对于ADC DMA 三重采样

对于DMA的ADC的DMA理论上来说可以达到2.4M SPS ，这是非常的快，对于ST官网的说法是只需要0.41us 的速度就可以采样一次，但是在平常的正常情况下，是达不到2.4M SPS 的，但是可以达到1.2MSPS，假如ADC123同时采样，在ADC1进行采样ADC1值进行转换的时候，ADC2开始进行采样，这样循环下来，就可以理论达到7.2M SPS,这是一个非常恐怖的数字，采样速率可以达到这么快。

#include "adc.h"
#include "delay.h"		 
#include "usart.h"

void ADC_DMA_Config(void)
{                  
  GPIO_InitTypeDef       GPIO_InitStructure;
  DMA_InitTypeDef        DMA_InitStructure;
  ADC_InitTypeDef        ADC_InitStructure;
  ADC_CommonInitTypeDef  ADC_CommonInitStructure;  

  RCC_AHB1PeriphClockCmd( RCC_AHB1Periph_GPIOC , ENABLE);
  RCC_AHB1PeriphClockCmd( RCC_AHB1Periph_DMA2 , ENABLE);
  RCC_APB2PeriphClockCmd( RCC_APB2Periph_ADC1 , ENABLE);
  RCC_APB2PeriphClockCmd( RCC_APB2Periph_ADC2 , ENABLE);
  RCC_APB2PeriphClockCmd( RCC_APB2Periph_ADC3 , ENABLE);  

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
  GPIO_Init(GPIOC, &GPIO_InitStructure);

  DMA_InitStructure.DMA_Channel = DMA_Channel_0;  
  DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)(0x40012308);
  DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&aADCTripleConvertedValue;
  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
  DMA_InitStructure.DMA_BufferSize = 3;
  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Word;
  DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Word;
  DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
  DMA_InitStructure.DMA_Priority = DMA_Priority_High;
  DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;         
  DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
  DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
  DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
  DMA_Init(DMA2_Stream0, &DMA_InitStructure);

  DMA_Cmd(DMA2_Stream0, ENABLE);

  ADC_CommonInitStructure.ADC_Mode = ADC_TripleMode_Interl;
  ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;
  ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_2;  
  ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div2; 
  ADC_CommonInit(&ADC_CommonInitStructure);

  ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
  ADC_InitStructure.ADC_ScanConvMode = DISABLE;
  ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;
  ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
  ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T1_CC1;
  ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
  ADC_InitStructure.ADC_NbrOfConversion = 1;
  ADC_Init(ADC1, &ADC_InitStructure);

  ADC_RegularChannelConfig(ADC1, ADC_Channel_12, 1, ADC_SampleTime_3Cycles);
  ADC_DMACmd(ADC1, ENABLE);

  ADC_Init(ADC2, &ADC_InitStructure);
  ADC_RegularChannelConfig(ADC2, ADC_Channel_12, 1, ADC_SampleTime_3Cycles);

  ADC_Init(ADC3, &ADC_InitStructure); 

  ADC_RegularChannelConfig(ADC3, ADC_Channel_12, 1, ADC_SampleTime_3Cycles);


  ADC_MultiModeDMARequestAfterLastTransferCmd(ENABLE);

  ADC_Cmd(ADC1, ENABLE);

  ADC_Cmd(ADC2, ENABLE);

  ADC_Cmd(ADC3, ENABLE);
	
}

对于这样就可以轻松提高STM32 F407的ADC采样速率。