STM32 相邻AD通道电压变化影响采样结果

只看该作者 · 2014-8-14 16:02

一、问题描述
   1、配置AIN0~AIN6共7个通道为模拟输入通道，定时器TIM2定时20us周期性触发AD转换（规则转换顺序是AIN0~AIN6顺序转换），AIN0，AIN1，
   AIN2，AIN3连接电位器，这电位器的电压经过一阶滤波后连接到各个模拟输入引脚。现象是：假定AIN1的信号没有变化（电位器没有位置没有变
   化），AIN0的电压信号的变化范围为0V~3.3V，会影响到AIN1的转换结果误差为30mV左右。但是其他通道电压变化不会影响AIN1的转换结果。

  /* DMA1 Channel1 Configuration ----------------------------------------------*/
  DMA_DeInit(DMA1_Channel1);
  DMA_InitStructure.DMA_PeripheralBaseAddr = ADC1_DR_Address;
  DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)ADC_Convert_Result;
  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
  DMA_InitStructure.DMA_BufferSize = 7;                            /* ADC has  seven AIN-Channel--------*/
  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 after transfering 7 AD_convert_data---*/
DMA_ITConfig(DMA1_Channel1,DMA_IT_TC, ENABLE);

/*Clears the DMAy Channel1's interrupt pending bits*/
DMA_ClearITPendingBit(DMA1_IT_TC1);

  /* Enable DMA1 channel1 */
  DMA_Cmd(DMA1_Channel1, ENABLE);

  /* ADC1 configuration ------------------------------------------------------*/
  ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;
  ADC_InitStructure.ADC_ScanConvMode = ENABLE;
  ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;
  ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T1_CC3;
  ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
  ADC_InitStructure.ADC_NbrOfChannel = 7;
  ADC_Init(ADC1, &ADC_InitStructure);

  /* Configures ADC1 regular channel_0 as: first converted channel with a 1.5 cycles sample time */
  ADC_RegularChannelConfig(ADC1, ADC_Channel_0, 1, ADC_SampleTime_13Cycles5);

/* Configures ADC1 regular channel_1 as: first converted channel with a 1.5 cycles sample time */
  ADC_RegularChannelConfig(ADC1, ADC_Channel_1, 2, ADC_SampleTime_13Cycles5);

/* Configures ADC1 regular channel_2 as: first converted channel with a 1.5 cycles sample time */
  ADC_RegularChannelConfig(ADC1, ADC_Channel_2, 3, ADC_SampleTime_13Cycles5);

/* Configures ADC1 regular channel_3 as: first converted channel with a 1.5 cycles sample time */
  ADC_RegularChannelConfig(ADC1, ADC_Channel_3, 4, ADC_SampleTime_13Cycles5);

/* Configures ADC1 regular channel_4 as: first converted channel with a 1.5 cycles sample time */
  ADC_RegularChannelConfig(ADC1, ADC_Channel_4, 5, ADC_SampleTime_13Cycles5);

/* Configures ADC1 regular channel_5 as: first converted channel with a 1.5 cycles sample time */
  ADC_RegularChannelConfig(ADC1, ADC_Channel_5, 6, ADC_SampleTime_13Cycles5);

/* Configures ADC1 regular channel_6 as: first converted channel with a 1.5 cycles sample time */
  ADC_RegularChannelConfig(ADC1, ADC_Channel_6, 7, ADC_SampleTime_13Cycles5);

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

  /* Enable ADC1 external trigger */
  ADC_ExternalTrigConvCmd(ADC1, ENABLE);

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

  /* Enable ADC1 reset calibration register */
  ADC_ResetCalibration(ADC1);

  /* Check the end of ADC1 reset calibration register */
  while(ADC_GetResetCalibrationStatus(ADC1));

  /* Start ADC1 calibration */
  ADC_StartCalibration(ADC1);

  /* Check the end of ADC1 calibration */
  while(ADC_GetCalibrationStatus(ADC1));