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 0000

DMA_IFCR  0x4002 0004

DMA_CCR1:      0x4002 0008

DMA_CNDTR1: 0x4002 000C

DMA_CPAR1:    0x4002 0010

DMA_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;