This open source firmware for the Atmel XMEGA-A3BU evaluation board is written for use with the cheap AD9850 DDS modules currently available on ebay from China for about $5.00 (Although the one I received had a bad 125 MHz clock oscillator on it, so keep that in mind) The controller firmware is written to provide all the commonly required features needed for a veriaty of possible reciever, transmitter and transceiver projects or as a simple signal generator.
The Atmel eval board is available for $30.00 from distributers like Mouser and Digi-key. This is a credit card sized board which includes the processor, a back lighted 128x32 graphics display, a few switches and SIP header pins for off board connections. Most importently, it has a mini-USB port jack, which can be used to upload new firmware (like that presented here) using a simple boot loader program downloaded to your PC from Atmel.
The features listed below represent those currently available. Additional features may be added in the future, so check back occasionally for updates.
In addition to the XMEGA and 9850 board, you will need a mechanical rotary encoder with Gray code output, preferably also with built-in PB switch, 4 to 5 TACT push button switches and some 2N7000's for level shifting the inputs and outputs to the board.
Full documentation in pdf
Source and hex code for programming eval board. (zip)