STM32F4 UART DMA初始化

F4的片子內部DMA初始化和F103的有很大區別，在這裏引入了數據流（Stream），2個DMA共16的數據流（每個控制器8個），每個數據流則可已處理多達8個通道的數據，每個通道都有一個仲裁器處理DMA請求的優先級。下面貼出DMA請求映射事例

在DMA2中可以看出UART1的發送是數據流7的第4通道，接收是數據流5的第4通道。所以在配置DMA時要注意選擇對應的數據流然後配置對應的通道，最後初始化對應數據流和對應的通道。

下面貼出代碼

	//****************************配置UART1 DMA發送
	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;  //通道選擇
	DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)&USART1->DR;//DMA外設地址
	DMA_InitStructure.DMA_Memory0BaseAddr = (u32)SendBuff;//DMA 存儲器0地址
	DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;//存儲器到外設模式
	DMA_InitStructure.DMA_BufferSize = SEND_BUF_SIZE;//數據傳輸量 
	DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;//外設非增量模式
	DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;//存儲器增量模式
	DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;//外設數據長度:8位
	DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;//存儲器數據長度:8位
	DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;// 使用普通模式 
	DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;//中等優先級
	DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;         
	DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
	DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;//存儲器突發單次傳輸
	DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;//外設突發單次傳輸
	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;  //通道選擇
	DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)&USART1->DR;//DMA外設地址
	DMA_InitStructure.DMA_Memory0BaseAddr = (u32)ReceiveBuff;//DMA 存儲器0地址
	DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory ;//外設到存儲器模式
	DMA_InitStructure.DMA_BufferSize = RECEIVE_BUF_SIZE;//數據傳輸量 
	DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;//外設非增量模式
	DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;//存儲器增量模式
	DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;//外設數據長度:8位
	DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;//存儲器數據長度:8位
	DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;// 使用普通模式 
	DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;//中等優先級
	DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;         
	DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
	DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;//存儲器突發單次傳輸
	DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;//外設突發單次傳輸
	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);  //開啓DMA傳輸 
	
	DMA_ITConfig(DMA2_Stream5,DMA_IT_TC,ENABLE);