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, 89 insertions, 20 deletions

diff --git a/src/entropy/main.c b/src/entropy/main.c
index e29e00c..f7663f5 100644
--- a/src/entropy/main.c
+++ b/src/entropy/main.c
@@ -42,6 +42,7 @@
 
 extern DMA_HandleTypeDef hdma_tim;
 
+UART_HandleTypeDef *huart;
 __IO ITStatus UartReady = RESET;
 
 static union {
@@ -79,6 +80,7 @@ inline uint32_t get_one_bit(void) __attribute__((__always_inline__));
 volatile uint32_t *restart_DMA(void);
 inline volatile uint32_t *get_DMA_read_buf(void);
 inline uint32_t safe_get_counter(volatile uint32_t *dmabuf, const uint32_t dmabuf_idx);
+void check_uart_rx(UART_HandleTypeDef *this);
 /* static void Error_Handler(void); */
 
 
@@ -86,7 +88,7 @@ inline uint32_t safe_get_counter(volatile uint32_t *dmabuf, const uint32_t dmabu
 int
 main()
 {
-  uint32_t count = 0, send_bytes, idx = 255, send_sync_bytes_in = 0, i;
+  uint32_t count = 0, send_bytes, idx = 255, send_sync_bytes_in = 0, i, timeout;
   uint32_t mode = MODE_ENTROPY;
 
   /* Initialize buffers */
@@ -101,6 +103,8 @@ main()
   restart_DMA();
   restart_DMA();
 
+  huart = &huart1;
+
   /* Toggle GREEN LED to show we've initialized */
   {
     for (i = 0; i < 10; i++) {
@@ -144,7 +148,8 @@ main()
       }
 
     /* Send buf on UART (non blocking interrupt driven send). */
-    if (HAL_UART_Transmit_IT(&huart1, (uint8_t *) buf.rnd + idx, (uint16_t) send_bytes) == HAL_OK) {
+    UartReady = RESET;
+    if (HAL_UART_Transmit_IT(huart, (uint8_t *) buf.rnd + idx, (uint16_t) send_bytes) == HAL_OK) {
 
       if (mode == MODE_ENTROPY) {
 	/* Flip-flop idx between the value 0 and the value BYTES_PER_CHUNK.
@@ -155,15 +160,21 @@ main()
 	get_entropy32(send_bytes / 4, idx / 4);
       }
 
-      while (UartReady != SET) { ; }
-      UartReady = RESET;
-    } else {
-      /* Turn on RED LED for one second */
+      timeout = 0xffff;
+      while (UartReady != SET && timeout) { timeout--; }
+    }
+
+    if (UartReady != SET) {
+      /* Failed to send, turn on RED LED for one second */
       HAL_GPIO_WritePin(LED_PORT, LED_RED, GPIO_PIN_SET);
       HAL_Delay(1000);
       HAL_GPIO_WritePin(LED_PORT, LED_RED, GPIO_PIN_RESET);
     }
 
+    /* Check for UART change request */
+    check_uart_rx(&huart1);
+    check_uart_rx(&huart2);
+
     count++;
   }
 
@@ -347,12 +358,27 @@ inline uint32_t safe_get_counter(volatile uint32_t *dmabuf, const uint32_t dmabu
 /* UART transmit complete callback */
 void HAL_UART_TxCpltCallback(UART_HandleTypeDef *UH)
 {
-  if (UH->Instance == USART1) {
+  if ((UH->Instance == USART1 && huart->Instance == USART1) ||
+      (UH->Instance == USART2 && huart->Instance == USART2)) {
     /* Signal UART transmit complete to the code in the main loop. */
     UartReady = SET;
   }
 }
 
+/*
+ * 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') {
+      huart = this;
+      /* Signal UART transmit complete to the code in the main loop. */
+      UartReady = SET;
+    }
+  }
+}
+
 /**
  * @brief  This function is executed in case of error occurrence.
  * @param  None
diff --git a/src/entropy/stm32f4xx_hal_msp.c b/src/entropy/stm32f4xx_hal_msp.c
index fc27e04..536a78c 100644
--- a/src/entropy/stm32f4xx_hal_msp.c
+++ b/src/entropy/stm32f4xx_hal_msp.c
@@ -58,7 +58,7 @@ void HAL_UART_MspInit(UART_HandleTypeDef* huart)
     */
     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);
@@ -66,6 +66,19 @@ void HAL_UART_MspInit(UART_HandleTypeDef* huart)
     /* 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);
+
+    /* NVIC for interrupt mode */
+    HAL_NVIC_SetPriority(USART2_IRQn, 0, 1);
+    HAL_NVIC_EnableIRQ(USART2_IRQn);
   }
 }
 
