HAL_SPI_Transmit_IT源码

HAL_SPI_Transmit_IT 函数的源码如下：

HAL_StatusTypeDef HAL_SPI_Transmit_IT(SPI_HandleTypeDef *hspi, uint8_t *pData, uint16_t Size)
{
  /* Check Direction parameter */
  assert_param(IS_SPI_DIRECTION_2LINES_OR_1LINE(hspi->Init.Direction));
  
  /* Process Locked */
  __HAL_LOCK(hspi);
  
  if(hspi->State != HAL_SPI_STATE_READY)
  {
    __HAL_UNLOCK(hspi);
    return HAL_BUSY;
  }
  
  if((pData == NULL ) || (Size == 0)) 
  {
    __HAL_UNLOCK(hspi);
    return  HAL_ERROR;                                    
  }
  
  /* Prepare transfer parameters */
  hspi->pTxBuffPtr = pData;
  hspi->TxXferSize = Size;
  hspi->TxXferCount = Size;
  hspi->TxISR = SPI_TxISR_8BIT;
  
  /* Reset CRC Calculation */
  if(hspi->Init.CRCCalculation == SPI_CRCCALCULATION_ENABLE)
  {
    __HAL_SPI_RESET_CRC(hspi);
  }
  
  /* Set the SPI Tansmit DMA transfer complete callback */
  hspi->hdmatx->XferCpltCallback = SPI_DMAEndOfTx;
  
  /* Set the DMA error callback */
  hspi->hdmatx->XferErrorCallback = SPI_DMAError;
  
  /* Enable the Tx DMA Stream */
  HAL_DMA_Start_IT(hspi->hdmatx, (uint32_t)hspi->pTxBuffPtr, (uint32_t)&hspi->Instance->DR, Size);
  
  /* Enable Tx DMA Request */
  SET_BIT(hspi->Instance->CR2, SPI_CR2_TXDMAEN);
  
  /* Enable the SPI Error Interrupt Bit */
  __HAL_SPI_ENABLE_IT(hspi, (SPI_IT_ERR));
  
  /* Enable Tx DMA Request */
  SET_BIT(hspi->Instance->CR2, SPI_CR2_TXDMAEN);
  
  /* Process Unlocked */
  __HAL_UNLOCK(hspi);
  
  /* Note : The SPI must be enabled after the DMA and interrupts configuration */
  /*        to avoid the risk of SPI interrupt handle execution before DMA */
  /*        interrupt handle */
  
  /* Enable SPI peripheral */
  __HAL_SPI_ENABLE(hspi);
  
  return HAL_OK;
}

这个函数的作用是启动 SPI 的 DMA 发送模式，并且在传输完成后调用回调函数 `SPI_DMAEndOfTx`。函数首先对输入参数进行检查，然后准备传输参数，重置 CRC 计算，设置 DMA 回调和错误回调函数，启动 DMA 传输并启用 SPI 错误中断和 DMA 请求，最后启用 SPI 外设。