Wednesday, December 2, 2009

AVR Based Direct Digital Synthesis

Microcontroller Project AVR Based Direct Digital SynthesisSometimes you need signal generator for your electronic project. You could build your own Direct Digital Synthesis based on microcontroller. It uses AVR ATtiny 2313 as the main microprocessor. This project design by jesper.
What you get from this DDS? This circuit can generate Sinewave, Sawtooth, Trangle and Sqare-waves ranging from 0.07 Hz to about 200-300 kHz in 0.07 Hz steps (depending on microcontroller crystal).

The circuit contain Just 4 major parts. A voltage regulator/switch, a RS232 interface chip, the 2313 and the R2R resistor network. The R2R network that connected to PORTB ( AT tiny 2313 ) making a simple D/A converter and makes it possible to output 256 voltage levels. Neither the resistor network or port drivers of the 2313 is of perfect linearity, but it works pretty well anyway. But you'll probably need a buffer stage as the output impedance is rather high (tens of kOhms in my case). The MAX603 handles the voltage regulation as well as the powerup/shutdown function, and is controlled by the DTR signal on the serial interface. So when you shut down the control program on the PC, the miniDDS will be shutdown, saving battery.

Download : Schematic, ASM code, Windows Control Program

related search : AVR project, Direct Digital Synthesis, Microcntroller Signal Generator (src)