STM32H750 internal temperature sensor wrong reading

[Serge76]

Dear community,

on the ADC3 IN18 (internal temperature), I have an unconsistancy between the output of the ADC (reflecting the value of the temperature and the reference value TS_CAL1 and TS_CAL2 (0x3114 and 0x40C0).

the ADC is in 16 bits and I got a value from the ADC 0xA152.

When using the formulae converting the value from ADC to temperature, the result give 685 °C !!!!

I change the conversion scale to 12 bit, and now the result is -163°C.

it seems the reference value are fix whatever the ADC scale range. but nowhere I found a formulae explaining the influence of the conversion scale neither the influence of Vref.

we extend the sampling time to comply with the minimum 9 µs.

[MarkvdBurg]

Hmm good point. I'm a bit new to these microcontrollers. right now im using the Arduino giga r1 wifi which uses the STM32H747XI and im trying to get the temperature from the temperature sensor within the microcontroller for fan speed adjustments based on the microcontroller temp etc.

[Serge76]

Hi MarkvdBurg,

When eveluating why we were not able to record the correct CPU temperature, and thank to the community to help us in this task, we forget to set the TSEN and VREFEN.

Without them, there is not stable voltage value, then impossible to record correct voltage representing the CPU temperature.