The goal of this PIC 16F870-based project is to build simple function signal generator that can produce multi waveforms like sine, square, triangle, and saw burst sweep noise. The project uses R/2R resistor ladder network for a real fast and cheap D/A and a few other parts.
All of the sine wave functions utilize a full 256 byte by 8 bit lookup table. It is possible to use a full memory page in the PIC for a lookup table. You can get over 60 kHz of very clean sine waves with the current design running on a 20 MHz clock. The frequency is adjustable in 1, 25, and 500 Hz steps. The unit produces accurate frequencies down to 1 Hz, said Luhan Monat, the project designer.
The signal generator uses three LED as function indicator which vary depending on the type of wave being generated. While the wave function is selected by holding down the select button while rotating the adjustment control. You need to have a scope hooked up to see what you are doing since there is no visible indication of the wave type or frequency.
PIC Signal Generator
Project Detail and Documentation