Flexible DDS function generator
Andreas Schwarz have built an AVR DDS generator which can generate Sine, Rectangle, saw signals from 0.5Hz to 25kHz. Frequency can be changed in 0.5Hz steps.
Signal generator also has amplitude(0-10V) regulation feature with offset(-6V to +6V) adjustments. Whole control program is written in asm language, what makes it compact and optimal.