STM32F103 AD采样结果不正确

2万 · 2019-11-9 11:55

使用STM32F103C8T6进行ADC采样，参考电压3.3V，AD采样口电压1.6V，12位ADC采用右对齐方式，采样结果理论上应该是4096的一半，大概是0x800,可是我采样结果大概是0x00f0，求大神帮忙。

2万 · 2019-11-9 11:59

楼主程序可以公开吗？贴程序看下吧，这么说看不出什么原因

2万 · 2019-11-9 12:02

void GPIO_Configuration(void)
{
      GPIO_InitTypeDef GPIO_InitStructure;

      //===================ADC ===================================
      GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1|GPIO_Pin_2|GPIO_Pin_5|GPIO_Pin_6|GPIO_Pin_7;
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;
      GPIO_Init(GPIOA, &GPIO_InitStructure);

      GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;
      GPIO_Init(GPIOB, &GPIO_InitStructure);
}

void RCC_Configuration(void)
{
      /* Enable GPIO clock */
      RCC_APB2PeriphClockCmd( RCC_APB2Periph_AFIO, ENABLE );
      RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOA, ENABLE );
      RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOB, ENABLE );

      /* TIM2 clock enable */
      RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM2, ENABLE );
      RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1 , ENABLE);
      RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
}

void ADC_Configuration(void)
{
      vu16 i;
      ADC_InitTypeDef ADC_InitStructure;

      ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;
      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 = 6;
      ADC_Init(ADC1, &ADC_InitStructure);
      /* ADC1 regular channel configuration */
      ADC_RegularChannelConfig(ADC1, ADC_Channel_5, 1, ADC_SampleTime_13Cycles5);
      ADC_RegularChannelConfig(ADC1, ADC_Channel_6, 2, ADC_SampleTime_13Cycles5);
      ADC_RegularChannelConfig(ADC1, ADC_Channel_2, 3, ADC_SampleTime_13Cycles5);
      ADC_RegularChannelConfig(ADC1, ADC_Channel_7, 4, ADC_SampleTime_13Cycles5);
      ADC_RegularChannelConfig(ADC1, ADC_Channel_0, 5, ADC_SampleTime_13Cycles5);
      ADC_RegularChannelConfig(ADC1, ADC_Channel_1, 6, ADC_SampleTime_13Cycles5);

      /* Enable ADC1 DMA */
      ADC_DMACmd(ADC1, ENABLE);

      /* Enable ADC1 */
      ADC_Cmd(ADC1, ENABLE);

      /* Enable ADC1 reset calibaration register */
      ADC_ResetCalibration(ADC1);
      /* Check the end of ADC1 reset calibration register */
      i=0;
      while((ADC_GetResetCalibrationStatus(ADC1))&&(i<3000))
      {
            i++;
      }
      /* Start ADC1 calibaration */
      ADC_StartCalibration(ADC1);
      /* Check the end of ADC1 calibration */
      i=0;
      while((ADC_GetCalibrationStatus(ADC1))&&(i<3000))
      {
            i++;
      }
}

void DMA_Configuration(void)
{
      DMA_InitTypeDef DMA_InitStructure;

      /* DMA1 channel1 configuration ----------------------------------------------*/
      DMA_DeInit(DMA1_Channel1);
      DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC1_DR_Address;
      DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)&ADC_ConvertedValue;
      DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
      DMA_InitStructure.DMA_BufferSize =6;
      DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
      DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
      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_M2M = DMA_M2M_Disable;
      DMA_Init(DMA1_Channel1, &DMA_InitStructure);
      /* Enable DMA1 channel1 interrupt*/
      DMA_ITConfig(DMA1_Channel1,DMA_IT_TC,ENABLE);
      /* Enable DMA1 Channel1 */
      DMA_Cmd(DMA1_Channel1, ENABLE);
}

void NVIC_Configuration(void)
{
      NVIC_InitTypeDef NVIC_InitStructure;

      /* Configure the NVIC Preemption Priority Bits */
      NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);

      /* Enable the TIM2 global Interrupt */
      NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
      NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
      NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
      NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
      NVIC_Init(&NVIC_InitStructure);

      NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel1_IRQn; //设置中断通道
      NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority =1;
      NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
      NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
      NVIC_Init(&NVIC_InitStructure);
}

