STM32接收不定长数据

//Store the revceived bytes number
uint32_t Rev_Size = 0;
//Receive buffer
uint8_t UART_RX_Buf[15];​

• 加入extern uint32_t Rev_Size;变量声明
• 修改HAL_StatusTypeDef HAL_UART_AbortReceive_IT(UART_HandleTypeDef *huart)该函数

  #else
  //修改后的代码
  	CLEAR_BIT(huart->Instance->CR1, (USART_CR1_RXNEIE | USART_CR1_PEIE| USART_CR1_IDLEIE));
  //  CLEAR_BIT(huart->Instance->CR1, (USART_CR1_RXNEIE | USART_CR1_PEIE));//修改前的代码
    CLEAR_BIT(huart->Instance->CR3, USART_CR3_EIE);
  #endif /* USART_CR1_FIFOEN */

• 修改HAL_StatusTypeDef HAL_UART_Receive_DMA(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size)该函数，这里需要注意一下加入代码的位置。

  __HAL_UNLOCK(huart);
  		
  		/* Enable the UART IDLE Interrupt*/   //加入的代码
  		SET_BIT(huart->Instance->CR1, USART_CR1_IDLEIE);
  		
      /* Enable the UART Parity Error Interrupt */
      SET_BIT(huart->Instance->CR1, USART_CR1_PEIE);
  ​

• 修改void HAL_UART_IRQHandler(UART_HandleTypeDef *huart)函数，光放文档里面的是 USART_SR_IDLE需要换成 USART_ISR_IDLE，NDTR换成CNDTR（具体原因看技术手册和源码）

  #if defined(USART_CR1_FIFOEN)
      if (((isrflags & USART_ISR_RXNE_RXFNE) != 0U)
          && (((cr1its & USART_CR1_RXNEIE_RXFNEIE) != 0U)
              || ((cr3its & USART_CR3_RXFTIE) != 0U)))
  #else
  		//加入的代码
  		if(((isrflags & USART_ISR_IDLE) != RESET) && ((cr1its & USART_CR1_IDLEIE) != RESET))
   {
  		//Record the received bytes number
  		Rev_Size = huart->RxXferSize - huart->hdmarx->Instance->CNDTR;
  		//clear the IDLE flag
  		__HAL_UART_CLEAR_IDLEFLAG(huart);
  		//Abord the received process
  		HAL_UART_AbortReceive_IT(huart);
  		return;
   }
  
      if (((isrflags & USART_ISR_RXNE) != 0U)
          && ((cr1its & USART_CR1_RXNEIE) != 0U))
  #endif /* USART_CR1_FIFOEN */
      {
        if (huart->RxISR != NULL)
        {
          huart->RxISR(huart);
        }
        return;
      }
    }​

• 添加中断，该中断是在开启接收后，当接收到的数据没有到达最大的接收位的时候，但是总线上停止了数据传输，总线进入空闲状态，则产生中止中断。，并进入该函数进行数据处理。

  void HAL_UART_AbortReceiveCpltCallback (UART_HandleTypeDef *huart)
  {
   //Print received Bytes
  	printf("\n\r[IDLE]Received %d Bytes:",Rev_Size);
  	for(uint16_t i = 0; i < Rev_Size; i++)
  	{
  	printf(" 0x%02X", UART_RX_Buf[i]);
  	}
  	//Re-start receiving
  	HAL_UART_Receive_DMA(&huart1, UART_RX_Buf, 15);
   /* NOTE : This function should not be modified, when the callback is needed,
   the HAL_UART_AbortTransmitCpltCallback can be implemented in the user 
  file.
   */
  }​

• 该中断的解释

  /**
    * @brief  Abort ongoing Receive transfer (Interrupt mode).
    * @param  huart UART handle.
    * @note   This procedure could be used for aborting any ongoing Rx transfer started in Interrupt or DMA mode.
    * @note   This procedure is executed in Interrupt mode, meaning that abort procedure could be
    *         considered as completed only when user abort complete callback is executed (not when exiting function).
    * @retval HAL status
    */​

• HAL_UART_Receive_DMA(&huart1, UART_RX_Buf, 15)；接收中断的启动函数，通过启动接收，并在中止中断里面再次开启实现循环接收。其中15是最大的可接受的数据。
• 具体使用，需要注意的是，printf函数需要自己加入printf支持。

  int main(void)
  {
    /* USER CODE BEGIN 1 */
  
    /* USER CODE END 1 */
  
    /* MCU Configuration--------------------------------------------------------*/
  
    /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
    HAL_Init();
  
    /* USER CODE BEGIN Init */
  
    /* USER CODE END Init */
  
    /* Configure the system clock */
    SystemClock_Config();
  
    /* USER CODE BEGIN SysInit */
  
    /* USER CODE END SysInit */
  
    /* Initialize all configured peripherals */
    MX_GPIO_Init();
    MX_DMA_Init();
    MX_USART1_UART_Init();
    /* USER CODE BEGIN 2 */
  	printf("123456789\r\n");
  	HAL_UART_Receive_DMA(&huart1, UART_RX_Buf, 15);
    /* USER CODE END 2 */
  
    /* Infinite loop */
    /* USER CODE BEGIN WHILE */
    while (1)
    {
      /* USER CODE END WHILE */
  
      /* USER CODE BEGIN 3 */
    }
    /* USER CODE END 3 */
  }
  ​

• 结果