Hi,
This will ring a bell to radioamateurs (HAM radio) but other may just ignore...
I have posted to my blog a code for a simple VFO (Variable Frequency Oscillator) or better said an RF frequency generator using an AD9850 DDS chip.
This code is simple and has no special trick but might give you inspiration.
http://xv4y.radioclub.asia/2013/03/19/code-source-vfo-avec-dds-ad9850ad9851-et-launchpad-msp430/
The pins are "wired" for my WSPR agile beacon generator kit, but everything can be changed to your taste or needs.
The text of the blog article is in french but has no additional