Help me understand how to fix this issues with ADC scan feature

Hello,

I'm using a STM32G431 MCU ADCs in dual mode. I'm trying to get control of the sampling rate and have found a frustrating issue. I don't need to scan multiple channels. Though the only way to get maximum sampling rate, or to have any control over the sampling rate via prescaler, is to enable scan mode. That would be an acceptable work around, but scan mode introduces its own unwanted artifacts into the samples. In scan mode, though I can get the rate I want, I have the extra data from the scanned channels which I do not need.

If I don't use scan mode, the sampling rate is fixed somewhere around 300ksps which is not fast enough. Besides that, slowing the sampling rate is apparently not possible via prescaler in this case.

Any ideas how I can do these conversions, without scan mode, while having full control of the adc clock?

void
MX_ADC1_Init
(
void
)
{
 
 
 
 ADC_MultiModeTypeDef multimode = {0};
 ADC_ChannelConfTypeDef sConfig = {0};
 
 hadc1.Instance = ADC1;
 
 hadc1.Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV2;
 hadc1.Init.Resolution = ADC_RESOLUTION_12B;
 hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
 hadc1.Init.GainCompensation = 0;
 hadc1.Init.ScanConvMode = ADC_SCAN_ENABLE;
 hadc1.Init.EOCSelection =ADC_EOC_SINGLE_CONV;
 hadc1.Init.LowPowerAutoWait = DISABLE;
 hadc1.Init.ContinuousConvMode = DISABLE;
 hadc1.Init.NbrOfConversion = 5;//ADC_BUFFER_LEN;
 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_PRESERVED;
 hadc1.Init.OversamplingMode = DISABLE;
 
/* oversmp.Ratio=ADC_OVERSAMPLING_RATIO_16;
 oversmp.RightBitShift =0;
 oversmp.TriggeredMode = ADC_TRIGGEREDMODE_SINGLE_TRIGGER;
 oversmp.OversamplingStopReset = ADC_REGOVERSAMPLING_RESUMED_MODE;
 hadc1.Init.Oversampling =oversmp;*/
 if (HAL_ADC_Init(&hadc1) != HAL_OK)
 {
 }
 // Configure the ADC multi-mode
 
 multimode.Mode = ADC_DUALMODE_REGSIMULT;
 multimode.DMAAccessMode = ADC_DMAACCESSMODE_12_10_BITS;
 multimode.TwoSamplingDelay = ADC_TWOSAMPLINGDELAY_1CYCLE;
 if (HAL_ADCEx_MultiModeConfigChannel(&hadc1, &multimode) != HAL_OK)
 {
 }
// Configure Regular Channel
 
 sConfig.Channel = ADC_CHANNEL_15;
 sConfig.Rank = ADC_REGULAR_RANK_1;
 sConfig.SamplingTime = ADC_SAMPLETIME_6CYCLES_5;
 sConfig.SingleDiff = ADC_SINGLE_ENDED;
 sConfig.OffsetNumber = ADC_OFFSET_NONE;
 sConfig.Offset = 0;
 if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
 {
 //Error_Handler();
 }
 
 
 HAL_ADC_Start(&hadc2);
 
}
//=============================================================================
/**
@return
- none
 
Initializes adc2
 
*/
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_DIV2;
 hadc2.Init.Resolution = ADC_RESOLUTION_12B;
 hadc2.Init.DataAlign = ADC_DATAALIGN_RIGHT;
 hadc2.Init.GainCompensation = 0;
 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;//ADC_BUFFER_LEN;
 hadc2.Init.DiscontinuousConvMode = DISABLE;
 
 hadc2.Init.DMAContinuousRequests = DISABLE;
 hadc2.Init.Overrun = ADC_OVR_DATA_OVERWRITTEN;
 hadc2.Init.OversamplingMode = DISABLE;
 /*hadc2.Init.Oversampling =oversmp;*/
 if (HAL_ADC_Init(&hadc2) != HAL_OK)
 {
 // Error_Handler();
 }
 
 sConfig.Channel = ADC_CHANNEL_17;
 sConfig.Rank = ADC_REGULAR_RANK_1;
 sConfig.SamplingTime = ADC_SAMPLETIME_6CYCLES_5;
 sConfig.SingleDiff = ADC_SINGLE_ENDED;
 sConfig.OffsetNumber = ADC_OFFSET_NONE;
 sConfig.Offset = 0;
 if (HAL_ADC_ConfigChannel(&hadc2, &sConfig) != HAL_OK)
 {
 //Error_Handler();
 }
 
 
 
 
 /* USER CODE END ADC1_Init 2 */
 HAL_ADC_Start(&hadc2);
}

I've attached a picture of the data for reference. Thanks!