I trace this back to the call tmp_hal_status = ADC_Enable(hadc) in HAL_ADC_START_DMA() in stm32h7xx_hal_adc.c.
When I look into ADC_Enable(), I see comment about a workaround.
There is waited for ADC_ENABLE_TIMEOUT. But with the settings I use, this ADC_ENABLE_TIMEOUT (2) is not enough. There need to be a delay of at least (3) to have succes.
I'm using a very low clock for the ADC, this should be the reason. But the comments in "stm32h7xx_hal_adc.c." suggest this is already taking into account.
please explain why this still gives HAL_ERROR?
For the time being I use a loop tho check ADC_Enable(&hadc3) or can increase ADC_ENABLE_TIMEOUT . The last can be tricky when the HAL layer is updated.
Input frequency HSE: 25Mhz
SYSCLOCK: 200Mhz
ADC clock mux: 2Mhz (by PLL3R)
Used settings based on cubeIde code:
void MX_ADC3_Init(void)
{
ADC_ChannelConfTypeDef sConfig = {0};
/** Common config
*/
hadc3.Instance = ADC3;
hadc3.Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV256;
hadc3.Init.Resolution = ADC_RESOLUTION_16B;
hadc3.Init.ScanConvMode = ADC_SCAN_DISABLE;//ADC_SCAN_ENABLE;
hadc3.Init.EOCSelection = ADC_EOC_SEQ_CONV;
hadc3.Init.LowPowerAutoWait = DISABLE;
hadc3.Init.ContinuousConvMode = ENABLE;
hadc3.Init.NbrOfConversion = 3;
hadc3.Init.DiscontinuousConvMode = DISABLE;
hadc3.Init.ExternalTrigConv = ADC_SOFTWARE_START;
hadc3.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
hadc3.Init.ConversionDataManagement = ADC_CONVERSIONDATA_DMA_CIRCULAR;
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_VBAT;
sConfig.Rank = ADC_REGULAR_RANK_1;
sConfig.SamplingTime = ADC_SAMPLETIME_387CYCLES_5;
sConfig.SingleDiff = ADC_SINGLE_ENDED;
sConfig.OffsetNumber = ADC_OFFSET_1;
sConfig.Offset = 0;
sConfig.OffsetRightShift = DISABLE;
sConfig.OffsetSignedSaturation = DISABLE;
if (HAL_ADC_ConfigChannel(&hadc3, &sConfig) != HAL_OK)
{
Error_Handler();
}
/** Configure Regular Channel
*/
sConfig.Channel = ADC_CHANNEL_TEMPSENSOR;
sConfig.Rank = ADC_REGULAR_RANK_2;
sConfig.Offset = 1;
if (HAL_ADC_ConfigChannel(&hadc3, &sConfig) != HAL_OK)
{
Error_Handler();
}
/** Configure Regular Channel
*/
sConfig.Channel = ADC_CHANNEL_VREFINT;
sConfig.Rank = ADC_REGULAR_RANK_3;
sConfig.Offset = 2;
if (HAL_ADC_ConfigChannel(&hadc3, &sConfig) != HAL_OK)
{
Error_Handler();
}
}
