First I haven't built a 3D printer but I've been researching for weeks. Been following this thread with interest as I just don't want to spend money on an AVR when ARM looks it's starting to take off. Did programming in the past with 8051's and would prefer to not play 8-bit tricks again. Couple of interesting links to help: Link to using the 16u2 as EEPROM on the DUE. DUE EEPROM Really love thby Grey - Controllers