Here is a short example demonstrating taking serial string input and storing and retrieving to and from EEPROM. This is done using EEMEM and <avr.eeprom.h>. I also demonstrate using PSTR-like functionality to keep serial response strings in flash but "print" them to serial directly, without copying them into a temp array using PROGMEM.

Also demonstrated is using an eeprom-stored variable to tell whether or not the eeprom has been programmed or cleared. If the stored value does not match, the eeprom is given default values. These default values are stored in flash.