STM32F4 UART1 DMA发送和接收不定长度数据

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/louyangyang91/article/details/51504177

STM32F4 串口收发使用DMA还是很方便的。但是配置DMA时需要配置数据长度，这一点对于发送来说可以预估计自己发送的长度来配置DMA发送数据长度，但是对于接收不是很好解决，因为如果使用DMA接收中断是要配置的数据长度减到0才能出发中断。但是我们无法判断接受数据的长度，导致无法判断数据接收完成。网上有提出的解决方法是用定时器固定周期的读DMA接收的长度来判断是否接收完成，也有使用UART的空闲中断来处理的。在这里我使用UART的空闲中断来处理接收不定长数据。当然也要打开DMA接收完成中断，处理数据接收超过DMA配置的长度导致的DMA接收中断。

1.使用DMA发送时每次发送数据前需要配置发送的数据长度，此时要注意应先关闭DMA，然后配置数据长度，最后开启DMA发送，同时在DMA发送中断里面不要忘记清除相应的中断标志位。

2.DMA接收长度达到配置长度后会导致接收中断，此时在中断处理函数内要先关闭DMA，然后读出数据长度，清掉相应的中断标志位，最后重新配置DMA接收长度并打开DMA接收。在这里的DMA中断指示为了防护一次性接收数据超过DMA配置长度。

3.UART空闲中断，利用空闲中断可以很好地判断DMA接收不定长度的数据是否完成。初始化UART时打开空闲中断。当数据接收完成后会触发UART空闲中断。在中断内首先关闭DMA，读出DMA接收到的数据长度，清除DMA标志，重新配置DMA接收长度，清除空闲中断标志IDLE。这里要注意清除IDLE要由软件序列清除即依次读取USART1->SR;和USART1->DR;

下面贴出代码方便以后查看

u8  ReceiveBuff[RECEIVE_BUF_SIZE];   //接收缓冲
u8  SendBuff[SEND_BUF_SIZE];	//发送数据缓冲区

u16 UART1_ReceiveSize = 0;

//初始化IO 串口1 
//bound:波特率
void uart_init(u32 bound)
{
	//GPIO端口设置
	GPIO_InitTypeDef GPIO_InitStructure;
	USART_InitTypeDef USART_InitStructure;
	NVIC_InitTypeDef NVIC_InitStructure;
	DMA_InitTypeDef  DMA_InitStructure;

	RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA,ENABLE); //使能GPIOA时钟
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1,ENABLE);//使能USART1时钟
	RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2,ENABLE);//DMA2时钟使能 

	//串口1对应引脚复用映射
	GPIO_PinAFConfig(GPIOA,GPIO_PinSource9,GPIO_AF_USART1); //GPIOA9复用为USART1
	GPIO_PinAFConfig(GPIOA,GPIO_PinSource10,GPIO_AF_USART1); //GPIOA10复用为USART1

	//USART1端口配置
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_10; //GPIOA9与GPIOA10
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;//复用功能
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;	//速度50MHz
	GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; //推挽复用输出
	GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP; //上拉
	GPIO_Init(GPIOA,&GPIO_InitStructure); //初始化PA9，PA10

	//USART1 初始化设置
	USART_InitStructure.USART_BaudRate = bound;//波特率设置
	USART_InitStructure.USART_WordLength = USART_WordLength_8b;//字长为8位数据格式
	USART_InitStructure.USART_StopBits = USART_StopBits_1;//一个停止位
	USART_InitStructure.USART_Parity = USART_Parity_No;//无奇偶校验位
	USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//无硬件数据流控制
	USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;	//收发模式
	USART_Init(USART1, &USART_InitStructure); //初始化串口1

	USART_Cmd(USART1, ENABLE);  //使能串口1 

	//USART_ClearFlag(USART1, USART_FLAG_TC);
	
