How to store two differents variables to Arduino EEPROM from PC trough serial communication?
I don’t know if there’s a way to directly read/write the EEPROM without an external programmer (someone correct me if I’m wrong). If you’re looking to store runtime variables, you can use the built-in Arduino library. You could also create a sketch to run once and write those variables to the EEPROM which you can then access later on from another sketch.