STM32U5 ADC internal channel

Hello,

I'm facing some issues sampling ADC internal channel in of STM32u575.

In particular these are the steps I'm following:

VDDA enable

ADC Clock Configuration

HAL_ADC_Init (&ADC_Handle[i])

Interrupt configuration.

Then, I configure the ADC channel to read VREFINT and start a conversion, which is ok.

After that, when configuring ADC channel to read the internal temperature sensor, even if the function HAL_ADC_ConfigChannel returned ok, the temperature read value had no sense (-240°C which is just a little bit too cold).

I found out that by looking into config channel function that:

   /* Parameters update conditioned to ADC state:               */

   /* Parameters that can be updated only when ADC is disabled:        */

   /* - Single or differential mode                      */

   /* - Internal measurement channels: Vbat/VrefInt/TempSensor        */

   if (LL_ADC_IsEnabled(hadc->Instance) == 0UL)

This condition prevents me to configure internal channel id ADC is already enabled, however it does not return any error if the condition is met.

So, I was wondering if this is the right behaviour and if it is stated somewhere in the reference manual as I found out that bypassing these checks:

   if (LL_ADC_IsEnabled(hadc->Instance) == 0UL)

if(__LL_ADC_IS_ENABLED_ALL_COMMON_INSTANCE(__LL_ADC_COMMON_INSTANCE(hadc->Instance)) == 0UL)

I get a correct temperature reading.

For now I'm disabling the ADC every time I need to change internal channel to ensure a correct reading.

Best regards,

Matteo