STM32F302差分ADC异常，采集跳动的原因？如何解决？

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA | RCC_AHBPeriph_GPIOC | RCC_AHBPeriph_GPIOF, ENABLE);  

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3
    | GPIO_Pin_4 | GPIO_Pin_5 | GPIO_Pin_6 | GPIO_Pin_7 ;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
  GPIO_Init(GPIOA,  GPIO_InitStructure);

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3 | GPIO_Pin_4;
  GPIO_Init(GPIOC,  GPIO_InitStructure);

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_4;
  GPIO_Init(GPIOF,  GPIO_InitStructure);  
  //ADC Init
  RCC_ADCCLKConfig(RCC_ADC12PLLCLK_Div1);
  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_ADC12, ENABLE);

  ADC_Structinit( ADC_InitStructure);
  /* Calibration procedure */
  ADC_VoltageRegulatorCmd(ADC1, ENABLE);
  ADC_VoltageRegulatorCmd(ADC2, ENABLE);
  vTaskDelay(10);

  ADC_SelectCalibrationMode(ADC1, ADC_CalibrationMode_Differential);
  ADC_StartCalibration(ADC1);
  ADC_SelectCalibrationMode(ADC2, ADC_CalibrationMode_Differential);
  ADC_StartCalibration(ADC2);  

  while(ADC_GetCalibrationStatus(ADC1) != RESET );
  calibration_value1 = ADC_GetCalibrationValue(ADC1);
  while(ADC_GetCalibrationStatus(ADC2) != RESET );
  calibration_value2 = ADC_GetCalibrationValue(ADC2);  

  /* ADC Dual mode configuration */     
  ADC_CommonInitStructure.ADC_Mode = ADC_Mode_RegSimul;                                                                    
  ADC_CommonInitStructure.ADC_Clock = ADC_Clock_AsynClkMode;                    
  ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_1;            
  ADC_CommonInitStructure.ADC_DMAMode = ADC_DMAMode_Circular;                  
  ADC_CommonInitStructure.ADC_TwoSamplingDelay = 10;         

  ADC_CommonInit(ADC1,  ADC_CommonInitStructure);
  /* */  
  ADC_InitStructure.ADC_ContinuousConvMode = ADC_ContinuousConvMode_Disable;//ADC_ContinuousConvMode_Enable;
  ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
  ADC_InitStructure.ADC_ExternalTrigConvEvent = ADC_ExternalTrigConvEvent_5;//Event5 = TIM4_CC4 event          Event12 = TIM4_TROG event
  ADC_InitStructure.ADC_ExternalTrigEventEdge = ADC_ExternalTrigEventEdge_RisingEdge;
  ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
  ADC_InitStructure.ADC_OverrunMode = ADC_OverrunMode_Disable;   
  ADC_InitStructure.ADC_AutoInjMode = ADC_AutoInjec_Disable;  
  ADC_InitStructure.ADC_NbrOfRegChannel = 4;
  ADC_Init(ADC1,  ADC_InitStructure);
  ADC_InitStructure.ADC_ExternalTrigEventEdge = ADC_ExternalTrigEventEdge_None;
  ADC_Init(ADC2,  ADC_InitStructure);  

  /* ADC1 regular channel7 and channel8 configuration */
  ADC_RegularChannelConfig(ADC1, ADC_Channel_1, 1, ADC_SampleTime_61Cycles5);
  ADC_RegularChannelConfig(ADC1, ADC_Channel_2, 2, ADC_SampleTime_61Cycles5);
  ADC_RegularChannelConfig(ADC1, ADC_Channel_3, 3, ADC_SampleTime_61Cycles5);
  ADC_RegularChannelConfig(ADC1, ADC_Channel_4, 4, ADC_SampleTime_61Cycles5);
  ADC_RegularChannelConfig(ADC1, ADC_Channel_5, 5, ADC_SampleTime_61Cycles5);
  ADC_RegularChannelConfig(ADC1, ADC_Channel_6, 6, ADC_SampleTime_61Cycles5);//与ADC2共用CH6,错时使用
  ADC_RegularChannelConfig(ADC1, ADC_Channel_7, 7, ADC_SampleTime_61Cycles5);
  ADC_RegularChannelConfig(ADC1, ADC_Channel_8, 8, ADC_SampleTime_61Cycles5);

