DMA简介

DMA（Direct Memory Access）直接存储器存取
DMA可以提供外设和存储器或者存储器和存储器之间的高速数据传输，无须CPU干预，节省了CPU的资源
12个独立可配置的通道： DMA1（7个通道）， DMA2（5个通道）每个通道都支持软件触发和特定的硬件触发
STM32F103C8T6 DMA资源：DMA1（7个通道）

存储器映像

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DMA框图

DMA基本结构

自动重装器：转运完成后恢复到初值，决定单次转换还是循环转换
M2M：0位硬件触发（外设到存储器或者存储器到外设），1为软件触发（存储器到存储器）
传输计数器：触发一次，转运一次，计数器减1.
*写传输计数器时，要先关闭DAM使能
DMA请求
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数据宽度与对齐
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数据转运+DMA

#include "DMA.h"
uint16_t SIZE;
void myDMA_Init(uint32_t AddrA,uint32_t AddrB,uint16_t Size)
{
	//开启时钟
	RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1,ENABLE);
	
	SIZE = Size;
	DMA_InitTypeDef DMA_InitStructure;
	DMA_InitStructure.DMA_BufferSize = Size;
	DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;//传输方向
	DMA_InitStructure.DMA_M2M = DMA_M2M_Enable;//触发方式
	DMA_InitStructure.DMA_MemoryBaseAddr = AddrB;//目标地址
	DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;//字节
	DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
	DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;//是否自动重装
	DMA_InitStructure.DMA_PeripheralBaseAddr = AddrA;//源地址
	DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;//字节
	DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Enable;//地址是否递增
	DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;//优先级
	DMA_Init(DMA1_Channel1,&DMA_InitStructure);
	
	
	DMA_Cmd(DMA1_Channel1,DISABLE);
	
}

void myDMA_Transmission(void)
{
	DMA_Cmd(DMA1_Channel1,DISABLE);
	DMA_SetCurrDataCounter(DMA1_Channel1,SIZE);
	DMA_Cmd(DMA1_Channel1,ENABLE);
	
	while(DMA_GetFlagStatus(DMA1_FLAG_TC1) == RESET);
	DMA_ClearFlag(DMA1_FLAG_TC1);
}

ADC扫描模式+DMA
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#include "ADC.h"
uint16_t AD_value[] = {0,0,0,0};

void AD_Init(void)
{
	//开启对应时钟
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1,ENABLE);
	RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1,ENABLE);
	//GPIO初始化
	GPIO_InitTypeDef GPIO_InitStructure;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;//模拟输入
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
	GPIO_InitStructure.GPIO_Speed  =  GPIO_Speed_50MHz;
	
	GPIO_Init(GPIOA,&GPIO_InitStructure);
	
	
	//配置ADC的通道配置
	ADC_RegularChannelConfig(ADC1,ADC_Channel_0,1,ADC_SampleTime_55Cycles5);
	ADC_RegularChannelConfig(ADC1,ADC_Channel_1,2,ADC_SampleTime_55Cycles5);
	ADC_RegularChannelConfig(ADC1,ADC_Channel_2,3,ADC_SampleTime_55Cycles5);
	ADC_RegularChannelConfig(ADC1,ADC_Channel_3,4,ADC_SampleTime_55Cycles5);
	
	ADC_InitTypeDef ADC_InitStructure;
	ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;
	ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;
	ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
	ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None;
	ADC_InitStructure.ADC_NbrOfChannel = 4;
	ADC_InitStructure.ADC_ScanConvMode = ENABLE;
	ADC_Init(ADC1,&ADC_InitStructure);
	
		
	
	DMA_InitTypeDef DMA_InitStructure;
	DMA_InitStructure.DMA_BufferSize = 4;
	DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;//传输方向
	DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;//触发方式
	DMA_InitStructure.DMA_MemoryBaseAddr = (uint16_t)AD_value;//目标地址
	DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;//字节
	DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
	DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;//是否自动重装
	DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&ADC1->DR;//源地址
	DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
	DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;//地址是否递增
	DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;//优先级
	DMA_Init(DMA1_Channel1,&DMA_InitStructure);
	
	DMA_Cmd(DMA1_Channel1,ENABLE);
	ADC_DMACmd(ADC1,ENABLE);
	ADC_Cmd(ADC1,ENABLE);
	
	//ADC校准
	ADC_ResetCalibration(ADC1);//重置所选ADC校准寄存器。
	while(ADC_GetResetCalibrationStatus(ADC1) == SET);//获取所选ADC重置校准寄存器的状态,重置完成硬件清零
	
	ADC_StartCalibration(ADC1);
	while(ADC_GetCalibrationStatus(ADC1) == SET);//获取所选ADC校准状态,校准完成后硬件清零
}


uint16_t AD_GetValue(void)//单通道
{
	DMA_Cmd(DMA1_Channel1,DISABLE);
	DMA_SetCurrDataCounter(DMA1_Channel1,4);
	DMA_Cmd(DMA1_Channel1,ENABLE);
	
	ADC_SoftwareStartConvCmd(ADC1,ENABLE);//ADC软件触发启动转换。
	
	while(DMA_GetFlagStatus(DMA1_FLAG_TC1) == RESET);
	DMA_ClearFlag(DMA1_FLAG_TC1);
}


uint16_t AD_GetAppointValue(uint8_t ADC_Channel)//指定通道
{
	
	ADC_RegularChannelConfig(ADC1,ADC_Channel,1,ADC_SampleTime_55Cycles5);
	ADC_SoftwareStartConvCmd(ADC1,ENABLE);//ADC软件触发启动转换。
	while(ADC_GetFlagStatus(ADC1,ADC_FLAG_EOC) == RESET);
	return ADC_GetConversionValue(ADC1);
}


uint16_t AD_GetVoltage(void)
{
	
	return (AD_GetValue()/4095)*3.3*100;
}