单片机DMA驱动串口过程

先上代码：

#define COMM_COM                  USART2
#define COMM_COM_CLK              RCC_APB1Periph_USART2
#define COMM_COM_TX_GPIO_CLK      RCC_AHB1Periph_GPIOD     //UART TX
#define COMM_COM_TX_PIN           GPIO_Pin_5
#define COMM_COM_TX_GPIO_PORT     GPIOD
#define COMM_COM_TX_SOURCE        GPIO_PinSource5
#define COMM_COM_TX_AF            GPIO_AF_USART2
#define COMM_COM_RX_GPIO_CLK      RCC_AHB1Periph_GPIOD     //UART RX
#define COMM_COM_RX_PIN           GPIO_Pin_6
#define COMM_COM_RX_GPIO_PORT     GPIOD
#define COMM_COM_RX_SOURCE        GPIO_PinSource6
#define COMM_COM_RX_AF            GPIO_AF_USART2
#define COMM_COM_IRQn             USART2_IRQn
#define COMM_COM_Priority         9                        //优先级
#define COMM_COM_BaudRate         115200                   //波特率
#define COMM_COM_IRQHandler       USART2_IRQHandler        //中断函数接口(见stm32f4xx_it.c)


USART配置：



/************************************************
函数名称 ：USART_COMM_Configuration
功    能 ：通信串口配置
参    数 ：无
返 回 值 ：无
作    者 ：strongerHuang
*************************************************/
void USART_COMM_Configuration(void)
{
  GPIO_InitTypeDef  GPIO_InitStructure;
  USART_InitTypeDef USART_InitStructure;
  NVIC_InitTypeDef  NVIC_InitStructure;  

  /* 时钟配置 */
  RCC_AHB1PeriphClockCmd(COMM_COM_TX_GPIO_CLK | COMM_COM_RX_GPIO_CLK, ENABLE);  
  if((USART1 == COMM_COM) || (USART6 == COMM_COM))
    RCC_APB2PeriphClockCmd(COMM_COM_CLK, ENABLE);
  else
    RCC_APB1PeriphClockCmd(COMM_COM_CLK, ENABLE);  

  /* 复用配置 */
  GPIO_PinAFConfig(COMM_COM_TX_GPIO_PORT, COMM_COM_TX_SOURCE, COMM_COM_TX_AF);
  GPIO_PinAFConfig(COMM_COM_RX_GPIO_PORT, COMM_COM_RX_SOURCE, COMM_COM_RX_AF);  

  /* 引脚配置 */
  GPIO_InitStructure.GPIO_Pin = COMM_COM_TX_PIN;                     //USART Tx
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;                       //复用模式
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
  GPIO_Init(COMM_COM_TX_GPIO_PORT, &GPIO_InitStructure);

  GPIO_InitStructure.GPIO_Pin = COMM_COM_RX_PIN;                     //USART Rx
  GPIO_Init(COMM_COM_RX_GPIO_PORT, &GPIO_InitStructure);  

  /* NVIC配置 */
  NVIC_InitStructure.NVIC_IRQChannel = COMM_COM_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = COMM_COM_Priority;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);  

  /* USART配置 */
  USART_InitStructure.USART_BaudRate = COMM_COM_BaudRate;            //波特率
  USART_InitStructure.USART_WordLength = USART_WordLength_8b;        //传输位数
  USART_InitStructure.USART_StopBits = USART_StopBits_1;             //停止位
  USART_InitStructure.USART_Parity = USART_Parity_No ;               //校验位
  USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
  USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;    //收发功能
  USART_Init(COMM_COM, &USART_InitStructure);

  USART_ClearFlag(COMM_COM, USART_FLAG_RXNE | USART_FLAG_TC);
  USART_ITConfig(COMM_COM, USART_IT_RXNE, ENABLE);                   //接收中断

