Stm32 usart+dma usage based on Hal Library

Development board ： Point atom Apollo

Create a project

Can make USART

Turn on DMA

Configuration interrupt

After the above configuration , Click generate project

One 、 receive 、 Send data of specified length

Designated reception 、 The length of the data sent is 1

Define a receive buffer

char tx_buffer[10];

Write interrupt callback function

When receiving interrupt is triggered , Pass the received data through DMA Send out

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {
    
	if (huart->Instance == USART1) {
    
		// Function to use DMA The way of 
		HAL_UART_Transmit_DMA(&huart1,tx_buffer,1);  
	}
}

When the transmission interrupt is triggered , Use DMA Take over

void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart) {
    
	if (huart->Instance == USART1) {
    
		 Function to use DMA The way of 
		HAL_UART_Receive_DMA(&huart1,tx_buffer,1);
	}
}

Enable receive interrupt

stay main.c in

compile 、 Download it to see the effect

Two 、 receive 、 Send variable length data

When receiving variable length , You need to determine USART When is idle , When an idle interrupt is triggered , Prove that all data has been received at this time , need

The functions used are

HAL_UART_DMAStop(UART_HandleTypeDef *huart); // stop it DMA transmission 
__HAL_DMA_GET_COUNTER(__HANDLE__);           // obtain DMA How much data was transmitted 
__HAL_UART_CLEAR_IDLEFLAG(__HANDLE__);       // Clear idle flag 
HAL_UART_Transmit_DMA(UART_HandleTypeDef *huart, const uint8_t *pData, uint16_t Size); // Use DMA By sending 
HAL_UART_Receive_DMA(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size);    // Use DMA To receive 

Enable idle interrupt

stay MX_USART1_UART_Init() Function to add

  /* USER CODE BEGIN USART1_Init 2 */
  // Enable idle interrupt 
  __HAL_UART_ENABLE_IT(&huart1,UART_IT_IDLE);
  /* USER CODE END USART1_Init 2 */

Define a receive buffer

/* USER CODE BEGIN 0 */
#define RXSIZE 1024 /
uint8_t rx_buffer[RXSIZE] = {
    0};
uint16_t RxNum = 0;
/* USER CODE END 0 */

To write USART1 interrupt

/** * @brief This function handles USART1 global interrupt. */
void USART1_IRQHandler(void)
{
    
	/* USER CODE BEGIN USART1_IRQn 0 */
	
	// Determine the idle flag 
	if (__HAL_UART_GET_FLAG(&huart1,UART_FLAG_IDLE) == SET) {
    
		// Clear idle interrupt flag 
		__HAL_UART_CLEAR_IDLEFLAG(&huart1);
		// stop it DMA
		HAL_UART_DMAStop(&huart1);
		// How long data has been received 
		RxNum = RXSIZE - __HAL_DMA_GET_COUNTER(&hdma_usart1_rx);
		// Send the received data out again 
		HAL_UART_Transmit_DMA(&huart1,rx_buffer,RxNum);
	}
	/* USER CODE END USART1_IRQn 0 */
	HAL_UART_IRQHandler(&huart1);
	/* USER CODE BEGIN USART1_IRQn 1 */
	/* USER CODE END USART1_IRQn 1 */
}

Write interrupt callback function

void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart) {
    
  if (huart->Instance == USART1) {
    
    RxNum = 0;
    // Empty a buffer 
    memset(rx_buffer,0,RXSIZE);
    // To enable to receive 
    HAL_UART_Receive_DMA(&huart1,rx_buffer,RXSIZE);
  }
}

Enable receive interrupt

stay main.c in

If you do not add this sentence, you cannot enter the interrupt

compile 、 Download it to see the effect