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 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;