Enable dual USART output functionality.

In other words, enable the USART connected to the serial port on
the Raspberry Pi GPIO header.

Sending a newline to either USART directs the generated entropy
to that USART.

5 files changed, 75 insertions, 46 deletions

diff --git a/src/uart-test/main.c b/src/uart-test/main.c
index 77c17f4..55ec6fb 100644
--- a/src/uart-test/main.c
+++ b/src/uart-test/main.c
@@ -9,24 +9,45 @@
 
 #define DELAY() HAL_Delay(250)
 
+UART_HandleTypeDef *huart;
+
+/*
+ * If a newline is received on UART1 or UART2, redirect output to that UART.
+ */
+void check_uart_rx(UART_HandleTypeDef *this) {
+  uint8_t rx = 0;
+  if (HAL_UART_Receive(this, &rx, 1, 0) == HAL_OK) {
+    if (rx == '\n') {
+      HAL_GPIO_TogglePin(LED_PORT, LED_GREEN);
+
+      huart = this;
+    }
+  }
+}
+
 int
 main()
 {
   uint8_t c = 'a';
-  uint32_t i = 0;
 
   stm_init();
 
+  huart = &huart1;
+
   while (1)
   {
     HAL_GPIO_TogglePin(LED_PORT, LED_YELLOW);
 
-    HAL_UART_Transmit(&huart1, (uint8_t *) &c, 1, 0xff);
+    HAL_UART_Transmit(huart, (uint8_t *) &c, 1, 0xff);
     DELAY();
 
     if (c++ == 'z') {
       c = 'a';
       HAL_GPIO_TogglePin(LED_PORT, LED_BLUE);
     }
+
+    /* Check for UART change request */
+    check_uart_rx(&huart1);
+    check_uart_rx(&huart2);
   }
 }
diff --git a/src/uart-test/stm32f4xx_hal_msp.c b/src/uart-test/stm32f4xx_hal_msp.c
index 7cee9ce..4416195 100644
--- a/src/uart-test/stm32f4xx_hal_msp.c
+++ b/src/uart-test/stm32f4xx_hal_msp.c
@@ -5,6 +5,8 @@
  *
  *   PA9:  USART1_TX
  *   PA10: USART1_RX
+ *   PA2:  USART2_TX
+ *   PA3:  USART2_RX
  */
 
 #include "stm32f4xx_hal.h"
@@ -19,14 +21,19 @@ void HAL_UART_MspInit(UART_HandleTypeDef* huart)
     __USART1_CLK_ENABLE();
     GPIO_InitStruct.Pin = GPIO_PIN_9 | GPIO_PIN_10;
     GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
-    GPIO_InitStruct.Pull = GPIO_PULLUP;
+    GPIO_InitStruct.Pull = GPIO_NOPULL;
     GPIO_InitStruct.Speed = GPIO_SPEED_FAST;
     GPIO_InitStruct.Alternate = GPIO_AF7_USART1;
     HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
-
-    /* NVIC for interrupt mode */
-    HAL_NVIC_SetPriority(USART1_IRQn, 0, 1);
-    HAL_NVIC_EnableIRQ(USART1_IRQn);
+  } else if (huart->Instance == USART2) {
+    /* Peripheral clock enable */
+    __USART2_CLK_ENABLE();
+    GPIO_InitStruct.Pin = GPIO_PIN_2 | GPIO_PIN_3;
+    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
+    GPIO_InitStruct.Pull = GPIO_NOPULL;
+    GPIO_InitStruct.Speed = GPIO_SPEED_FAST;
+    GPIO_InitStruct.Alternate = GPIO_AF7_USART2;
+    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
   }
 
 }
@@ -37,6 +44,9 @@ void HAL_UART_MspDeInit(UART_HandleTypeDef* huart)
   if (huart->Instance == USART1) {
     __USART1_CLK_DISABLE();
     HAL_GPIO_DeInit(GPIOA, GPIO_PIN_9 | GPIO_PIN_10);
+  } else if (huart->Instance == USART2) {
+    __USART2_CLK_DISABLE();
+    HAL_GPIO_DeInit(GPIOA, GPIO_PIN_2 | GPIO_PIN_3);
   }
 
 }
diff --git a/src/uart-test/stm32f4xx_it.c b/src/uart-test/stm32f4xx_it.c
index 4e5bd89..73e7735 100644
--- a/src/uart-test/stm32f4xx_it.c
+++ b/src/uart-test/stm32f4xx_it.c
@@ -53,10 +53,6 @@
 /* Private define ------------------------------------------------------------*/
 /* Private macro -------------------------------------------------------------*/
 /* Private variables ---------------------------------------------------------*/
-
-/* UART handler declared in "stm_init.h" file */
-//extern UART_HandleTypeDef huart2;
-
 /* Private function prototypes -----------------------------------------------*/
 /* Private functions ---------------------------------------------------------*/
 
@@ -170,27 +166,6 @@ void SysTick_Handler(void)
 /******************************************************************************/
 
 /**
- * @brief  This function handles UART interrupt request.
- * @param  None
- * @retval None
- * @Note   This function is redefined in "main.h" and related to DMA stream
- *         used for USART data transmission
- */
-void USART1_IRQHandler(void)
-{
-  HAL_UART_IRQHandler(&huart1);
-}
-
-/**
-  * @brief  This function handles PPP interrupt request.
-  * @param  None
-  * @retval None
-  */
-/*void PPP_IRQHandler(void)
-{
-}*/
-
-/**
   * @}
   */
 
diff --git a/src/uart-test/stm_init.c b/src/uart-test/stm_init.c
index ad39080..384c4f8 100644
--- a/src/uart-test/stm_init.c
+++ b/src/uart-test/stm_init.c
@@ -40,11 +40,13 @@
 #include "stm_init.h"
 
