ADC with DMA reads random zeros

Hey there,

I'm using a STM32H742 Eval Boards to read analog data with the ADC with DMA. I want to do multiple measuremts very rapidly.

In the first measurment the ADC reads a couple Zeros (see plot, note: plote is bit older and has multiple measurments with Zeros in it. That Problem got solved by altering the SCB_InvalidateDCache_by_Addr function)

My ADC Init:

static void MX_ADC3_Init(void)
{
 
 /* USER CODE BEGIN ADC3_Init 0 */
 
 /* USER CODE END ADC3_Init 0 */
 
 ADC_ChannelConfTypeDef sConfig = {0};
 
 /* USER CODE BEGIN ADC3_Init 1 */
 
 /* USER CODE END ADC3_Init 1 */
 /** Common config 
 */
 hadc3.Instance = ADC3;
 hadc3.Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV8;
 hadc3.Init.Resolution = ADC_RESOLUTION_16B;
 hadc3.Init.ScanConvMode = ADC_SCAN_DISABLE;
 hadc3.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
 hadc3.Init.LowPowerAutoWait = DISABLE;
 hadc3.Init.ContinuousConvMode = ENABLE;
 hadc3.Init.NbrOfConversion = 1;
 hadc3.Init.DiscontinuousConvMode = DISABLE;
 hadc3.Init.ExternalTrigConv = ADC_SOFTWARE_START;
 hadc3.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
 hadc3.Init.ConversionDataManagement = ADC_CONVERSIONDATA_DMA_ONESHOT;
 hadc3.Init.Overrun = ADC_OVR_DATA_PRESERVED;
 hadc3.Init.LeftBitShift = ADC_LEFTBITSHIFT_NONE;
 hadc3.Init.OversamplingMode = DISABLE;
 if (HAL_ADC_Init(&hadc3) != 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_DIFFERENTIAL_ENDED;
 sConfig.OffsetNumber = ADC_OFFSET_NONE;
 sConfig.Offset = 0;
 if (HAL_ADC_ConfigChannel(&hadc3, &sConfig) != HAL_OK)
 {
 Error_Handler();
 }
 /* USER CODE BEGIN ADC3_Init 2 */
 
 /* USER CODE END ADC3_Init 2 */
 
}

The ADC gets called in his function :

void Sweep(void)
{
	iadc_data_callback=0;
 
	HAL_GPIO_WritePin( SWEEP_IN_GPIO_Port, SWEEP_IN_Pin, GPIO_PIN_SET);
 
	if(HAL_ADC_Start_DMA(&hadc3,(uint32_t*) &ADC3_sample_buf[numberofSweeps- 1], ADC_DATA_ARRAY_SIZE))
			Error_Handler();
}

ab the Callback functio looks like this

void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc)
{
 /* Prevent unused argument(s) compilation warning */
 if (hadc == &hadc3)
 {
	HAL_GPIO_WritePin( SWEEP_IN_GPIO_Port, SWEEP_IN_Pin, GPIO_PIN_RESET);
 /* Invalidate complete data cache to get the updated content of the SRAM of the
 * ADC converted data buffer */
 
	SCB_InvalidateDCache_by_Addr((uint32_t *) &ADC3_sample_buf[0],(30*ADC_DATA_ARRAY_SIZE*sizeof(uint16_t)) ); /* size is bytes */
//	SCB_InvalidateDCache_by_Addr((uint32_t *) &ADC3_sample_buf[0],sizeof(ADC3_sample_buf) ); /* size in storage units */
 
 iadc_data_callback |= 0x10;
 
 	numberofSweeps--;
 	if (numberofSweeps)
 	{
 		Sweep();
 
 	}
 	else
 	{
 		CDC_Transmit_HS( (uint8_t*) ADC3_sample_buf, sizeof(ADC3_sample_buf));
 	}
 }
}

I have no Idea where the error comes from.