  USART_DMACmd(COMM_COM, USART_DMAReq_Tx, ENABLE);                   //使能DMA

  USART_Cmd(COMM_COM, ENABLE);                                       //使能USART
}

DMA配置中的宏定义：

#define COMM_DR_ADDRESS           ((uint32_t)USART2 + 0x04)
#define COMM_DMA                  DMA1
#define COMM_DMA_CLK              RCC_AHB1Periph_DMA1
#define COMM_TX_DMA_CHANNEL       DMA_Channel_4
#define COMM_TX_DMA_STREAM        DMA1_Stream6
#define COMM_TX_DMA_FLAG_TCIF     DMA_FLAG_TCIF6
#define COMM_TX_DMA_IRQn          DMA1_Stream6_IRQn
#define COMM_TX_DMA_Priority      8                        //优先级
#define COMM_TX_DMA_IRQHandler    DMA1_Stream6_IRQHandler  //中断函数接口(见stm32f4xx_it.c)
#define COMM_TX_DMA_IT_TCIF       DMA_IT_TCIF6

通讯串口的配置

/************************************************
函数名称 ：USART_COMM_DMA_Configuration
功    能 ：通信串口的DMA配置
参    数 ：无
返 回 值 ：无
作    者 ：strongerHuang
*************************************************/
void USART_COMM_DMA_Configuration(void)
{
  DMA_InitTypeDef DMA_InitStructure;
  NVIC_InitTypeDef NVIC_InitStructure;  

  /* 使能时钟 */
  RCC_AHB1PeriphClockCmd(COMM_DMA_CLK, ENABLE);  

  /* NVIC配置 */
  NVIC_InitStructure.NVIC_IRQChannel = COMM_TX_DMA_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = COMM_TX_DMA_Priority;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);  

  /* DMA配置 */
  DMA_DeInit(COMM_TX_DMA_STREAM);
  DMA_InitStructure.DMA_Channel = COMM_TX_DMA_CHANNEL;               //DMA通道
  DMA_InitStructure.DMA_PeripheralBaseAddr = COMM_DR_ADDRESS;        //外设地址
  DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)0;               //内存地址(待传入参数)
  DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;            //传输方向
  DMA_InitStructure.DMA_BufferSize = 0;                              //传输长度(待传入参数)
  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;   //外设递增
  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;            //内存递增
  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
  DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;    //数据宽度
  DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;                      //循环模式
  DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;              //优先级
  DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;
  DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
  DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
  DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
  DMA_Init(COMM_TX_DMA_STREAM, &DMA_InitStructure);

  DMA_ClearFlag(COMM_TX_DMA_STREAM, COMM_TX_DMA_FLAG_TCIF);
  DMA_ITConfig(COMM_TX_DMA_STREAM, DMA_IT_TC, ENABLE);               //使能DMA传输完成中断

  DMA_Cmd(COMM_TX_DMA_STREAM, DISABLE);                              //初始化禁止
}

j接下来实现数据发送与接收

/************************************************
函数名称 ：COMM_SendBufByDMA
功    能 ：通信串口通过DMA发送数据
参    数 ：Buf ------ 数据(地址)
            Length --- 数据长度(字节)
返 回 值 ：无
作    者 ：strongerHuang
*************************************************/
void COMM_SendBufByDMA(uint8_t *Buf, uint16_t Length)
{
  DMA_Cmd(COMM_TX_DMA_STREAM, DISABLE);                              //关闭DMA
                                                                     //内存地址
  DMA_MemoryTargetConfig(COMM_TX_DMA_STREAM, (uint32_t)Buf, DMA_Memory_0);
  DMA_SetCurrDataCounter(COMM_TX_DMA_STREAM, Length);                //设置DMA传输长度
  DMA_Cmd(COMM_TX_DMA_STREAM, ENABLE);                               //使能DMA
}

DMA是一种在嵌入式实时任务处理中常用的功能。

而UART发送数据包，使用DMA方式能大量减轻CPU处理的时间，使其CPU资源不被大量浪费，尤其在UART收发大量数据包（如高频率收发指令）时具有明显优势。

　　审核编辑：汤梓红