STM32 how to use VREF to Calculate the actual VDDA value

[shasha liu]

Posted on February 10, 2017 at 04:34

I am using the STM32 ADC to caputure outer voltage , while the requirement to  ADC accuracy is not very high. So I decided to use the VDDA as the reference voltage. BUT  the actually vdd added to the mcu exist deviation from each others. Is there any way to get the acutal vdda after reset.?

[Tesla DeLorean]

Posted on February 10, 2017 at 05:40

Most STM32 parts also provide a VREFINT which is an internal 1.25V reference you can sample and use to compute the VREF+/VDDA voltages.

[shasha liu]

Posted on February 10, 2017 at 09:32

Thanks for your replay. 

I still have questions about how to get the VRETINT_CAL mentioned in the datasheet.

thanks

[Tesla DeLorean]

Posted on February 10, 2017 at 15:15

What STM32 specifically are you using they make hundreds of parts in dozen of families, it's like saying you drive a Ford.

The Reference Manual should provide the ROM/OTP address of the memory location holding the VREFINT_CAL value.

I'd start by assuming the voltage is 1.25V, and scaling back up to what a 4095 value would represent based on the reading for VREFINT, and see how close that is to the voltage you can measure with a volt-meter.