本文以STM32F1xx的串口1為例，簡單呈現(xiàn)下使用DMA中斷連續(xù)發(fā)送的代碼

串口DMA配置通?？梢苑譃?個部分：

1.串口配置

2.DMA配置

串口配置

void UART1_Init(u32 bound){

GPIO_InitTypeDef GPIO_InitStructure;

USART_InitTypeDef USART_InitStructure;

NVIC_InitTypeDef NVIC_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1|RCC_APB2Periph_GPIOA|RCC_APB2Periph_AFIO, ENABLE); //使能USART1，GPIOA時鐘

//USART1_TX   GPIOA.9

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9; //PA.9

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //復用推挽輸出

GPIO_Init(GPIOA, &GPIO_InitStructure);//初始化GPIOA.9

NVIC_Init(&NVIC_InitStructure); //根據(jù)指定的參數(shù)初始化VIC寄存器  

  //USART1_RX   GPIOA.10初始化

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;//PA10

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;//浮空輸入

GPIO_Init(GPIOA, &GPIO_InitStructure);//初始化GPIOA.10  

NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=3 ;//搶占優(yōu)先級3

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; //子優(yōu)先級3

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道使能 

//USART 初始化設置

USART_InitStructure.USART_BaudRate = bound;//串口波特率

USART_InitStructure.USART_WordLength = USART_WordLength_8b;//字長為8位數(shù)據(jù)格式

USART_InitStructure.USART_StopBits = USART_StopBits_1;//一個停止位

USART_InitStructure.USART_Parity = USART_Parity_No;//無奇偶校驗位

USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//無硬件數(shù)據(jù)流控制

USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx; //收發(fā)模式

USART_Init(USART1, &USART_InitStructure); //初始化串口1

USART_ITConfig(USART1,USART_IT_IDLE,ENABLE);  //使能空閑中斷

USART_Cmd(USART1, ENABLE);                    //使能串口1 

}

2.DMA配置

本代碼封裝了下DMA配置

void DMA_Config(DMA_Channel_TypeDef*DMA_CHx,u32 cpar,u32 cmar,u32 dma_dir,u32 priority,u16 bufsize)

{

DMA_InitTypeDef DMA_InitStructure;

  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE); //使能DMA傳輸

  DMA_DeInit(DMA_CHx);   //將DMA的通道1寄存器重設為缺省值

DMA_InitStructure.DMA_PeripheralBaseAddr = cpar;  //DMA外設ADC基地址

DMA_InitStructure.DMA_MemoryBaseAddr = cmar;  //DMA內(nèi)存基地址

DMA_InitStructure.DMA_DIR = dma_dir;  //數(shù)據(jù)傳輸方向，從內(nèi)存讀取發(fā)送到外設

DMA_InitStructure.DMA_BufferSize = bufsize;  //DMA通道的DMA緩存的大小

DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;  //外設地址寄存器不變

DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;  //內(nèi)存地址寄存器遞增

DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;  //數(shù)據(jù)寬度為8位

DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte; //數(shù)據(jù)寬度為8位

DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;  //工作在正常緩存模式

DMA_InitStructure.DMA_Priority = priority; //DMA通道 x擁有中優(yōu)先級 

DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;  //DMA通道x沒有設置為內(nèi)存到內(nèi)存?zhèn)鬏?p> DMA_Init(DMA_CHx, &DMA_InitStructure);  

} 

void UART_DMA_Config{

NVIC_InitTypeDef NVIC_InitStructure;

 //配置串口1發(fā)送DMA

DMA_Config(DMA1_Channel4,(u32)&USART1->DR,(u32)USART1_TX_BUF,DMA_DIR_PeripheralDST,DMA_Priority_Medium,0);//DMA1通道4,外設為串口1Tx,存儲器為USART_TX_BUF 

//配置串口1接收DMA

DMA_Config(DMA1_Channel5,(u32)&USART1->DR,(u32)USART1_RX_BUF,DMA_DIR_PeripheralSRC,DMA_Priority_Medium,0);//DMA1通道5,外設為串口1Rx,存儲器為USART_RX_BUF

NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel4_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=0 ;//搶占優(yōu)先級3

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //子優(yōu)先級3

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道使能

NVIC_Init(&NVIC_InitStructure); //根據(jù)指定的參數(shù)初始化VIC寄存器

DMA_ITConfig(DMA1_Channel4,DMA_IT_TC,ENABLE); //開USART1 Tx DMA中斷

USART_DMACmd(USART1,USART_DMAReq_Tx,ENABLE);  //使能串口3的DMA接收

USART_DMACmd(USART1,USART_DMAReq_Rx,ENABLE);  //使能串口3的DMA接收

}

最后是中斷函數(shù)

void USART1_IRQHandler(void)            //串口1中斷服務程序

{

if(USART_GetITStatus(USART1, USART_IT_IDLE) != RESET)  

{  

USART1_RX_CNT = USART1->SR;  

USART1_RX_CNT = USART1->DR; //清USART_IT_IDLE標志

DMA_Cmd(DMA1_Channel5,DISABLE);  

USART_ITConfig(USART1, USART_IT_IDLE, DISABLE); //靜止中斷，防覆蓋

USART1_RX_CNT = USART1_REC_LEN - DMA_GetCurrDataCounter(DMA1_Channel5);  

DMA_SetCurrDataCounter(DMA1_Channel5,USART1_REC_LEN);  

DMA_Cmd(DMA1_Channel5,ENABLE);  

USART_ITConfig(USART1, USART_IT_IDLE, ENABLE); 

}   

}

 //串口1 TX DMA終端

void DMA1_Channel4_IRQHandler(void)   

{

if(DMA_GetITStatus(DMA1_FLAG_TC4))

{

DMA_ClearFlag(DMA1_FLAG_TC4);

if(Txed_Num > Max_Tx_Cnt)

{

Txed_Num = 0;

return;

}

TX_DATA(DATA_Len);

Txed_Num = Txed_Num + 1;

}

}

//DMA發(fā)送代碼

void TX_DATA(u8 len)

{

while(DMA_GetCurrDataCounter(DMA1_Channel4)!=0); //等待通道7傳輸完成   

DMA_Cmd(DMA1_Channel4, DISABLE );  //關閉 指示的通道        

DMA_SetCurrDataCounter(DMA1_Channel4,len);//DMA通道的DMA緩存的大小

DMA_Cmd(DMA1_Channel4, ENABLE);           //開啟DMA傳輸

}

總結

串口DMA發(fā)送中斷配置時，易遺漏

DMA_ITConfig(DMA1_Channel4,DMA_IT_TC,ENABLE);

本例是DMA發(fā)送中斷在 連續(xù)、分次發(fā)送 場景下的應用。