Milen @ instructables.com has designed a Function Generator based on the popular MAX038 and is controlled by ATMega328PU. Signal characteristics are displayed on a LCD screen.
The digital features of the function generator were performed by one Atmega328 chip. Its functions are the following:
controls the frequency range selection
controls the signal type (sine, rectangular, triangular, sawtooth)
measures the amplitude of the signal
measures the DC offset
measures the frequency of the signal
measures the THD of the sine signal in the audio range (this still have to be implemented)
displays all this information on a character 16×2 LCD display.
MAX038 Function generator – [Link]