Dual ADC mode single DMA configuration - How?
The STM32H7(4/5) documentation states that two of the ADCs on board can be used in dual ADC mode, so that their 16bit samples are read into the upper- and lower halfwords of a single 32bit register (ADCx_CDR), from where a single DMA can read them into designated buffer array.
The documentation states this in no uncertain terms:
" A single DMA request is generated each time both master and slave EOC events
have occurred. At that time, the slave ADC converted data is available in the
upper half-word of the ADCx_CDR 32-bit register and the master ADC converted
data is available in the lower half-word of ADCx_CDR register. "
There is no example, documentation, or publicly available implementation of this that I could find, and making the above happen has proven impossible to me and my colleagues. The DMA setup is straightforward, but the ADCs still read data into their respective registers, and not into a common one, or if there is a separate common register, it isn't apparent how to point the DMA there.
I'd be extremely thankful of any help, be it pointing towards examples, or working code snippets for this. Here is the ADC1 initialization segment, where I suspect the issue lies:
hadc1.Instance = ADC1;
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 = DISABLE;
hadc1.Init.NbrOfConversion = 1;
hadc1.Init.DiscontinuousConvMode = ENABLE;
hadc1.Init.ExternalTrigConv = ADC_EXTERNALTRIG_T2_TRGO;
hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_RISING;
hadc1.Init.ConversionDataManagement = ADC_CONVERSIONDATA_DMA_CIRCULAR;
hadc1.Init.Overrun = ADC_OVR_DATA_OVERWRITTEN;
hadc1.Init.LeftBitShift = ADC_LEFTBITSHIFT_NONE;
hadc1.Init.OversamplingMode = DISABLE;
if (HAL_ADC_Init(&hadc1) != HAL_OK)
{
Error_Handler();
}
/** Configure the ADC multi-mode
*/
multimode.Mode = ADC_DUALMODE_REGSIMULT;
multimode.DualModeData = ADC_DUALMODEDATAFORMAT_32_10_BITS;
multimode.TwoSamplingDelay = ADC_TWOSAMPLINGDELAY_1CYCLE;
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_DIFFERENTIAL_ENDED;
sConfig.OffsetNumber = ADC_OFFSET_NONE;
sConfig.Offset = 0;
sConfig.OffsetSignedSaturation = DISABLE;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
{
Error_Handler();
}And DMA initialization seems to happen inside ADC init.