版主看看，是不是stm32的adc有问题

只看该作者 · 2008-7-24 12:44

我用的是stm32fvbt6 72M 我发现ADC有问题，我用的是ADC1和ADC2同时转换，同步规则模式，
ADC0接ADC_Channel_0,ADC_Channel_0通过5.1k电阻连gnd
ADC1接ADC_Channel_,ADC_Channel_通过5.1k电阻连到3.3v
下面是我用不同的采样时间得到的结果
ADC_SampleTime_1Cycles5:ADC0(269-272),ADC1(3530-3532)
ADC_SampleTime_7Cycles5:ADC0(57-63),ADC1(3970-3976)
ADC_SampleTime_13Cycles5:ADC0(10-17),ADC1(4060-4067)
ADC_SampleTime_28Cycles5:ADC0(0-4),ADC1(4090-4095)
ADC_SampleTime_41Cycles5:ADC0(0-1),ADC1(4091-4095)
ADC_SampleTime_55Cycles5:ADC0(0-1),ADC1(4093-4095)
ADC_SampleTime_71Cycles5:ADC0(0-1),ADC1(4092-4095)
ADC_SampleTime_239Cycles5:ADC0(0-3),ADC1(4090-4095)
虽然数据可能有些误差，但是还是可以说明问题，采样时间短时不能得到正确
的结果，我选这个芯片主要是用比较高速ADC，麻烦版主看看。

只看该作者 · 2008-7-24 12:59

      DMA_DeInit(DMA_Channel1);
      DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)ADC1_DR_Address;
      DMA_InitStructure.DMA_MemoryBaseAddr = (u32)DualConvertedValue.ADC_DualConvertedValueTab;
      DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
      DMA_InitStructure.DMA_BufferSize = 1;
      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_Normal;
      DMA_InitStructure.DMA_Priority = DMA_Priority_High;
      DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
      DMA_Init(DMA_Channel1, &DMA_InitStructure);
      /* Enable DMA Channel1 */
      DMA_Cmd(DMA_Channel1, ENABLE);

      /* ADC1 configuration ------------------------------------------------------*/
      ADC_InitStructure.ADC_Mode = ADC_Mode_RegSimult;
      ADC_InitStructure.ADC_ScanConvMode = ENABLE;
      ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;
      ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None;
      ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
      ADC_InitStructure.ADC_NbrOfChannel = 1;
      ADC_Init(ADC1, &ADC_InitStructure);
      /* ADC1 regular channels configuration */
      ADC_RegularChannelConfig(ADC1, ADC_Channel_0, 1, ADC_SampleTime_1Cycles5);
      /* Enable ADC1 DMA */
      ADC_DMACmd(ADC1, ENABLE);
      /* Enable ADC1 external trigger conversion */
      ADC_ExternalTrigConvCmd(ADC1, ENABLE);
       /* Enable ADC1 */
      ADC_Cmd(ADC1, ENABLE);
      /* Enable ADC1 reset calibaration register */
      ADC_ResetCalibration(ADC1);

      /* Check the end of ADC1 reset calibration register */
      while(ADC_GetResetCalibrationStatus(ADC1));
      /* Start ADC1 calibaration */
      ADC_StartCalibration(ADC1);
      /* Check the end of ADC1 calibration */
      while(ADC_GetCalibrationStatus(ADC1));

      /* ADC2 configuration ------------------------------------------------------*/
      ADC_InitStructure.ADC_Mode = ADC_Mode_RegSimult;
      ADC_InitStructure.ADC_ScanConvMode = ENABLE;
      ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;
      ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None;
      ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
      ADC_InitStructure.ADC_NbrOfChannel = 1;
      ADC_Init(ADC2, &ADC_InitStructure);
      /* ADC2 regular channels configuration */
      ADC_RegularChannelConfig(ADC2, ADC_Channel_1, 1, ADC_SampleTime_1Cycles5);

      /* Enable ADC2 DMA */
//      ADC_DMACmd(ADC2, ENABLE);
      /* Enable ADC2 external trigger conversion */
      ADC_ExternalTrigConvCmd(ADC2, ENABLE);
       /* Enable ADC2 */
      ADC_Cmd(ADC2, ENABLE);
      /* Enable ADC2 reset calibaration register */
      ADC_ResetCalibration(ADC2);

      /* Check the end of ADC2 reset calibration register */
      while(ADC_GetResetCalibrationStatus(ADC2));
      /* Start ADC2 calibaration */
      ADC_StartCalibration(ADC2);
      /* Check the end of ADC2 calibration */
      while(ADC_GetCalibrationStatus(ADC2));

只看该作者 · 2008-7-24 13:14

检查AD的时钟设置。RCC内AD的分频系数。
72M的主时钟，对AD分频系数有要求，最少也得4分频。

只看该作者 · 2008-7-24 13:23

RCC_PCLK2_Div4: ADC clock = PCLK2/4
RCC_PCLK2_Div6: ADC clock = PCLK2/6
RCC_PCLK2_Div8: ADC clock = PCLK2/8
我都试了，在RCC_PCLK2_Div8时
ADC_SampleTime_1Cycles5:ADC0(175-181),ADC1(3705-3713)