Arduino ATmega16U2 USB chip firmware

Sources

• hardware/arduino/avr/firmwares/atmegaxxu2 at https://github.com/arduino/Arduino
• firmware/atmega16u2 at https://github.com/Pinoccio/hardware-pinoccio

Default settings

• The makefile flags set for Uno Rev 3

How to build

# DFU bootloader
(cd Bootloaders/arduino-usbdfu && make clean && make)
# USB serial firmware
(cd Projects/arduino-usbserial && make clean && make)

Note very well

• The LUFA version is 100807, as in the hardware-pinoccio repository. This version is required for both DFU and USB serial firmware.

References

• LUFA source: https://github.com/abcminiuser/lufa

Notes excerpted from the Arduino firmware distribution

See https://github.com/arduino/Arduino/blob/master/hardware/arduino/avr/firmwares/atmegaxxu2/README.txt

• The arduino-usbdfu directory contains the DFU bootloader on the 16U2
• The arduino-usbserial directory contains the actual usb to serial firmware
• Both should be compiled against LUFA 100807

To burn a hex file:

avrdude -p atmega16u2 -F -P usb -c avrispmkii \
  -U flash:w:output-file.hex \
  -U lfuse:w:0xFF:m -U hfuse:w:0xD9:m -U efuse:w:0xF4:m \
  -U lock:w:0x0F:m

Notes on USB Vendor IDs (VID) and Product IDs (PID)

The arduino-usbdfu project uses Atmel's VID and MCU-specific PIDs to maintain compatibility with their FLIP software. The source code to the arduino-usbserial project includes Atmel's VID and a PID donated by them to LUFA. This PID is used in LUFA's USBtoSerial project, which forms the basis for arduino-usbserial.

According to the LUFA documentation, this VID/PID combination is:

"For use in testing of LUFA powered devices during development only, by non-commercial entities. All devices must accept collisions on this VID/PID range (from other in-development LUFA devices) to be resolved by using a unique release number in the Device Descriptor. No devices using this VID/PID combination may be released to the general public."

The production version of the arduino-usbserial firmware uses the Arduino VID. This is only for use with official Arduino hardware and should not be used on other products.

License

MIT. See LICENSE.