使用中断方法实现UART不定长数据接收

基础知识

嵌入式开发中，UART串口通信协议是我们常用的通信协议之一，全称叫做通用异步收发传输器（Universal Asynchronous Receiver/Transmitter）。
基本原理：

常见数据结构：

CubeMx配置

硬件平台：STM32F411RE-NUCLEO
UART参数：

这里是用UART2进行数据接受发送
打开UART并设置波特率等：

打开中断：

函数说明

1、HAL_UART_Receive_IT和HAL_UART_Receive的区别就是：中断接收是有数据到了才去读；直接接收是直接读取，如果超时就返回

2、HAL_UART_Receive_IT配置后，有数据来，计数会在调用中断函数之后自动减1。只有到计数为0时，才会关闭中断并调用回调函数。至此有数据来不再调用中断函数，因为中断已经失效。

HAL_UART_Transmit
Function name

HAL_StatusTypeDef HAL_UART_Transmit (UART_HandleTypeDef * huart, uint8_t * pData, uint16_t Size, uint32_t Timeout)

Function description:
Sends an amount of data in blocking mode.

Parameters:
• huart: Pointer to a UART_HandleTypeDef structure that contains the configuration information for the specified UART module.
• pData: Pointer to data buffer (u8 or u16 data elements).
• Size: Amount of data elements (u8 or u16) to be sent
• Timeout: Timeout duration

Return values
• HAL: status

Notes
• When UART parity is not enabled (PCE = 0), and Word Length is configured to 9 bits (M1-M0 = 01), the sent data is handled as a set of u16. In this case, Size must indicate the number of u16 provided through pData.

HAL_UART_Receive
Function name

HAL_StatusTypeDef HAL_UART_Receive (UART_HandleTypeDef * huart, uint8_t * pData, uint16_t Size, uint32_t Timeout)

Function description:
Receives an amount of data in blocking mode.

Parameters
• huart: Pointer to a UART_HandleTypeDef structure that contains the configuration information for the specified UART module.
• pData: Pointer to data buffer (u8 or u16 data elements).
• Size: Amount of data elements (u8 or u16) to be received.
• Timeout: Timeout duration

Return values
• HAL: status

Notes
• When UART parity is not enabled (PCE = 0), and Word Length is configured to 9 bits (M1-M0 = 01), the received data is handled as a set of u16. In this case, Size must indicate the number of u16 available through pData.

HAL_UART_Transmit_IT
Function name

HAL_StatusTypeDef HAL_UART_Transmit_IT (UART_HandleTypeDef * huart, uint8_t * pData, uint16_t Size)

Function description
Sends an amount of data in non blocking mode.

Parameters
• huart: Pointer to a UART_HandleTypeDef structure that contains the configuration information for the specified UART module.
• pData: Pointer to data buffer (u8 or u16 data elements).
• Size: Amount of data elements (u8 or u16) to be sent

Return values
• HAL: status

Notes
• When UART parity is not enabled (PCE = 0), and Word Length is configured to 9 bits (M1-M0 = 01), the sent data is handled as a set of u16. In this case, Size must indicate the number of u16 provided through pData.

HAL_UART_Receive_IT
Function name

HAL_StatusTypeDef HAL_UART_Receive_IT (UART_HandleTypeDef * huart, uint8_t * pData, uint16_t Size)

Function description
Receives an amount of data in non blocking mode.

Parameters
• huart: Pointer to a UART_HandleTypeDef structure that contains the configuration information for the specified UART module.
• pData: Pointer to data buffer (u8 or u16 data elements).
• Size: Amount of data elements (u8 or u16) to be received.

Return values
• HAL: status

Notes
• When UART parity is not enabled (PCE = 0), and Word Length is configured to 9 bits (M1-M0 = 01), the received data is handled as a set of u16. In this case, Size must indicate the number of u16 available through pData.

代码实现

定义一个全局数组用于存放数据

int Rx_pointer = 0;
uint8_t buffer_Rx[100];

main.c中打开中断

uint8_t buffer_Rx[100];

__HAL_UART_ENABLE_IT(&huart2, UART_IT_IDLE);
__HAL_UART_ENABLE_IT(&huart2, UART_IT_RXNE);

stm32f4xx_it.c中修改中断处理函数

/**
  * @brief This function handles USART2 global interrupt.
  */
void USART2_IRQHandler(void)
{
  /* USER CODE BEGIN USART2_IRQn 0 */

  /* USER CODE END USART2_IRQn 0 */
  HAL_UART_IRQHandler(&huart2);
  /* USER CODE BEGIN USART2_IRQn 1 */
  // receive interrupt
  if(__HAL_UART_GET_FLAG(&huart2, UART_FLAG_RXNE))// huart2.Instance->SR & UART_FLAG_RXNE
  {
	  __HAL_UART_CLEAR_FLAG(&huart2, UART_FLAG_RXNE);
	  Rx_pointer ++;
	  buffer_Rx[Rx_pointer] = huart2.Instance->DR;
  }
  //idle interrupt
  if(__HAL_UART_GET_FLAG(&huart2, UART_FLAG_IDLE)) // huart2.Instance->SR & UART_FLAG_IDLE
  {
	  if(Rx_pointer!=0)
	  {
		  Rx_pointer = 0;
		  HAL_UART_Transmit(&huart2, buffer_Rx, sizeof(buffer_Rx), 100);//UART发送函数，将收到的重新发出来
	  }
	  __HAL_UART_CLEAR_FLAG(&huart2, UART_FLAG_IDLE);
	  __HAL_UART_CLEAR_IDLEFLAG(&huart2);//一定要清除IEDLDFLAG 否则会一直卡在中断出不来
  }
  /* USER CODE END USART2_IRQn 1 */
}