STM32F3的ADC使用DMA模式传输转换数据

本文使用ADC转换电位器输出的电压值，并用DMA模式传输转换的结果，每8次采样转换取平均值，做一个简单的数字滤波。

见之前的日记STM32中ADC的使用，只是最后增加一步配置DMA：

DMA for ADC channels features configuration
? To enable the DMA mode for ADC channels group, use the ADC_DMACmd()function.
? To configure the DMA transfer request, use ADC_DMAConfig() function.

(摘自STM32F3官方用户手册UM1581User manual)
1. Enable The DMA controller clock using
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE) function for DMA1 orusing RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA2, ENABLE) function forDMA2.
2. Enable and configure the peripheral to be connected to the DMA channel (except forinternal SRAM / FLASH memories: no initialization is necessary).
3. For a given Channel, program the Source and Destination addresses, the transferDirection, the Buffer Size, the Peripheral and Memory Incrementation mode and Data
Size, the Circular or Normal mode, the channel transfer Priority and the Memory-to-Memory transfer mode (if needed) using the DMA_Init() function.
4. Enable the NVIC and the corresponding interrupt(s) using the function
DMA_ITConfig() if you need to use DMA interrupts.
5. Enable the DMA channel using the DMA_Cmd() function.
6. Activate the needed channel Request using PPP_DMACmd() function for any PPPperipheral except internal SRAM and FLASH (ie. SPI, USART ...) The functionallowing this operation is provided in each PPP peripheral driver (ie. SPI_DMACmd forSPI peripheral).
7. Optionally, you can configure the number of data to be transferred when the channel
is disabled (ie. after each Transfer Complete event or when a Transfer Error occurs)using the function DMA_SetCurrDataCounter(). And you can get the number ofremaining data to be transferred using the function DMA_GetCurrDataCounter() at runtime (when the DMA channel is enabled and running).
8. To control DMA events you can use one of the following two methods:
a. Check on DMA channel flags using the function DMA_GetFlagStatus().
b. Use DMA interrupts through the function DMA_ITConfig() at initialization phaseand DMA_GetITStatus() function into interrupt routines in communication phase.After checking on a flag you should clear it using DMA_ClearFlag() function. Andafter checking on an interrupt event you should clear it usingDMA_ClearITPendingBit()function.

重要代码：

#include"ADC_DMA.h"

#defineDATANUM8

uint8_tFLAG=0;//转换次数标志位

uint16_tCONV_RESULTS[DATANUM];

voidADC_Config(void)

{

ADC_InitTypeDefADC_InitStructure;

ADC_CommonInitTypeDefADC_CommonInitStructure;

RCC_ADCCLKConfig(RCC_ADC12PLLCLK_Div2);

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_ADC12,ENABLE);

//GPIO_Config();//实现采样输入引脚的配置，配置为模拟输入模式

//......其他

ADC_CommonInitStructure.ADC_DMAAccessMode=ADC_DMAAccessMode_2;

ADC_CommonInitStructure.ADC_DMAMode=ADC_DMAMode_Circular;

//.......其他

ADC_CommonInit(USING_ADC,&ADC_CommonInitStructure);

//ADCInit,ADC_Init(USING_ADC,&ADC_InitStructure);

ADC_ITConfig(USING_ADC,ADC_IT_EOC,ENABLE);//开中断

ADC_DMAConfig(USING_ADC,ADC_DMAMode_Circular);//配置ADC_DMA，非常重要

ADC_DMACmd(USING_ADC,ENABLE);//打开ADC_DMA

DMA_Config();

ADC_Cmd(USING_ADC,ENABLE);

while(!ADC_GetFlagStatus(USING_ADC,ADC_FLAG_RDY));

ADC_StartConversion(USING_ADC);

}

voidGPIO_Config(void)

{

//.......

//......

}

voidDMA_Config(void)

{

DMA_InitTypeDefDMA_InitStructure;

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1,ENABLE);

DMA_DeInit(DMA1_Channel1);

DMA_InitStructure.DMA_PeripheralBaseAddr=ADC_DATA_ADDR;//ADC数据寄存器DR的地址

DMA_InitStructure.DMA_MemoryBaseAddr=(u32)&CONV_RESULTS;//存放转换结果的地址

DMA_InitStructure.DMA_DIR=DMA_DIR_PeripheralSRC;

DMA_InitStructure.DMA_BufferSize=DATANUM;

//.....

DMA_Init(DMA1_Channel1,&DMA_InitStructure);

DMA_Cmd(DMA1_Channel1,ENABLE);

}

voidADC1_2_IRQHandler(void)

{

FLAG++;//在主函数中检查FLAG并惊醒处理

//计算转换数据的个数

if(FLAG>DATANUM-1)

{

FLAG=0;

}

ADC_ClearITPendingBit(USING_ADC,ADC_IT_EOC);

}

//获取转换结果的平均值，做滤波处理

uint16_tGetAverage(void)

{

u8i=0;

u16average=0;

u32sum=0,voltage=0;

for(i=0;i

{

sum+=CONV_RESULTS[i];

}

average=sum/DATANUM;

voltage=average*3300/0xFFF;

returnvoltage;

}

//配置中断

voidNVIC_Config(void)

{

NVIC_InitTypeDefNVIC_InitStruct;

NVIC_InitStruct.NVIC_IRQChannel=ADC1_IRQn;

//........

NVIC_Init(&NVIC_InitStruct);

}

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