Update UARTs for stm32f4xx discovery boards. Other minor cleanups.

hw/bsp/stm32f411disco/board.mk

@@ -20,6 +20,7 @@ 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_uart.c \
 	$(ST_HAL_DRIVER)/Src/stm32f4xx_hal_gpio.c
 
 SRC_S += \

hw/bsp/stm32f411disco/stm32f411disco.c

@@ -28,6 +28,7 @@
 
 #include "stm32f4xx_hal.h"
 
+// Orange LED
 #define LED_PORT              GPIOD
 #define LED_PIN               GPIO_PIN_13
 #define LED_STATE_ON          1
@@ -36,11 +37,21 @@
 #define BUTTON_PIN            GPIO_PIN_0
 #define BUTTON_STATE_ACTIVE   1
 
+// Enable PA2 as the debug log UART
+#define UARTx                 USART2
+#define UART_GPIO_PORT        GPIOA
+#define UART_GPIO_AF          GPIO_AF7_USART2
+#define UART_TX_PIN           GPIO_PIN_2
+#define UART_RX_PIN           GPIO_PIN_3
+
+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-, Button
   __HAL_RCC_GPIOD_CLK_ENABLE();  // LED
+  __HAL_RCC_USART2_CLK_ENABLE(); // Uart module
 }
 
 /**
@@ -151,6 +162,25 @@ void board_init(void)
   GPIO_InitStruct.Alternate = GPIO_AF10_OTG_FS;
   HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 
+  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);
+
+  UartHandle = (UART_HandleTypeDef){
+    .Instance        = UARTx,
+    .Init.BaudRate   = CFG_BOARD_UART_BAUDRATE,
+    .Init.WordLength = UART_WORDLENGTH_8B,
+    .Init.StopBits   = UART_STOPBITS_1,
+    .Init.Parity     = UART_PARITY_NONE,
+    .Init.HwFlowCtl  = UART_HWCONTROL_NONE,
+    .Init.Mode       = UART_MODE_TX_RX,
+    .Init.OverSampling = UART_OVERSAMPLING_16
+  };
+  HAL_UART_Init(&UartHandle);
+
   // Enable USB OTG clock
   __HAL_RCC_USB_OTG_FS_CLK_ENABLE();
 
@@ -181,8 +211,8 @@ 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

hw/bsp/stm32f411disco/stm32f4xx_hal_conf.h

@@ -68,7 +68,7 @@
 /* #define HAL_SD_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 */