Arduino Uno and Mega 2560 Firmwares for the ATmega8U2 This directory contains the firmwares used on the ATmega8U2 on the Arduino Uno and Arduino Mega 2560. The arduino-usbdfu directory contains the DFU bootloader on the 8U2; the arduino-usbserial directory contains the actual usb to serial firmware. Both should be compiled against LUFA 100807. The two .hex files in this directory combine the dfu and serial firmwares into a single file to burn onto the 8U2. To burn (Uno): avrdude -p at90usb82 -F -P usb -c avrispmkii -U flash:w:UNO-dfu_and_usbserial_combined.hex -U lfuse:w:0xFF:m -U hfuse:w:0xD9:m -U efuse:w:0xF4:m -U lock:w:0x0F:m To burn (Mega 2560): avrdude -p at90usb82 -F -P usb -c avrispmkii -U flash:w:MEGA-dfu_and_usbserial_combined.hex -U lfuse:w:0xFF:m -U hfuse:w:0xD9:m -U efuse:w:0xF4:m -U lock:w:0x0F:m