Eth_air_controller is a project mainly written in C and ASSEMBLY, it's free.
Control Air Conditioner via internet using ATmega328P
This code can be controlled air conditioner via internet on ATmega328p with ENC28J60.
make main usage: access to http://hostname/pc or http://hostname/m request need to send to /ir Format: /ir?power=<on|off>&temp=<20-30>