Code generation - ADC3 prescaler

[heveskar]

In the IDE GUI, when selecting asynchronous clock division for ADC3 on STM32H747XIH, the value generated in the code seems to be taken from ADC1, e.g.:

ADC1 (divided by 4):

ADC3 (divided by 6):

generated code (shortened):

/* ADC1 init function */
void MX_ADC1_Init(void)
{
...
  hadc1.Instance = ADC1;
  hadc1.Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV4;
  hadc1.Init.Resolution = ADC_RESOLUTION_12B;
  hadc1.Init.ScanConvMode = ADC_SCAN_ENABLE;
  hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
  hadc1.Init.LowPowerAutoWait = DISABLE;
  hadc1.Init.ContinuousConvMode = DISABLE;
  hadc1.Init.NbrOfConversion = 2;
  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_PRESERVED;
  hadc1.Init.LeftBitShift = ADC_LEFTBITSHIFT_NONE;
  hadc1.Init.OversamplingMode = DISABLE;
  if (HAL_ADC_Init(&hadc1) != HAL_OK)
  {
    Error_Handler();
  }
...
}
/* ADC3 init function */
void MX_ADC3_Init(void)
{
...
  hadc3.Instance = ADC3;
  hadc3.Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV4;
  hadc3.Init.Resolution = ADC_RESOLUTION_12B;
  hadc3.Init.ScanConvMode = ADC_SCAN_DISABLE;
  hadc3.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
  hadc3.Init.LowPowerAutoWait = DISABLE;
  hadc3.Init.ContinuousConvMode = DISABLE;
  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_DR;
  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();
  }
...
}

This is for project generated with STM32CubeMX v6.10.0. For project generated with STM32CubeMX v6.11.0, prescaler value for ADC3 is not even filled at all.

IDE version: 1.15.0

STM32CubeMX version: 6.11.0

[STTwo-32]

Hello @heveskar 

Think you for reporting this issue. I will escalate it intenally to the concerned team for correction.

Best Regards.

STTwo-32 

[AScha.3]

The ADCs have only one common clock/prescaler here :

So the setting can be only one for all ADC 1,2,3 .

(read in rm...)

btw

@STTwo-32 , i think " escalate it intenally " will not change this . 🙂

[STTwo-32]

Hello @AScha.3 @heveskar 

Thank you for this information. I'm checking this internally for more details and i will be back to you as soon as possible.

Best Regards.

STTwo-32 

[heveskar]

@AScha.3 It doesn't seem so clear to me, if you look at the register description, RM first states that CCR is common for ADC1 and ADC2 and ADC3 is controlled separately:

and then for the CCR.PRESC value, it states that all the clocks are really common:

And ADC3 really has separate CCR register and different value can be written to the PRESC field:

But if it really is common, the GUI configuration tool should force the same value for ADC3 and  ADC1 (this binding is already there for ADC1 and ADC2).

[STTwo-32]

Hello @heveskar 

As i said before. I'm checking this internally and i will be back to you on monday with more clarifications.

Best Regards.

STTwo-32 

[STTwo-32 · Accepted solution]

Hello @heveskar 

The problem is a CubeMX generation that i've reported internally to the concerned team under internal ticket number 179287. The Figure that @AScha.3 shared is commun for each ADC interface (ADC1, ADC2 or ADC3) and not for all three of them.

Best Regards.

STTwo-32