STM32F072從零配置工程-基於HAL庫的串口UART_DMA配置

采用HAL庫來實現串口DMA，與單純的串口UART配置不同，串口DMA在MspInit中添加了對DMA的配置；

       配置的過程是從Instance、Direction、PeriphInc/ MemInc、PeriphDataAlignment/ MemDataAlignment、Mode、Priority這幾個方面來配置；

static void MX_USART2_UART_Init(void)
{
  huart2.Instance = USART2;
  huart2.Init.BaudRate = 115200;
  huart2.Init.WordLength = UART_WORDLENGTH_8B;
  huart2.Init.StopBits = UART_STOPBITS_1;
  huart2.Init.Parity = UART_PARITY_NONE;
  huart2.Init.Mode = UART_MODE_TX_RX;
  huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart2.Init.OverSampling = UART_OVERSAMPLING_16;
  huart2.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_UART_Init(&huart2) != HAL_OK)
  {
    Error_Handler();
  }
}

void HAL_UART_MspInit(UART_HandleTypeDef* huart)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
  if(huart->Instance==USART2)
  {
    /* Peripheral clock enable */
    __HAL_RCC_USART2_CLK_ENABLE();
  
    __HAL_RCC_GPIOA_CLK_ENABLE();
    /**USART2 GPIO Configuration    
    PA2     ------> USART2_TX
    PA3     ------> USART2_RX 
    */
    GPIO_InitStruct.Pin = GPIO_PIN_2|GPIO_PIN_3;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_PULLUP;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF1_USART2;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

    /* USART2 DMA Init */
    /* USART2_RX Init */
    hdma_usart2_rx.Instance = DMA1_Channel5;
    hdma_usart2_rx.Init.Direction = DMA_PERIPH_TO_MEMORY;
    hdma_usart2_rx.Init.PeriphInc = DMA_PINC_DISABLE;
    hdma_usart2_rx.Init.MemInc = DMA_MINC_ENABLE;
    hdma_usart2_rx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
    hdma_usart2_rx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
    hdma_usart2_rx.Init.Mode = DMA_NORMAL;
    hdma_usart2_rx.Init.Priority = DMA_PRIORITY_VERY_HIGH;
    if (HAL_DMA_Init(&hdma_usart2_rx) != HAL_OK)
    {
      Error_Handler();
    }

    __HAL_LINKDMA(huart,hdmarx,hdma_usart2_rx);

    /* USART2_TX Init */
    hdma_usart2_tx.Instance = DMA1_Channel4;
    hdma_usart2_tx.Init.Direction = DMA_MEMORY_TO_PERIPH;
    hdma_usart2_tx.Init.PeriphInc = DMA_PINC_DISABLE;
    hdma_usart2_tx.Init.MemInc = DMA_MINC_ENABLE;
    hdma_usart2_tx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
    hdma_usart2_tx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
    hdma_usart2_tx.Init.Mode = DMA_NORMAL;
    hdma_usart2_tx.Init.Priority = DMA_PRIORITY_VERY_HIGH;
    if (HAL_DMA_Init(&hdma_usart2_tx) != HAL_OK)
    {
      Error_Handler();
    }

    __HAL_LINKDMA(huart,hdmatx,hdma_usart2_tx);

    /* USART2 interrupt Init */
    HAL_NVIC_SetPriority(USART2_IRQn, 1, 0);
    HAL_NVIC_EnableIRQ(USART2_IRQn);
  }
}

 

參考主函數main：

#define SENDBUFF_SIZE   100
uint8_t aRxBuffer;
uint8_t aTxBuffer[SENDBUFF_SIZE];
int main(void)
{
  HAL_Init();
  SystemClock_Config();
  MX_GPIO_Init();
  MX_DMA_Init();
  MX_USART2_UART_Init();
  
    for(uint8_t i=0;i<SENDBUFF_SIZE;i++)
    {
        aTxBuffer[i] = 'Y';
    }
  
  HAL_UART_Receive_IT(&huart3,&aRxBuffer,1);
  HAL_UART_Transmit_DMA(&huart3,aTxBuffer, SENDBUFF_SIZE); 
  
  while (1)
  {}
}

 

其中HAL_UART_Receive_IT()的功能還是一樣，開啟相關中斷（PE、EIE、RXNE）；

HAL_UART_Transmit_DMA實現了三個主要的功能：

       使用HAL_DMA_Start_IT配置DMA傳輸的源地址和目標地址、以及傳輸長度；

       使用__HAL_UART_CLEAR_FLAG清除ICR中的TC標志，主要是為了防止第一次接收失敗；

       使用SET_BIT開啟串口的DMA傳輸使能位；

HAL_StatusTypeDef HAL_UART_Receive_IT(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size)
{
  if(huart->RxState == HAL_UART_STATE_READY)
  {
    /* Enable the UART Error Interrupt: (Frame error, noise error, overrun error) */
    SET_BIT(huart->Instance->CR3, USART_CR3_EIE);

