static void ADC_Config(void)

{

  ADC_InitTypeDef     ADC_InitStructure;

  /* ADCs DeInit */

  //ADC_DeInit(ADC1);

  /* Initialize ADC structure */

  ADC_StructInit(&ADC_InitStructure);

  /* Configure the ADC1 in continuous mode with a resolution equal to 12 bits  */

  ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;

  ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;

  ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;

  ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;

  ADC_InitStructure.ADC_ScanDirection = ADC_ScanDirection_Upward;

  ADC_Init(ADC1, &ADC_InitStructure); 

  /* Convert the ADC1 Channel 9 with 239.5 Cycles as sampling time */

  ADC_ChannelConfig(ADC1, ADC_Channel_9 , ADC_SampleTime_239_5Cycles);

  /* ADC Calibration */

  ADC_GetCalibrationFactor(ADC1);

  /* ADC DMA request in circular mode */

  //ADC_DMARequestModeConfig(ADC1, ADC_DMAMode_Circular);

  /* Enable ADC_DMA */

  //ADC_DMACmd(ADC1, ENABLE);  

  /* Enable the ADC peripheral */

  ADC_Cmd(ADC1, ENABLE);     

  /* Wait the ADRDY flag */

  while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_ADRDY)); 

  /* ADC1 regular Software Start Conv */

  ADC_StartOfConversion(ADC1);

}

 while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC ));//等待转换结束

      _adc=ADC_GetConversionValue(ADC1);