ESP32 ADC measurment with variable input voltage?

[orangedays22]

@anon27210439

The easiest way is to put a voltage divider with high value resistors; 1M Omh each. And a ceramic capacitor of 100nF from the middle point to GND, to have enough current for the short readings.

the voltage divider is already done and exactly like you described.
still, even the perfect output of the divider has no use if the reference voltage is not steady