SAADC reference voltage

[Sundar_santhanam@1998]

Hi, 

Is it possible to give 3.3V to the Vdd pin of my nrf52840 to change the reference voltage of saadc to 3.3V ? Do I have to change any configurations for the same?

[Turbo J]

The only available references for the SAADC are VDD/4 (VCC/4) and 0.6V internal.

[Sundar_santhanam@1998]

im going to power up my board using USB power supply which is 5V and so is it 5/4?

[Turbo J]

Nope: Read the PS.

[Monty]

That doesn't seem to be true though! From the nRF52840 docs page check pages ~126 and notice that registers EXTREFSEL and REFSEL can be used to set external reference on all analogue pins A0-A7.

[Turbo J]

That chapter talks about the COMPerator and not the SAADC peripherial.

You can compare to an external voltage, but cannot use it for the SAADC reference.