STM32F4 UART DMA初始化

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F4的片子内部DMA初始化和F103的有很大区别，在这里引入了数据流（Stream），2个DMA共16的数据流（每个控制器8个），每个数据流则可已处理多达8个通道的数据，每个通道都有一个仲裁器处理DMA请求的优先级。下面贴出DMA请求映射事例

在DMA2中可以看出UART1的发送是数据流7的第4通道，接收是数据流5的第4通道。所以在配置DMA时要注意选择对应的数据流然后配置对应的通道，最后初始化对应数据流和对应的通道。

下面贴出代码

	//****************************配置UART1 DMA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 DMA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);