ESP32-MINI-1 ADC calibration, accuracy and repeatability

[ma-lalonde]

Hello! I am designing with the ESP32-MINI-1, and I have two questions regarding the ADC.
I have already read the documentation and this thread: viewtopic.php?f=19&t=2881

1. Is the ESP32-MINI-1 ADC VREF value calibrated and burned in eFUSE during fabrication? Datasheet does not mention that the U4DWH is calibrated, but forum posts typically mention "chips made after 2018-06-01", so I wonder.

2.Are the ADC non-linearity curves similar (< 1%) between all chips? I'd like to make a sensor driver where I can hardcode a single corrective polynomial that works for all boards.

3. If the answer to either one of these is no, is there a recommended calibration method that could yield good results for mass production? I am already making a validation board, if I can add a precision DAC / ADC to it and do an auto-calibration at the same time, I'll be happy.


Cheers,