请教STM32F2XX ADC请教

只看该作者 · 2012-2-20 14:16

本帖最后由 19840312 于 2012-2-20 14:17 编辑

ADC_InitTypeDef    ADC_InitStructure;
ADC_CommonInitTypeDef ADC_CommonInitStructure;
DMA_InitTypeDef    DMA_InitStructure;
GPIO_InitTypeDef    GPIO_InitStructure;

/* Enable ADC3, DMA2 and GPIO clocks ****************************************/
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2 | RCC_AHB1Periph_GPIOF, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC3, ENABLE);

/* DMA2 Stream0 channel2 configuration **************************************/
DMA_InitStructure.DMA_Channel          = DMA_Channel_2;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC3_DR_ADDRESS;
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)ADC3ConvertedValue;
DMA_InitStructure.DMA_DIR             = DMA_DIR_PeripheralToMemory;
DMA_InitStructure.DMA_BufferSize       = ADC_BUFF_LEN ;
DMA_InitStructure.DMA_PeripheralInc    = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc       = DMA_MemoryInc_Enable;//DMA_MemoryInc_Disable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize    = DMA_MemoryDataSize_HalfWord;
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);

/* Configure ADC3 Channel5 Ff7 pin as analog input ******************************/
GPIO_InitStructure.GPIO_Pin  = GPIO_Pin_7 | GPIO_Pin_6;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
GPIO_Init(GPIOF, &GPIO_InitStructure);

/* ADC Common Init **********************************************************/
ADC_CommonInitStructure.ADC_Mode          = ADC_Mode_Independent;
ADC_CommonInitStructure.ADC_Prescaler       = ADC_Prescaler_Div8;
ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;
ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_20Cycles;
ADC_CommonInit(&ADC_CommonInitStructure);

/* ADC3 Init ****************************************************************/
ADC_InitStructure.ADC_Resolution          = ADC_Resolution_12b;
ADC_InitStructure.ADC_ScanConvMode       = ENABLE;//DISABLE;
ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;
ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
ADC_InitStructure.ADC_DataAlign          = ADC_DataAlign_Right;
ADC_InitStructure.ADC_NbrOfConversion    = 2;
ADC_Init(ADC3, &ADC_InitStructure);

/* ADC3 regular channel5 configuration *************************************/
ADC_RegularChannelConfig(ADC3, ADC_Channel_5, 1, ADC_SampleTime_112Cycles);
ADC_RegularChannelConfig(ADC3, ADC_Channel_4, 2, ADC_SampleTime_112Cycles);

  /* Enable DMA request after last transfer (Single-ADC mode) */
ADC_DMARequestAfterLastTransferCmd(ADC3, ENABLE);
/* Enable ADC3 DMA */
ADC_DMACmd(ADC3, ENABLE);
/* Enable ADC3 */
   ADC_Cmd(ADC3, ENABLE);

ADC_SoftwareStartConv(ADC3);

上面为配置：
下面是任务中读取数据
OSTimeDly(500);
   ADC_Cmd(ADC3, DISABLE);
   ADC3_CH5_ConvertedValue = ADC3ConvertedValue[0];
ADC3_CH4_ConvertedValue = ADC3ConvertedValue[1];
   ADC_Cmd(ADC3, ENABLE);
   ADC_SoftwareStartConv(ADC3);

问题：ADC3_CH5_ConvertedValue 和ADC3_CH4_ConvertedValue值不变，在运行不确定时间，有可能是一天后也可能是两天后，也可能是几个小时之后。程序没有死机，运行的时候，“任务中读取数据”函数之前的运行正确，之后也运行正确