 UART_HandleTypeDef huart1;
+UART_HandleTypeDef huart2;
 
 /* Private typedef -----------------------------------------------------------*/
 /* Private define ------------------------------------------------------------*/
 
 #define UART1_BAUD_RATE 460800
+#define UART2_BAUD_RATE 115200
 
 
 /* Private macro -------------------------------------------------------------*/
@@ -57,6 +59,7 @@ static void SystemClock_Config(void);
 static void Error_Handler(void);
 static void MX_GPIO_Init(void);
 static void MX_USART1_UART_Init(void);
+static void MX_USART2_UART_Init(void);
 /* Private functions ---------------------------------------------------------*/
 
 /**
@@ -89,6 +92,7 @@ void stm_init(void)
   /* Initialize all configured peripherals */
   MX_GPIO_Init();
   MX_USART1_UART_Init();
+  MX_USART2_UART_Init();
 }
 
 
@@ -138,8 +142,7 @@ static void SystemClock_Config(void)
   RCC_OscInitStruct.PLL.PLLN = 336;
   RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV8;
   RCC_OscInitStruct.PLL.PLLQ = 7;
-  if(HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
-  {
+  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
     Error_Handler();
   }
 
@@ -149,8 +152,7 @@ static void SystemClock_Config(void)
   RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;		/* AHB prescaler */
   RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;		/* APB1 prescaler /1 gives 42 MHz APB1 */
   RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;		/* APB2 prescaler /1 gives 42 MHz APB2 */
-  if(HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)
-  {
+  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK) {
     Error_Handler();
   }
 
@@ -179,11 +181,11 @@ void MX_GPIO_Init(void)
   __GPIOC_CLK_ENABLE();
 
   /*Configure LED GPIO pins PB12==red, PB13==yellow, PB14==green, PB15==blue */
-  GPIO_InitStruct.Pin = GPIO_PIN_12 | GPIO_PIN_13 | GPIO_PIN_14 | GPIO_PIN_15;
+  GPIO_InitStruct.Pin = LED_RED | LED_YELLOW | LED_GREEN | LED_BLUE;
   GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
   GPIO_InitStruct.Pull = GPIO_NOPULL;
   GPIO_InitStruct.Speed = GPIO_SPEED_LOW;
-  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
+  HAL_GPIO_Init(LED_PORT, &GPIO_InitStruct);
 
   /*Configure GPIO pin : PC9 (RCC_MCO_2) */
   GPIO_InitStruct.Pin = GPIO_PIN_9;
@@ -209,22 +211,42 @@ void MX_GPIO_Init(void)
 void MX_USART1_UART_Init(void)
 {
 
-  huart1.Instance = USART1;
-  huart1.Init.BaudRate = UART1_BAUD_RATE;
-  huart1.Init.WordLength = UART_WORDLENGTH_8B;
-  huart1.Init.StopBits = UART_STOPBITS_1;
-  huart1.Init.Parity = UART_PARITY_NONE;
-  huart1.Init.Mode = UART_MODE_TX_RX;
-  huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
+  huart1.Instance          = USART1;
+  huart1.Init.BaudRate     = UART1_BAUD_RATE;
+  huart1.Init.WordLength   = UART_WORDLENGTH_8B;
+  huart1.Init.StopBits     = UART_STOPBITS_1;
+  huart1.Init.Parity       = UART_PARITY_NONE;
+  huart1.Init.Mode         = UART_MODE_TX_RX;
+  huart1.Init.HwFlowCtl    = UART_HWCONTROL_NONE;
   huart1.Init.OverSampling = UART_OVERSAMPLING_16;
 
-  if(HAL_UART_Init(&huart1) != HAL_OK) {
+  if (HAL_UART_Init(&huart1) != HAL_OK) {
     /* Initialization Error */
     Error_Handler();
   }
 
 }
 
+/* USART2 init function */
+void MX_USART2_UART_Init(void)
+{
+
+  huart2.Instance          = USART2;
+  huart2.Init.BaudRate     = UART2_BAUD_RATE;
+  huart2.Init.WordLength   = UART_WORDLENGTH_8B;
+  huart2.Init.StopBits     = UART_STOPBITS_1;
+  huart2.Init.Parity       = UART_PARITY_NONE;
+  huart2.Init.Mode         = UART_MODE_TX_RX;
+  huart2.Init.HwFlowCtl    = UART_HWCONTROL_NONE;
+  huart2.Init.OverSampling = UART_OVERSAMPLING_16;
+
+  if (HAL_UART_Init(&huart2) != HAL_OK) {
+    /* Initialization Error */
+    Error_Handler();
+  }
+}
+
+
 /**
   * @brief  This function is executed in case of error occurrence.
   * @param  None
diff --git a/src/uart-test/stm_init.h b/src/uart-test/stm_init.h
index e1cdfb8..838ca77 100644
--- a/src/uart-test/stm_init.h
+++ b/src/uart-test/stm_init.h
@@ -10,6 +10,7 @@
 #define LED_BLUE	GPIO_PIN_15
 
 extern UART_HandleTypeDef huart1;
+extern UART_HandleTypeDef huart2;
 extern void stm_init(void);