STM32H7串口DMA+空闲中断实现接收和发送不定长度数据

stm32f103芯片的串口一直使用DMA+空闲中断，现在使用stm32h7芯片，打算也使用相同的方法 芯片型号:stm32h743 串口:USART2 代码生成：stm32CubeMX 第一步：使用stm32CubeMX生成代码

第二步：添加自己代码

1.发生空闲中断需要reset DMA重新开始接收数据

HAL_StatusTypeDef HAL_UART_DMAStopRx(UART_HandleTypeDef *huart)
{
          
   
  /* Stop UART DMA Rx request if ongoing */
  if ((huart->RxState == HAL_UART_STATE_BUSY_RX) &&
      (HAL_IS_BIT_SET(huart->Instance->CR3, USART_CR3_DMAR)))
  {
          
   
    CLEAR_BIT(huart->Instance->CR3, USART_CR3_DMAR);

    /* Abort the UART DMA Rx channel */
    if(huart->hdmarx != NULL)
    {
          
   
      HAL_DMA_Abort(huart->hdmarx);
    }

    //UART_EndRxTransfer(huart);
    /* Disable RXNE, PE and ERR (Frame error, noise error, overrun error) interrupts */
	CLEAR_BIT(huart->Instance->CR1, (USART_CR1_RXNEIE | USART_CR1_PEIE));
	CLEAR_BIT(huart->Instance->CR3, USART_CR3_EIE);

	/* At end of Rx process, restore huart->RxState to Ready */
	huart->RxState = HAL_UART_STATE_READY;
  }

  return HAL_OK;
}

串口空闲中断

/**
  * @brief This function handles UART4 global interrupt.
  */
void USART2_IRQHandler(void)
{
          
   
	uint32_t _len_dmarev;
	uint32_t isrflags;
	uint32_t cr1its;
	BaseType_t xHigherPriorityTaskWoken;

	
	HAL_UART_IRQHandler(&UART2_Handler);
  
	isrflags   = READ_REG(UART2_Handler.Instance->ISR);
	cr1its     = READ_REG(UART2_Handler.Instance->CR1);

	if(((isrflags & USART_ISR_IDLE) != RESET) && ((cr1its & USART_CR1_IDLEIE) != RESET))
	{
          
   
		__HAL_UART_CLEAR_IDLEFLAG(&UART2_Handler);

		_len_dmarev = DMA_BUFFER_LENGTH -         				__HAL_DMA_GET_COUNTER(UART2_Handler.hdmarx);

		if(_len_dmarev)
		{
          
   
		  //停止DMA
		  HAL_UART_DMAStopRx(&UART2_Handler);
		//这个地方非常关键，DMA访问的ram，但是CPU访问的是cache，使用下面函数使ram和cache一致
		 SCB_InvalidateDCache_by_Addr((uint32_t *)dma_rx_buf, DMA_BUFFER_LENGTH);
		 
		 xQueueSendToBackFromISR(Keyboard_Queue,(void*)&uart_to_keyboard_msg,&xHigherPriorityTaskWoken);
		 
		 portYIELD_FROM_ISR(xHigherPriorityTaskWoken);

		  HAL_UART_Receive_DMA(&UART2_Handler, dma_rx_buf, DMA_BUFFER_LENGTH);
		  __HAL_UART_DISABLE_IT(&UART2_Handler, UART_IT_ERR);
		  __HAL_UART_DISABLE_IT(&UART2_Handler, UART_IT_PE);
		}
	  else
	  {
          
   
		  READ_REG(UART2_Handler.Instance->RDR);
		  __HAL_UART_CLEAR_OREFLAG(&UART2_Handler);
	  }

  }

}

发送函数

unsigned int KeyboardRs485TxFrame(uint8_t * buffer,uint32_t len) { UINT16 i;

//拷贝数据到DMA buffer
for(i = 0; i < len; i++)
{
	dma_tx_buf[i] = buffer[i]; 
}

//使发送RAM和cache一致
SCB_InvalidateDCache_by_Addr((uint32_t *)dma_tx_buf, DMA_BUFFER_LENGTH);
HAL_UART_Transmit_DMA(&UART2_Handler, dma_tx_buf, len);
return 0;

}

还有一点需要特别注意：DMA访问的是0x24000000以后区域，定义的发送和接收DMA buffer 一定要在这个区域 可使用下面的编译指令： ALIGN_32BYTES(attribute((section (".RAM_D2"))) uint8_t dma_rx_buf[DMA_BUFFER_LENGTH]) ; ALIGN_32BYTES(attribute((section (".RAM_D2"))) uint8_t dma_tx_buf[DMA_BUFFER_LENGTH]);