  ADC_RegularChannelConfig(ADC2, ADC_Channel_1, 1, ADC_SampleTime_61Cycles5);
  ADC_RegularChannelConfig(ADC2, ADC_Channel_2, 2, ADC_SampleTime_61Cycles5);
  ADC_RegularChannelConfig(ADC2, ADC_Channel_3, 3, ADC_SampleTime_61Cycles5);
  ADC_RegularChannelConfig(ADC2, ADC_Channel_4, 4, ADC_SampleTime_61Cycles5);
  ADC_RegularChannelConfig(ADC2, ADC_Channel_9, 5, ADC_SampleTime_61Cycles5);
  ADC_RegularChannelConfig(ADC2, ADC_Channel_10, 6, ADC_SampleTime_61Cycles5);
  ADC_RegularChannelConfig(ADC2, ADC_Channel_5, 7, ADC_SampleTime_61Cycles5);
  ADC_RegularChannelConfig(ADC2, ADC_Channel_6, 8, ADC_SampleTime_61Cycles5);//与ADC1共用CH6,错时使用

  ADC_SelectDifferentialMode(ADC1, ADC_Channel_1, ENABLE);      //差分通道
  ADC_SelectDifferentialMode(ADC1, ADC_Channel_3, ENABLE);      
  ADC_SelectDifferentialMode(ADC1, ADC_Channel_5, ENABLE);      
  ADC_SelectDifferentialMode(ADC1, ADC_Channel_7, ENABLE);      

  ADC_SelectDifferentialMode(ADC2, ADC_Channel_1, ENABLE);      //差分通道
  ADC_SelectDifferentialMode(ADC2, ADC_Channel_3, ENABLE);      
  ADC_SelectDifferentialMode(ADC2, ADC_Channel_9, ENABLE);      
  ADC_SelectDifferentialMode(ADC2, ADC_Channel_5, ENABLE);   

    /* Configures the ADC DMA */
  ADC_DMAConfig(ADC1, ADC_DMAMode_Circular);
  /* Enable the ADC DMA */
  ADC_DMACmd(ADC1, ENABLE);

  /* Enable ADC1 and ADC2 */
  ADC_Cmd(ADC1, ENABLE);
  ADC_Cmd(ADC2, ENABLE);

    /* wait for ADC1 ADRDY */
  while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_RDY));

  /* wait for ADC2 ADRDY */
  while(!ADC_GetFlagStatus(ADC2, ADC_FLAG_RDY));

  vTaskDelay(10);
  //DMA Init
  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

  DMA_InitStructure.DMA_PeripheralBaseAddr = ADC_CDR_ADDRESS;
  DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t) ADCDualConvertedValue;
  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
  DMA_InitStructure.DMA_BufferSize = 300*4;
  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_Circular;
  DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;
  DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

  DMA_Init(DMA1_Channel1,  DMA_InitStructure);

  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);
  NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel1_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init( NVIC_InitStructure);

  DMA_ITConfig(DMA1_Channel1, DMA_IT_TC, ENABLE);
  DMA_Cmd(DMA1_Channel1, ENABLE);
  //TIM4 Init
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);
  /* TIM4 configuration ------------------------------------------------------*/
  /* Time Base configuration */
  TIM_TimeBaseStructInit( TIM_TimeBaseStructure);
  TIM_TimeBaseStructure.TIM_Period = 24000-1;        //72M/3K = 24K   
  TIM_TimeBaseStructure.TIM_Prescaler = 0;      
  TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;   
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  
  TIM_TimeBaseInit(TIM4,  TIM_TimeBaseStructure);
  /* TIM4 channel1 configuration in PWM mode */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;      
  TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;         
  TIM_OCInitStructure.TIM_Pulse = 0x0FFF;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;  
  TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;
  TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
  TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;      
  TIM_OC4Init(TIM4,  TIM_OCInitStructure);  

  TIM_SelectOutputTrigger(TIM4, TIM_TRGOSource_OC4Ref);
  /* TIM4 counter enable */
  TIM_Cmd(TIM4, ENABLE);

  /* TIM4 main Output Enable */
  TIM_CtrlPWMOutputs(TIM4, ENABLE);
  ADC_StartConversion(ADC1);

采集直流数据，采集变化非常大。采集值有100左右的变化。
另外，如果不添加  ADC_StartConversion(ADC1);，采集是不会开始的，不知道哪里没有配置好。