STM32标准库中DMA配置详解 （标准库版）

  写博客Mark下自己对STM32中DMA功能的一些分析： 

        先看上图中下左侧的偏移地址，偏移地址是相对于DMA1_BASE的相对地址。查表可得DMA1_BASE的实际物理地址是：0x4002 0000 .故我们可以得出这些寄存器的实际地址是什么。实际上我们对寄存器配置的时候也是对这几个寄存器值进行修改。

DMA_ISR:  0x4002 0000DMA_IFCR  0x4002 0004DMA_CCR1:      0x4002 0008DMA_CNDTR1: 0x4002 000CDMA_CPAR1:    0x4002 0010DMA_CMAR1:   0x4002 0014

接下来，我们去STM32的程序中来分析下DMA配置的详细过程：

我们主要详细的讲解下两个配置函数：DMA_Configuration()和DMA_Init()这两个函数，废话少说，先贴两个函数的代码上来。

void DMA_Configuration(void){DMA_InitTypeDef DMA_InitStructure;/* DMA channel1 configuration */ DMA_DeInit(DMA1_Channel1);//重置DMA的寄存器的值，配置为缺省值DMA_InitStructure.DMA_PeripheralBaseAddr =(u32)&ADC1->DR;/*设置 DMA 外设基地址，即为转换结果的寄存器*/DMA_InitStructure.DMA_MemoryBaseAddr =(u32)&AD_Value;/*定义内存基地址*/DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;/*定义AD外设作为数据传输的来源*/DMA_InitStructure.DMA_BufferSize = N*M;/*指定DMA通道DMA缓存的大小，即需要开辟几个内存空间*/DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;/*寄存器地址国定*/DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;/*设定内存地址递增，即每次DMA都是将*/DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;/* 定义外设和内存的数据宽度*/DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;/*设定DMA工作再循环缓存模式*/DMA_InitStructure.DMA_Priority = DMA_Priority_High;/*设定DMA选定的通道的软件优先级*/DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;//关闭内存到内存的传输   DMA_Init(DMA1_Channel1, &DMA_InitStructure);DMA_Cmd(DMA1_Channel1, ENABLE);/* Enable DMA channel1 */}

void DMA_Init(DMA_Channel_TypeDef* DMAy_Channelx, DMA_InitTypeDef* DMA_InitStruct){  uint32_t tmpreg = 0;/*--------------------------- DMAy Channelx CCR Configuration -----------------*/  /* Get the DMAy_Channelx CCR value */  tmpreg = DMAy_Channelx->CCR;  /* Clear MEM2MEM, PL, MSIZE, PSIZE, MINC, PINC, CIRC and DIR bits */  tmpreg &= CCR_CLEAR_Mask;  /* Configure DMAy Channelx: data transfer, data size, priority level and mode */  /* Set DIR bit according to DMA_DIR value */  /* Set CIRC bit according to DMA_Mode value */  /* Set PINC bit according to DMA_PeripheralInc value */  /* Set MINC bit according to DMA_MemoryInc value */  /* Set PSIZE bits according to DMA_PeripheralDataSize value */  /* Set MSIZE bits according to DMA_MemoryDataSize value */  /* Set PL bits according to DMA_Priority value */  /* Set the MEM2MEM bit according to DMA_M2M value */  tmpreg |= DMA_InitStruct->DMA_DIR | DMA_InitStruct->DMA_Mode |            DMA_InitStruct->DMA_PeripheralInc | DMA_InitStruct->DMA_MemoryInc |            DMA_InitStruct->DMA_PeripheralDataSize | DMA_InitStruct->DMA_MemoryDataSize |            DMA_InitStruct->DMA_Priority | DMA_InitStruct->DMA_M2M;  /* Write to DMAy Channelx CCR */  DMAy_Channelx->CCR = tmpreg;/*--------------------------- DMAy Channelx CNDTR Configuration ---------------*/  /* Write to DMAy Channelx CNDTR */  DMAy_Channelx->CNDTR = DMA_InitStruct->DMA_BufferSize;/*--------------------------- DMAy Channelx CPAR Configuration ----------------*/  /* Write to DMAy Channelx CPAR */  DMAy_Channelx->CPAR = DMA_InitStruct->DMA_PeripheralBaseAddr;/*--------------------------- DMAy Channelx CMAR Configuration ----------------*/  /* Write to DMAy Channelx CMAR */  DMAy_Channelx->CMAR = DMA_InitStruct->DMA_MemoryBaseAddr;}

  将上面两个函数比较一下就可以知道，前者函数对于后者来说就相当于是一个中间量的过程，暂时的将需要的配置参数写入一个结构体DMA_InitTypeDef中，后面调用DMA_Init这个函数之后，重新配置物理地址中DMA的寄存器相应的位。下面附录上两个函数中的结构体参数组成。

typedef struct{  __IO uint32_t CCR;  __IO uint32_t CNDTR;  __IO uint32_t CPAR;  __IO uint32_t CMAR;} DMA_Channel_TypeDef;

DMA_InitTypeDef  DMA_InitStructure;typedef struct{  uint32_t DMA_PeripheralBaseAddr;  uint32_t DMA_MemoryBaseAddr;     uint32_t DMA_DIR;    uint32_t DMA_BufferSize;     uint32_t DMA_PeripheralInc;     uint32_t DMA_MemoryInc;     uint32_t DMA_PeripheralDataSize;   uint32_t DMA_MemoryDataSize;      uint32_t DMA_Mode;      uint32_t DMA_Priority;        uint32_t DMA_M2M;                                                  }DMA_InitTypeDef;