	USART_ITConfig(USART1, USART_IT_IDLE, ENABLE);//开启相关中断

	//Usart1 NVIC 配置
	NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;//串口1中断通道
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=3;//抢占优先级3
	NVIC_InitStructure.NVIC_IRQChannelSubPriority =3;		//子优先级3
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;			//IRQ通道使能
	NVIC_Init(&NVIC_InitStructure);	//根据指定的参数初始化VIC寄存器、

	USART_DMACmd(USART1,USART_DMAReq_Tx,ENABLE);  //使能串口1的DMA发送   
	USART_DMACmd(USART1,USART_DMAReq_Rx,ENABLE);  //使能串口1的DMA接收


	//****************************配置UART1发送
	DMA_DeInit(DMA2_Stream7);
	while (DMA_GetCmdStatus(DMA2_Stream7) != DISABLE);//等待DMA可配置 
	/* 配置 DMA Stream */
	DMA_InitStructure.DMA_Channel = DMA_Channel_4;  //通道选择
	DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)&USART1->DR;//DMA外设地址
	DMA_InitStructure.DMA_Memory0BaseAddr = (u32)SendBuff;//DMA 存储器0地址
	DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;//存储器到外设模式
	DMA_InitStructure.DMA_BufferSize = SEND_BUF_SIZE;//数据传输量 
	DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;//外设非增量模式
	DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;//存储器增量模式
	DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;//外设数据长度:8位
	DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;//存储器数据长度:8位
	DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;// 使用普通模式 
	DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;//中等优先级
	DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;         
	DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
	DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;//存储器突发单次传输
	DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;//外设突发单次传输
	DMA_Init(DMA2_Stream7, &DMA_InitStructure);//初始化DMA Stream
	//DMA NVIC  
	NVIC_InitStructure.NVIC_IRQChannel = DMA2_Stream7_IRQn;  
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;  
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;  
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;  
	NVIC_Init(&NVIC_InitStructure);  
	DMA_ITConfig(DMA2_Stream7,DMA_IT_TC,ENABLE);

	//****************************配置UART1接收
	DMA_DeInit(DMA2_Stream5);
	while (DMA_GetCmdStatus(DMA2_Stream5) != DISABLE);//等待DMA可配置 
	/* 配置 DMA Stream */
	DMA_InitStructure.DMA_Channel = DMA_Channel_4;  //通道选择
	DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)&USART1->DR;//DMA外设地址
	DMA_InitStructure.DMA_Memory0BaseAddr = (u32)ReceiveBuff;//DMA 存储器0地址
	DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory ;//外设到存储器模式
	DMA_InitStructure.DMA_BufferSize = RECEIVE_BUF_SIZE;//数据传输量 
	DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;//外设非增量模式
	DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;//存储器增量模式
	DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;//外设数据长度:8位
	DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;//存储器数据长度:8位
	DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;// 使用普通模式 
	DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;//中等优先级
	DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;         
	DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
	DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;//存储器突发单次传输
	DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;//外设突发单次传输
	DMA_Init(DMA2_Stream5, &DMA_InitStructure);//初始化DMA Stream
	//DMA NVIC  
	NVIC_InitStructure.NVIC_IRQChannel = DMA2_Stream5_IRQn;  
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;  
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;  
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;  
	NVIC_Init(&NVIC_InitStructure);  
	DMA_Cmd(DMA2_Stream5, ENABLE);  //开启DMA传输 
	
	DMA_ITConfig(DMA2_Stream5,DMA_IT_TC,ENABLE);
	
}

//开启一次DMA传输
//DMA_Streamx:DMA数据流,DMA1_Stream0~7/DMA2_Stream0~7 
//ndtr:数据传输量  
void DmaSendDataProc(DMA_Stream_TypeDef *DMA_Streamx,u16 ndtr)
{
 
