c
index aac1c553..e26c5628 100644
--- a/hw/bsp/stm32f072disco/stm32f072disco.c
+++ b/hw/bsp/stm32f072disco/stm32f072disco.c
@@ -43,9 +43,9 @@
 #define UART_TX_PIN           GPIO_PIN_9
 #define UART_RX_PIN           GPIO_PIN_10
 
-
 UART_HandleTypeDef UartHandle;
 
+
 // enable all LED, Button, Uart, USB clock
 static void all_rcc_clk_enable(void)
 {