    /* Enable the UART Parity Error and Data Register not empty Interrupts */
    SET_BIT(huart->Instance->CR1, USART_CR1_PEIE | USART_CR1_RXNEIE);

    return HAL_OK;
  }
}

HAL_StatusTypeDef HAL_UART_Transmit_DMA(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size)
{
  /* Check that a Tx process is not already ongoing */
  if(huart->gState == HAL_UART_STATE_READY)
  {
    /* Enable the UART transmit DMA channel */
    HAL_DMA_Start_IT(huart->hdmatx, (uint32_t)huart->pTxBuffPtr, (uint32_t)&huart->Instance->TDR, Size);

    /* Clear the TC flag in the ICR register */
    __HAL_UART_CLEAR_FLAG(huart, UART_CLEAR_TCF);

    /* Enable the DMA transfer for transmit request by setting the DMAT bit
       in the UART CR3 register */
    SET_BIT(huart->Instance->CR3, USART_CR3_DMAT);

    return HAL_OK;
  }
}

 

關於串口和DMA中斷的實現：

       其中HAL_UART_IRQHandler函數主要是實現判斷RXNE中斷發生與否，並調用回調函數HAL_UART_RxCpltCallback()來實現具體的函數功能；

/**
  * @brief This function handles USART2 global interrupt / USART2 wake-up interrupt through EXTI line 26.
  */
void USART2_IRQHandler(void)
{
  HAL_UART_IRQHandler(&huart2);
}

/**
  * @brief This function handles DMA1 channel 4, 5, 6 and 7 interrupts.
  */
void DMA1_Channel4_5_6_7_IRQHandler(void)
{
  HAL_DMA_IRQHandler(&hdma_usart2_tx);
  HAL_DMA_IRQHandler(&hdma_usart2_rx);
}

 

其中回調函數的實現同上一章：

       HAL_UART_Transmit實現將數據傳輸出去；

       HAL_UART_Receive_IT實現接收數據的同時開啟相關中斷（PE、EIE和RXNE）；

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
    HAL_UART_Transmit(&huart3, &aRxBuffer, 1, 0);
    HAL_UART_Receive_IT(&huart3, &aRxBuffer, 1);
}

HAL_StatusTypeDef HAL_UART_Transmit(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size, uint32_t Timeout)
{
  if(huart->gState == HAL_UART_STATE_READY)
  {
    huart->TxXferSize = Size;
    huart->TxXferCount = Size;
    while(huart->TxXferCount > 0)
    {
      huart->TxXferCount--;
      if ((huart->Init.WordLength == UART_WORDLENGTH_9B) && (huart->Init.Parity == UART_PARITY_NONE))
      {
        tmp = (uint16_t*) pData;
        huart->Instance->TDR = (*tmp & (uint16_t)0x01FFU);
        pData += 2;
      }
      else
      {
        huart->Instance->TDR = (*pData++ & (uint8_t)0xFFU);
      }
    }
    /* At end of Tx process, restore huart->gState to Ready */
    huart->gState = HAL_UART_STATE_READY;
    
    return HAL_OK;
  }
}

HAL_StatusTypeDef HAL_UART_Receive_IT(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size)
{
  /* Check that a Rx process is not already ongoing */
  if(huart->RxState == HAL_UART_STATE_READY)
  {
    /* Enable the UART Error Interrupt: (Frame error, noise error, overrun error) */
    SET_BIT(huart->Instance->CR3, USART_CR3_EIE);

    /* Enable the UART Parity Error and Data Register not empty Interrupts */
    SET_BIT(huart->Instance->CR1, USART_CR1_PEIE | USART_CR1_RXNEIE);

    return HAL_OK;
  }
}

 

這里看一下DMA中斷中的傳輸函數處理：

       當傳輸完成后，進入DMA中斷函數，判斷相應的DMA通道TC標志位是否置位和DMA的TC使能標志位是否置位；

       接下來清除DMA的TC標志位，同時若定義了回調函數則進入回調函數XferCpltCallback()中；

void HAL_DMA_IRQHandler(DMA_HandleTypeDef *hdma)
{
  /* Transfer Complete Interrupt management ***********************************/
  else if ((RESET != (flag_it & (DMA_FLAG_TC1 << hdma->ChannelIndex))) && (RESET != (source_it & DMA_IT_TC)))
  {
    if((hdma->Instance->CCR & DMA_CCR_CIRC) == 0U)
    {
        /* Disable the transfer complete  & transfer error interrupts */
        /* if the DMA mode is not CIRCULAR */
        hdma->Instance->CCR &= ~(DMA_IT_TC | DMA_IT_TE);
        
        /* Change the DMA state */
        hdma->State = HAL_DMA_STATE_READY;
    }
    
    /* Clear the transfer complete flag */
hdma->DmaBaseAddress->IFCR = DMA_FLAG_TC1 << hdma->ChannelIndex;

    if(hdma->XferCpltCallback != NULL)
    {
        /* Transfer complete callback */
        hdma->XferCpltCallback(hdma);
    }
  }
}