Arduino software in C++ and corresponding iOS app to control vintage NAD equipment over Ethernet and NAD-Link interface.
Ethernet shield is required for this to work. NAD-Link input connects to Ground and Pin-8 on Arduino board.
Parts of NAD-Link code by bitraf: https://github.com/bitraf/nadlink
AVR makefile-base by Markham Anderson: https://gist.github.com/entrity/5424505