Xmega32 E5 DDS Sine Wave Signal Generator Example

JC · Joined: 15 Dec 2007 Posts: 627 Location: Cleveland, OH

The following is a simple DDS Sine Wave Generator for the Xmega E5 series.

It is not a Direct Digital Synthesis tutorial, but if you are familiar with the concept it should make sense.
Basically one has a signal lookup table, (Sine, Square, Triangle, etc.), and runs an ISR at a fixed, fast, rate.
One calculates the next sample to output based upon the desired output frequency, table size, and DAC update rate.

This program is set up for a 62.5 kHz DDS ISR, (sample update rate).
The number of samples the output signal has is fixed at 62.5 k samples / Second.

A 1 Hz sine wave would have 62.5 K samples for one Period of the sine wave.
A 1 KHz sine wave would have 62.5 samples per one Period of the sine wave.
A 10 KHz sine wave would have 6.25 samples per one Period of the sine wave.

Know that even a simple first or second order Low Pass Filter will significantly clean up the output signal by removing the higher frequency components of the "stair-step" signal.

There is certainly room for improvement, but this demonstrates a working example of the concept.

JC

albertsm · Joined: 09 Apr 2004 Posts: 6197 Location: Holland

thanks for sharing Very Happy