@@ -80,6 +93,9 @@ void HAL_UART_MspDeInit(UART_HandleTypeDef* huart)
     PA10    ------> USART1_RX
     */
     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/entropy/stm32f4xx_it.c b/src/entropy/stm32f4xx_it.c
index 231b4fc..d60a229 100644
--- a/src/entropy/stm32f4xx_it.c
+++ b/src/entropy/stm32f4xx_it.c
@@ -41,8 +41,6 @@
 #include "stm32f4xx_it.h"
 #include "stm_init.h"
 
-extern TIM_HandleTypeDef htim2;
-
 /** @addtogroup STM32F4xx_HAL_Examples
   * @{
   */
@@ -171,8 +169,7 @@ 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
+ * @Note   HAL_UART_IRQHandler will call HAL_UART_TxCpltCallback in main.c.
  */
 void USART1_IRQHandler(void)
 {
@@ -180,6 +177,17 @@ void USART1_IRQHandler(void)
 }
 
 /**
+ * @brief  This function handles UART interrupt request.
+ * @param  None
+ * @retval None
+ * @Note   HAL_UART_IRQHandler will call HAL_UART_TxCpltCallback in main.c.
+ */
+void USART2_IRQHandler(void)
+{
+  HAL_UART_IRQHandler(&huart2);
+}
+
+/**
  * @brief  This function handles DMA1 Stream 6 interrupt request.
  * @param  None
  * @retval None
diff --git a/src/entropy/stm_init.c b/src/entropy/stm_init.c
index 4bf35b5..5f69760 100644
--- a/src/entropy/stm_init.c
+++ b/src/entropy/stm_init.c
@@ -38,9 +38,6 @@
 
 /* Includes ------------------------------------------------------------------*/
 #include "stm_init.h"
-//#include "stm32f4xx_hal.h"
-//#include "stm32f4xx_hal_rcc.h"
-
 
 /** @addtogroup STM32F4xx_HAL_Examples
   * @{
@@ -54,6 +51,7 @@
 /* Private define ------------------------------------------------------------*/
 
 #define UART1_BAUD_RATE 460800
+#define UART2_BAUD_RATE 115200
 
 
 /* Private macro -------------------------------------------------------------*/
@@ -62,6 +60,7 @@
 static GPIO_InitTypeDef  GPIO_InitStruct;
 TIM_HandleTypeDef htim2;
 UART_HandleTypeDef huart1;
+UART_HandleTypeDef huart2;
 DMA_HandleTypeDef hdma_tim;
 
 /* Private function prototypes -----------------------------------------------*/
@@ -70,6 +69,7 @@ static void Error_Handler(void);
 static void MX_GPIO_Init(void);
 static void MX_TIM2_Init(uint32_t *counters_buf, uint16_t counters);
 static void MX_USART1_UART_Init(void);
+static void MX_USART2_UART_Init(void);
 /* Private functions ---------------------------------------------------------*/
 
 /**
@@ -103,6 +103,7 @@ void stm_init(uint32_t *buf0, uint16_t counters)
   MX_GPIO_Init();
   MX_TIM2_Init(buf0, counters);
   MX_USART1_UART_Init();
+  MX_USART2_UART_Init();
 }
 
 
@@ -153,7 +154,7 @@ static void SystemClock_Config(void)
   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();
   }
 
@@ -163,7 +164,7 @@ 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();
   }
 
@@ -251,13 +252,12 @@ void MX_TIM2_Init(uint32_t *counters_buf, uint16_t counters)
  */
 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; /* Only Transmit */
+  huart1.Init.Mode         = UART_MODE_TX_RX;
   huart1.Init.HwFlowCtl    = UART_HWCONTROL_NONE;
   huart1.Init.OverSampling = UART_OVERSAMPLING_16;
 
@@ -267,6 +267,24 @@ void MX_USART1_UART_Init(void)
   }
 }
 
+/* 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.
@@ -276,7 +294,7 @@ void MX_USART1_UART_Init(void)
 static void Error_Handler(void)
 {
   HAL_GPIO_WritePin(LED_PORT, LED_RED, GPIO_PIN_SET);
-  while(1) { ;  }
+  while(1) { ; }
 }
 
 #ifdef  USE_FULL_ASSERT
diff --git a/src/entropy/stm_init.h b/src/entropy/stm_init.h
index 6a5de19..d58c254 100644
--- a/src/entropy/stm_init.h
+++ b/src/entropy/stm_init.h
@@ -10,6 +10,7 @@
 #define LED_BLUE	GPIO_PIN_15
 
 extern UART_HandleTypeDef huart1;
+extern UART_HandleTypeDef huart2;
 extern DMA_HandleTypeDef hdma_tim;
 
 extern void stm_init(uint32_t *buf0, uint16_t counters);