STM32H753 ADC auto calibration not working properly?

[Akash_k]

I am using STM32H753 MCU. I am using ADC1 and ADC2 and calibrated the ADC offset using auto calibration function. But this function is not working properly. I am getting a difference of 50 counts on subsequent starts of my device. I checked this by giving fixed voltage at the input.

I am getting a problem of change in calibration offset (50 counts) every time this function is called during initialization.

/**
  * @brief ADC1 Initialization Function
  * @param None
  * @retval None
  */
void MX_ADC1_Init(void)
{
 
  /* USER CODE BEGIN ADC1_Init 0 */
 
  /* USER CODE END ADC1_Init 0 */
 
  ADC_MultiModeTypeDef multimode = {0};
  ADC_ChannelConfTypeDef sConfig = {0};
 
  /* USER CODE BEGIN ADC1_Init 1 */
 
  /* USER CODE END ADC1_Init 1 */
  /** Common config 
  */
  hadc1.Instance = ADC1;
  hadc1.Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV6;//ADC_CLOCK_ASYNC_DIV4;
  hadc1.Init.Resolution = ADC_RESOLUTION_16B;
  hadc1.Init.ScanConvMode = ADC_SCAN_DISABLE;
  hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
  hadc1.Init.LowPowerAutoWait = DISABLE;
  hadc1.Init.ContinuousConvMode = ENABLE;//
  hadc1.Init.NbrOfConversion = 1;
  hadc1.Init.DiscontinuousConvMode = DISABLE;
  hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
  hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
  hadc1.Init.ConversionDataManagement = ADC_CONVERSIONDATA_DR;
  hadc1.Init.Overrun = ADC_OVR_DATA_OVERWRITTEN;
  hadc1.Init.LeftBitShift = ADC_LEFTBITSHIFT_NONE;
	hadc1.Init.BoostMode = ENABLE;
  hadc1.Init.OversamplingMode = DISABLE;
  if (HAL_ADC_Init(&hadc1) != HAL_OK)
  {
    Error_Handler();
  }
  /** Configure the ADC multi-mode 
  */
  multimode.Mode = ADC_MODE_INDEPENDENT;
  if (HAL_ADCEx_MultiModeConfigChannel(&hadc1, &multimode) != HAL_OK)
  {
    Error_Handler();
  }
  /** Configure Regular Channel 
  */
  sConfig.Channel = ADC_CHANNEL_3;
  sConfig.Rank = ADC_REGULAR_RANK_1;
  sConfig.SamplingTime = ADC_SAMPLETIME_1CYCLE_5;
  sConfig.SingleDiff = ADC_SINGLE_ENDED;
  sConfig.OffsetNumber = ADC_OFFSET_NONE;
  sConfig.Offset = 0;
  if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
  {
    Error_Handler();
  }
	
	
	 if (HAL_ADCEx_Calibration_Start(&hadc1, ADC_CALIB_OFFSET, ADC_SINGLE_ENDED) != HAL_OK)
  {
    Error_Handler();
  }
	
	//HAL_ADC_Start_IT(&hadc1);
  /* USER CODE BEGIN ADC1_Init 2 */
 
  /* USER CODE END ADC1_Init 2 */
//ADC_ConfigureBoostMode(&hadc1);
}
void MX_ADC2_Init(void)
{
 
  /* USER CODE BEGIN ADC1_Init 0 */
 
  /* USER CODE END ADC1_Init 0 */
 
  //ADC_MultiModeTypeDef multimode = {0};
  ADC_ChannelConfTypeDef sConfig = {0};
 
  /* USER CODE BEGIN ADC1_Init 1 */
 
  /* USER CODE END ADC1_Init 1 */
  /** Common config 
  */
  hadc2.Instance = ADC2;
  hadc2.Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV6;//ADC_CLOCK_ASYNC_DIV4;
  hadc2.Init.Resolution = ADC_RESOLUTION_16B;
  hadc2.Init.ScanConvMode = ADC_SCAN_DISABLE;
  hadc2.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
  hadc2.Init.LowPowerAutoWait = DISABLE;
  hadc2.Init.ContinuousConvMode = ENABLE;//
  hadc2.Init.NbrOfConversion = 1;
  hadc2.Init.DiscontinuousConvMode = DISABLE;
  hadc2.Init.ExternalTrigConv = ADC_SOFTWARE_START;
  hadc2.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
  hadc2.Init.ConversionDataManagement = ADC_CONVERSIONDATA_DR;
  hadc2.Init.Overrun = ADC_OVR_DATA_OVERWRITTEN;
  hadc2.Init.LeftBitShift = ADC_LEFTBITSHIFT_NONE;
	hadc2.Init.BoostMode = ENABLE;
  hadc2.Init.OversamplingMode = DISABLE;
  if (HAL_ADC_Init(&hadc2) != HAL_OK)
  {
    Error_Handler();
  }
  /** Configure the ADC multi-mode 
  */
													//  multimode.Mode = ADC_MODE_INDEPENDENT;
													//  if (HAL_ADCEx_MultiModeConfigChannel(&hadc2, &multimode) != HAL_OK)
													//  {
													//    Error_Handler();
													//  }
  /** Configure Regular Channel 
  */
  sConfig.Channel = ADC_CHANNEL_5;//ADC_CHANNEL_4
  sConfig.Rank = ADC_REGULAR_RANK_1;
  sConfig.SamplingTime = ADC_SAMPLETIME_1CYCLE_5;
  sConfig.SingleDiff = ADC_SINGLE_ENDED;
  sConfig.OffsetNumber = ADC_OFFSET_NONE;
  sConfig.Offset = 0;
  if (HAL_ADC_ConfigChannel(&hadc2, &sConfig) != HAL_OK)
  {
    Error_Handler();
  }
	
	
//	 if (HAL_ADCEx_Calibration_Start(&hadc2, ADC_CALIB_OFFSET, ADC_SINGLE_ENDED) != HAL_OK)
//  {
//    Error_Handler();
//  }
	
	//HAL_ADC_Start_IT(&hadc1);
  /* USER CODE BEGIN ADC1_Init 2 */
 
  /* USER CODE END ADC1_Init 2 */
//ADC_ConfigureBoostMode(&hadc2);
}

[Akash_k]

When I am using a fresh new controller ADC is working fine but after many times programming and debugging the controller ADC is showing weird behavior. ADC repeatability is drastically degraded even after giving a highly stable and accurate voltage reference at the ADC input