	DMA_Cmd(DMA_Streamx, DISABLE);                      //关闭DMA传输 
	
	while (DMA_GetCmdStatus(DMA_Streamx) != DISABLE){}	//确保DMA可以被设置  
		
	DMA_SetCurrDataCounter(DMA_Streamx,ndtr);          //数据传输量  
 
	DMA_Cmd(DMA_Streamx, ENABLE);                      //开启DMA传输 
}	  

///////////////////////////////////////////////////////////////////////////
//串口1
//发送单字节
 void SendByteInfoProc(u8 nSendInfo)
{
	u8 *pBuf = NULL;
	//指向发送缓冲区
	pBuf = SendBuff;
	*pBuf++ = nSendInfo;

	DmaSendDataProc(DMA2_Stream7,1); //开始一次DMA传输！	  
}
//发送多字节
void SendBytesInfoProc(u8* pSendInfo, u16 nSendCount)
{
	u16 i = 0;
	u8 *pBuf = NULL;
	//指向发送缓冲区
	pBuf = SendBuff;

	for (i=0; i<nSendCount; i++)
	{
		*pBuf++ = pSendInfo[i];
	}
	//DMA发送方式
	DmaSendDataProc(DMA2_Stream7,nSendCount); //开始一次DMA传输！	  
}

//发送完成中断
void DMA2_Stream7_IRQHandler(void)
{
	//清除标志
	if(DMA_GetFlagStatus(DMA2_Stream7,DMA_FLAG_TCIF7)!=RESET)//等待DMA2_Steam7传输完成
	{ 
		DMA_ClearFlag(DMA2_Stream7,DMA_FLAG_TCIF7);//清除DMA2_Steam7传输完成标志
	}
}
//接收完成中断
void DMA2_Stream5_IRQHandler(void)
{
	//清除标志
	if(DMA_GetFlagStatus(DMA2_Stream5,DMA_FLAG_TCIF5)!=RESET)//等待DMA2_Steam7传输完成
	{ 
		DMA_Cmd(DMA2_Stream5, DISABLE); //关闭DMA,防止处理其间有数据

		UART1_ReceiveSize =RECEIVE_BUF_SIZE - DMA_GetCurrDataCounter(DMA2_Stream5);
		if(UART1_ReceiveSize !=0)
		{
			OSSemPost(DMAReceiveSize_Sem);
		}
		
		DMA_ClearFlag(DMA2_Stream5,DMA_FLAG_TCIF5 | DMA_FLAG_FEIF5 | DMA_FLAG_DMEIF5 | DMA_FLAG_TEIF5 | DMA_FLAG_HTIF5);//清除DMA2_Steam7传输完成标志
		DMA_SetCurrDataCounter(DMA2_Stream5, RECEIVE_BUF_SIZE);
		DMA_Cmd(DMA2_Stream5, ENABLE);     //打开DMA,
	}
}

//空闲中断
void USART1_IRQHandler(void)
{
	u16 data;
	if(USART_GetITStatus(USART1,USART_IT_IDLE) != RESET)
	{
		DMA_Cmd(DMA2_Stream5, DISABLE); //关闭DMA,防止处理其间有数据

		data = USART1->SR;
		data = USART1->DR;
		
		UART1_ReceiveSize =RECEIVE_BUF_SIZE - DMA_GetCurrDataCounter(DMA2_Stream5);
		if(UART1_ReceiveSize !=0)
		{
			OSSemPost(DMAReceiveSize_Sem);
		}
		DMA_ClearFlag(DMA2_Stream5,DMA_FLAG_TCIF5 | DMA_FLAG_FEIF5 | DMA_FLAG_DMEIF5 | DMA_FLAG_TEIF5 | DMA_FLAG_HTIF5);//清除DMA2_Steam7传输完成标志
		DMA_SetCurrDataCounter(DMA2_Stream5, RECEIVE_BUF_SIZE);
		DMA_Cmd(DMA2_Stream5, ENABLE);     //打开DMA,

	}
} 

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