HAL库的串口DMA接收一旦溢出就会丢数据

本帖最后由 龙吟风独恋云 于 2018-5-11 17:05 编辑

针对第2点，串口DMA接收不能单独停止。

HAL_UART_DMAStop()函数的确是uart接收和发送同时关闭，找了好久终于找到只关闭接收的函数了。
只关闭接收的函数。HAL_UART_AbortReceive()

下面看一下函数具体实现：
HAL_StatusTypeDef HAL_UART_DMAStop(UART_HandleTypeDef *huart)
{
  uint32_t dmarequest = 0x00U;
  /* The Lock is not implemented on this API to allow the user application
     to call the HAL UART API under callbacks HAL_UART_TxCpltCallback() / HAL_UART_RxCpltCallback():
     when calling HAL_DMA_Abort() API the DMA TX/RX Transfer complete interrupt is generated
     and the correspond call back is executed HAL_UART_TxCpltCallback() / HAL_UART_RxCpltCallback()
     */
  /* Stop UART DMA Tx request if ongoing */
  dmarequest = HAL_IS_BIT_SET(huart->Instance->CR3, USART_CR3_DMAT);
  if((huart->gState == HAL_UART_STATE_BUSY_TX) && dmarequest)
  {
    CLEAR_BIT(huart->Instance->CR3, USART_CR3_DMAT);
    /* Abort the UART DMA Tx channel */
    if(huart->hdmatx != NULL)
    {
      HAL_DMA_Abort(huart->hdmatx);
    }
    UART_EndTxTransfer(huart);
  }
  /* Stop UART DMA Rx request if ongoing */
  dmarequest = HAL_IS_BIT_SET(huart->Instance->CR3, USART_CR3_DMAR);
  if((huart->RxState == HAL_UART_STATE_BUSY_RX) && dmarequest)
  {
    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);
  }
  return HAL_OK;
}

主要分为2大部分，处理标志，关闭发送和接收DMA。

HAL_StatusTypeDef HAL_UART_AbortReceive(UART_HandleTypeDef *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);
  /* Disable the UART DMA Rx request if enabled */
  if(HAL_IS_BIT_SET(huart->Instance->CR3, USART_CR3_DMAR))
  {
    CLEAR_BIT(huart->Instance->CR3, USART_CR3_DMAR);
    /* Abort the UART DMA Rx channel : use blocking DMA Abort API (no callback) */
    if(huart->hdmarx != NULL)
    {
      /* Set the UART DMA Abort callback to Null.
         No call back execution at end of DMA abort procedure */
      huart->hdmarx->XferAbortCallback = NULL;
      HAL_DMA_Abort(huart->hdmarx);
    }
  }
  /* Reset Rx transfer counter */
  huart->RxXferCount = 0x00U;
  /* Restore huart->RxState to Ready */
  huart->RxState = HAL_UART_STATE_READY;
  return HAL_OK;
}

也是分为2部分，处理标志和关闭接收DMA。

最简单的实现：
1. 先关闭接收DMA，HAL_DMA_Abort(huart->hdmarx);
2. 置位RX ready状态，huart->RxState = HAL_UART_STATE_READY;
忽略了错误标志和IT标志处理，最保险的方式还是使用HAL_UART_AbortReceive()函数。