/home/vzzbx::signal_generator

 

Introduction

This project is based upon an AD5932 DDS and a AtMega8515 microcontroller. The intention is to build a signal generator which will operate linearly between 10Hz and 10MHz. The AD5932 is capable of generating sinusiodal, triangle and square waves up to 25MHz. This signal generator will have the following specifications:

Background

The DDS is a recent development to create integrated devices that can be used to generate analog signals. A DDS can be created by a simple microcontroller and an A/D converter as is shown in the following circuit. A DDS built from discrete components This particular design is able to reach frequencies of 800 kHz and is only limited by the speed of the microcontroller. The microcontroller carries a wave lookup table and by operating one of the switches one can select which kind of signal is being output. The D/A converter consists of a low-cost, low-performance R-2R resistor network and a buffer amplifier.

The above design is good enough for experimenting with the principals of DDS, but nowadays standard components are available to reach higher performance as is possible using the above circuit.

This led me to the choice whether to continue using a purely software driven DDS generator or to resort to a more sophisticated hardware driven DDS. The hardware driven DDS has so much more advantages over the software driven one that I could not think of staying with the software DDS. The rest of the page will describe will mainly describe the hardware driven DDS.

Software used

The software used in this project will mostly be open source software. All software should be run on Linux in one way or the other as this is the primary operating system I use at home. The circuit and PCB will be designed in gEDA and the resulting data files can be downloaded from this website. The following programs will be used extensively during this developmen cycle:

For simulation I will also use LTSpice, which is a Windows program, but also runs perfectly in wine.

Legal

Copyright (C) 2005 <vzzbx THISISASPAMBLOCKERDEVICE xs4all.nl> This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See file COPYING for more details. This software is released under the terms of the GPL v2.


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