STM32L4 ADC partially working

Posted on November 27, 2015 at 17:10

Hello,

I'm using IAR & cubeMX, and the nucleo board

6 regular channels, no injection :

1/ internal TS

2/ A8 (connected to OPAMP 1) forced at 3.3V

3/ A9 forced at 3.3V

4/ A15 (connected to OPAMP 2) forced at 3.3/2 (voltage divider with 2R)

5/ internal vbat

6/ vref

I'm not concerned about speed. I performed a calibration with HAL_ADCEx_Calibration_Start(&hadc1, ADC_SINGLE_ENDED);

Internal channels are working, but external channels are not. The ADC returns something between 400 and 700 (@12bits).

I can change the order of measurments, measure only output channel, measure multiple time the same input, in all case, all order, external channel returns floating values between 400 and 700.

I call the ADC conversion fuction every second with : HAL_ADC_Start_DMA(&hadc1, (uint32_t*)temp, 6);

@main() :

  MX_ADC1_Init();

  hadc1.Instance->CFGR = 0x80000000;

  HAL_ADCEx_Calibration_Start(&hadc1, ADC_SINGLE_ENDED);

@adc.c :

void MX_ADC1_Init(void)

{

  ADC_ChannelConfTypeDef sConfig;

    /**Common config 

    */

  hadc1.Instance = ADC1;

  hadc1.Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV2;

  hadc1.Init.Resolution = ADC_RESOLUTION_12B;

  hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;

  hadc1.Init.ScanConvMode = ADC_SCAN_ENABLE;

  hadc1.Init.EOCSelection = ADC_EOC_SEQ_CONV;

  hadc1.Init.LowPowerAutoWait = ENABLE;

  hadc1.Init.ContinuousConvMode = DISABLE;

  hadc1.Init.NbrOfConversion = 6;

  hadc1.Init.DiscontinuousConvMode = DISABLE;

  hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;

  hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;

  hadc1.Init.DMAContinuousRequests = DISABLE;

  hadc1.Init.Overrun = ADC_OVR_DATA_OVERWRITTEN;

  hadc1.Init.OversamplingMode = DISABLE;

  HAL_ADC_Init(&hadc1);

    /**Configure Regular Channel 

    */

  sConfig.Channel = ADC_CHANNEL_TEMPSENSOR;

  sConfig.Rank = 1;

  sConfig.SamplingTime = ADC_SAMPLETIME_640CYCLES_5;

  sConfig.SingleDiff = ADC_SINGLE_ENDED;

  sConfig.OffsetNumber = ADC_OFFSET_NONE;

  sConfig.Offset = 0;

  HAL_ADC_ConfigChannel(&hadc1, &sConfig);

    /**Configure Regular Channel 

    */

  sConfig.Channel = ADC_CHANNEL_8;

  sConfig.Rank = 2;

  HAL_ADC_ConfigChannel(&hadc1, &sConfig);

    /**Configure Regular Channel 

    */

  sConfig.Channel = ADC_CHANNEL_9;

  sConfig.Rank = 3;

  HAL_ADC_ConfigChannel(&hadc1, &sConfig);

    /**Configure Regular Channel 

    */

  sConfig.Channel = ADC_CHANNEL_15;

  sConfig.Rank = 4;

  HAL_ADC_ConfigChannel(&hadc1, &sConfig);

    /**Configure Regular Channel 

    */

  sConfig.Channel = ADC_CHANNEL_VBAT;

  sConfig.Rank = 5;

  HAL_ADC_ConfigChannel(&hadc1, &sConfig);

    /**Configure Regular Channel 

    */

  sConfig.Channel = ADC_CHANNEL_VREFINT;

  sConfig.Rank = 6;

  HAL_ADC_ConfigChannel(&hadc1, &sConfig);

}