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stm32f4 adc  max sample rate

Question asked by Ermin Arnautovic on Jun 8, 2018
Latest reply on Jun 8, 2018 by Ermin Arnautovic

Hi,

I have a problem to achieve max. sampling rate of 2.4 MSPS(12 Bit) @168 Mhz Clock, AHB2 Bus is running at  84 MHz and ADC Clock = 42 MHz.

 

Any idea why I get just sampling rate of  1.4 MSPS and not maximum sampling rate?

 

 

static void MX_ADC1_Init(void)
{
  ADC_ChannelConfTypeDef sConfig;
    /**Configure the global features of the ADC (Clock, Resolution, Data Alignment and number of conversion)
    */
  hadc1.Instance = ADC1;
  hadc1.Init.ClockPrescaler = ADC_CLOCKPRESCALER_PCLK_DIV2;
  hadc1.Init.Resolution = ADC_RESOLUTION_12B;
  hadc1.Init.ScanConvMode = DISABLE;
  hadc1.Init.ContinuousConvMode = ENABLE;
  hadc1.Init.DiscontinuousConvMode = DISABLE;
  hadc1.Init.NbrOfDiscConversion = 0;
  hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_RISING;
  hadc1.Init.ExternalTrigConv = ADC_EXTERNALTRIGCONV_T3_TRGO;
 // hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
  hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
  hadc1.Init.NbrOfConversion = 1;
  hadc1.Init.DMAContinuousRequests = ENABLE;
  hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
  if (HAL_ADC_Init(&hadc1) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }
    /**Configure for the selected ADC regular channel its corresponding rank in the sequencer and its sample time.
    */
  sConfig.Channel = ADC_CHANNEL_1;
  sConfig.Rank = 1;
  sConfig.SamplingTime = ADC_SAMPLETIME_3CYCLES;
  sConfig.Offset = 0;
  if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }
}

 

 

I would be very thankful…

 

Cheers, 

Ermin

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