序言

今天是2021年4月14日，STM32价格超级加倍，这个仇我记下了

HAL库每次串口接收都是固定的，太麻烦，看到一个很好的教程接收任意长度的数据，但是时间有点久远了，搬过来延续一下

修改UART_Receive_IT函数

static HAL_StatusTypeDef UART_Receive_IT(UART_HandleTypeDef *huart)
{
  uint16_t *tmp;

  /* Check that a Rx process is ongoing */
  if (huart->RxState == HAL_UART_STATE_BUSY_RX)
  {
    if (huart->Init.WordLength == UART_WORDLENGTH_9B)
    {
      tmp = (uint16_t *) huart->pRxBuffPtr;
      if (huart->Init.Parity == UART_PARITY_NONE)
      {
        *tmp = (uint16_t)(huart->Instance->DR & (uint16_t)0x01FF);
        huart->pRxBuffPtr += 2U;
      }
      else
      {
        *tmp = (uint16_t)(huart->Instance->DR & (uint16_t)0x00FF);
        huart->pRxBuffPtr += 1U;
      }
    }
    else
    {
      if (huart->Init.Parity == UART_PARITY_NONE) //这部分是奇偶校验
      {
        *huart->pRxBuffPtr++ = (uint8_t)(huart->Instance->DR & (uint8_t)0x00FF);
      }
      else
      {
        *huart->pRxBuffPtr++ = (uint8_t)(huart->Instance->DR & (uint8_t)0x007F);
      }
    }

    if (--huart->RxXferCount == 0U)//判断是否接收完数据，从这里下手
    {
      /* Disable the UART Data Register not empty Interrupt */
      __HAL_UART_DISABLE_IT(huart, UART_IT_RXNE);

      /* Disable the UART Parity Error Interrupt */
      __HAL_UART_DISABLE_IT(huart, UART_IT_PE);

      /* Disable the UART Error Interrupt: (Frame error, noise error, overrun error) */
      __HAL_UART_DISABLE_IT(huart, UART_IT_ERR);

      /* Rx process is completed, restore huart->RxState to Ready */
      huart->RxState = HAL_UART_STATE_READY;

#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)
      /*Call registered Rx complete callback*/
      huart->RxCpltCallback(huart);
#else
      /*Call legacy weak Rx complete callback*/
      HAL_UART_RxCpltCallback(huart);
#endif /* USE_HAL_UART_REGISTER_CALLBACKS */

      return HAL_OK;
    }
    return HAL_OK;
  }
  else
  {
    return HAL_BUSY;
  }
}

这是修改完成的

uint8_t flag=0,Rx_Size=0;
static HAL_StatusTypeDef UART_Receive_IT(UART_HandleTypeDef *huart)
{
  uint8_t  *pdata8bits;
  uint16_t *pdata16bits;

  /* Check that a Rx process is ongoing */
  if (huart->RxState == HAL_UART_STATE_BUSY_RX)
  {
    if ((huart->Init.WordLength == UART_WORDLENGTH_9B) && (huart->Init.Parity == UART_PARITY_NONE))
    {
      pdata8bits  = NULL;
      pdata16bits = (uint16_t *) huart->pRxBuffPtr;
      *pdata16bits = (uint16_t)(huart->Instance->DR & (uint16_t)0x01FF);
      huart->pRxBuffPtr += 2U;
    }
    else
    {
      pdata8bits = (uint8_t *) huart->pRxBuffPtr;
      pdata16bits  = NULL;

      if ((huart->Init.WordLength == UART_WORDLENGTH_9B) || ((huart->Init.WordLength == UART_WORDLENGTH_8B) && (huart->Init.Parity == UART_PARITY_NONE)))
      {
        *pdata8bits = (uint8_t)(huart->Instance->DR & (uint8_t)0x00FF);
	if(((uint8_t)(huart->Instance->DR & (uint8_t)0x00FF))==0x0a) flag++;   //当收到0x0A换行符时认为接收结束。
Rx_Size++;
      }
      else
      {
        *pdata8bits = (uint8_t)(huart->Instance->DR & (uint8_t)0x007F);
      }
      huart->pRxBuffPtr += 1U;
    }

    //if (--huart->RxXferCount == 0U)
    if(flag== 1)
    {
	flag=0;
      /* Disable the UART Data Register not empty Interrupt */
      __HAL_UART_DISABLE_IT(huart, UART_IT_RXNE);

      /* Disable the UART Parity Error Interrupt */
      __HAL_UART_DISABLE_IT(huart, UART_IT_PE);

      /* Disable the UART Error Interrupt: (Frame error, noise error, overrun error) */
      __HAL_UART_DISABLE_IT(huart, UART_IT_ERR);

      /* Rx process is completed, restore huart->RxState to Ready */
      huart->RxState = HAL_UART_STATE_READY;

#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)
      /*Call registered Rx complete callback*/
      huart->RxCpltCallback(huart);
#else
      /*Call legacy weak Rx complete callback*/
      HAL_UART_RxCpltCallback(huart);
#endif /* USE_HAL_UART_REGISTER_CALLBACKS */

      return HAL_OK;
    }
    return HAL_OK;
  }
  else
  {
    return HAL_BUSY;
  }
}

不要忘记上面定义的两个变量”flag”和”Rx_Size”

main.c的更改

在main函数中，引用“Rx_Size”

extern uint8_t Rx_Size;

在串口中断函数中这样写

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
	HAL_UART_Transmit(&huart1 ,(uint8_t *)rx_buf ,Rx_Size ,200);//用串口1打印出来接收的数据，可忽略
    HAL_UART_Receive_IT(&huart1,(uint8_t *)rx_buf, 200);//重新开中断
    for(int i=0;i<Rx_Size;i++)rx_buf[i]=0; //清除接收缓存
    Rx_Size=0;//清除接收的计数，下次接收重新计数
}

完成！现在这样发送多少数据，串口就返回多少数据，但是不要超过定义的数值，比如这里的200