Xmega128a1 arduino uno - Ethernet Booster Pack v3 - Booster Packs - 43oh
Installing an Arduino Bootloader Here we have the Arduino Uno R3. It has two ICSP headers: one for the ATmega16U2 and one for the ATmega328.
Arduino Uno Rev 3 and mega2560 Rev 3 both break out separate TWI connections that aren't in the pinout for the earlier Xaduino Xmega128A3U; Xmega.
Pocket AVR Programmer Hookup Guide The ATmega328 on an Arduino Uno or RedBoard works perfectly, but the ATmega2560 of an Arduino Mega does not.
XG7100: XGraph AVR ATXmega Single Board Computer with Touchscreen LCD