1万 · 2019-11-9 12:04

你的AD值结果处理在哪段啊？

2万 · 2019-11-9 12:06

Timer2 每50US中断一次，触发一次ADC转换，同时读取上一次ADC采样结果

void TIM2_IRQHandler(void)
{
      if (TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET)//溢出中断
      {
            TIM_ClearITPendingBit(TIM2, TIM_FLAG_Update);       //清除TIM2等待中断
            /* Start ADC1 Software Conversion */
            ADC_SoftwareStartConvCmd(ADC1, ENABLE);

            Get_sampling_Peakvalue(&S1_U1_value,NA_channel);
            Get_sampling_Peakvalue(&S1_U2_value,NB_channel);
            Get_sampling_Peakvalue(&S1_U3_value,NC_channel);

            Get_sampling_Peakvalue(&S2_U1_value,RA_channel);
            Get_sampling_Peakvalue(&S2_U2_value,RB_channel);
            Get_sampling_Peakvalue(&S2_U3_value,RC_channel);
      }
}

void DMA1_Channel1_IRQHandler(void)
{
      vu8  i;

      if(DMA1_FLAG_TC1!=RESET)
      {
            DMA_ClearITPendingBit(DMA1_FLAG_TC1);
            for(i=0;i<6;i++)
            {
                     ADC1_ConvertedValueLocal=ADC_ConvertedValue;
            }
      }
}

2万 · 2019-11-9 12:06

ADC采样结果存在数组中暂不处理，先保存最近采样的100个数据，结果大概在0x00f0左右变化

void Get_sampling_Peakvalue(RMS_Value *channel_RMS,Channel_Type channel)
{
      u16 temp;

      switch(channel)
      {
            case NA_channel:
                     channel_RMS->value=ADC1_ConvertedValueLocal[3];
                     break;

            case NB_channel:
                     channel_RMS->value=ADC1_ConvertedValueLocal[4];
                     break;

            case NC_channel:
                     channel_RMS->value=ADC1_ConvertedValueLocal[5];
                     break;

            case RA_channel:
                     channel_RMS->value=ADC1_ConvertedValueLocal[0];
                     break;

            case RB_channel:
                     channel_RMS->value=ADC1_ConvertedValueLocal[1];
                     break;

            case RC_channel:
                     channel_RMS->value=ADC1_ConvertedValueLocal[2];
                     break;
            default:
                     break;
      }
      channel_RMS->value_list[channel_RMS->item]=channel_RMS->value;
      channel_RMS->item++;
      if(channel_RMS->item>99)
      {
            channel_RMS->item=0;
      }
}

2万 · 2019-11-9 12:07

6个通道ADC分别采样两路电源的三相电压，采样结果暂不处理，先保存在数组中

只看该作者 · 2019-11-10 09:20

我用的很正常，会不会是采样周期过短导致，你试下把采样周期放长看看

1万 · 2019-11-10 16:28

你的采样转换周期设的多少？

1万 · 2019-11-10 16:33

50us采6个样采得完吗？

1万 · 2019-11-10 16:37

还有你的 channel_RMS->value类型和你的ADC1_ConvertedValueLocal类型对应吗？

2万 · 2019-11-10 16:40

算了下可以采完，那就是你的返回值类型不对应

2万 · 2019-11-10 16:43

你的adc似乎是使用的1.6v做参考电压，所以，数值才会小，你检查一下电路及设置，参考电压为多少

2万 · 2019-11-10 16:45

现在问题已经很明显了，ADC采样结果高4位被舍弃了，12位ADC采用右对齐方式，比如采样结果是0x07ff, 而我DMA中断读到的值是0x00ff, 如果采样结果是0x0809, 我DMA中断读到的值是0x0009, 我看了一下数据类型设置成16位无符号数，以下是数据类型定义：
vu16  ADC_ConvertedValue[6];
vu16 ADC1_ConvertedValueLocal[6];

DMA中断是这样处理的：
void DMA1_Channel1_IRQHandler(void)
{
      vu8  i;

      if(DMA1_FLAG_TC1!=RESET)
      {
            DMA_ClearITPendingBit(DMA1_FLAG_TC1);
            for(i=0;i<6;i++)
            {
                     ADC1_ConvertedValueLocal[i]=ADC_ConvertedValue[i];
            }
      }
}

不知道为什么DMA方式会自动舍弃采样结果的高4位