Building the Mini Direct Digital Synthesis (DDS)

With the use of the AT90S2313 and a resistor network, this project can create a simple version of Direct Digital Synthesis (DDS).

This mini DDS is a simple version which uses only the 2313 and and resistor network as compared to other simple sine wave generator which are based on an Analog devices AD9832 chip. This design can generate different waves such as Sine, Sawtooth, Triangle, and Square with a range from 0.07 Hz to about 200-300 kHz in 0.07 Hz steps while being controlled via RS232 from a small Windows program.

There are 4 major parts that comprise the design which include the R2R resistor network, the 2313, an RS232 interface chip, and a voltage regulator/switch. A simple D/A converter is made by connecting the R2r network to PORTB on the 2313. This makes it also possible to output 256 voltage levels. It works pretty well even if neither the resistor network or port drivers of the 2313 is of perfect linearity. The voltage regulation and the power-up and power shutdown function are handled by the MAX603 that is controlled by the DTR signal on serial interface.

Rest of the project