@njbuch said: @Stephan35 Indeed but my voltage divider used was aiming for 0.0 - 3.3 and resulting output was over 1 volt most of the time, which means that I am reading 65535 all the time. I need a new one. I am looking in my bins after a few resistors that matches my photo-resistor specs. Will revert when successfull. I am using: http://www.ohmslawcalculator.com/voltage-divider-calculator to find the right combination. Sorry, answer is there : analogRead(A0) return 65535 You have to modify Myconfig.h #define ENABLE_READ_VCC