This is a very early alpha version for using ATxmega128A3U as an AVRISPMKII.
This project is based on the AVRISPMKII from the LUFA library.

At the moment only PDI programming is rarly supported.
But it already can be used to program other ATxmega.
ISP and TPI is not implemented, yet.

You also might experience some instabilities - please reset the device
before every retry.
Also ensure to properly connect the target and make sure every Vcc and
GND pin is supplied (and buffered).

The PDI port on the ATxmega is USARTE1:
Please connect the TX1 (PE7) with the RX1 (PE6) pin via an 220..470 ohm resistor.
Then the same RX1 line is connected to the PDI port of the target AVR.
The REST/PDI of the target AVR is connected with the XCK1 (PE5) PIN of USARTE1.

If you like you can add 2 LEDs to PF6 and PB7:

  PF6: activity inidcation (toggles each command)
  PB7: direction indication - high if TX is enabled
  

Stephan Baerwolf (matrixstorm@gmx.de), Schwansee 2014