This project allows you to create your own square wave signal generator with a nice GUI interface. The GUI is written in QT and work on Windows Linux and Mac.
This GUI controls the AD9850 DDS chip, the modules of which can be bought from eBay for a few dollars. The AD9850 is connected to an Arduino and the Arduino is connected to the PC via a serial port. The Arduino I used was an Arduino Uno. The AD9850 chip prefers to be powered from 3.3 V while the Arduino Uno outputs 5 V logic. I placed current limiting resistors between the Arduino and the AD9850 module and connected the power of the AD9850 to the 3.3 V output of the Arduino Uno; this can be seen in the following figure.
The five dollar AD9850 modules look like following.
Using an SDR-RTL TV dongle using SDR-Sharp and tuning into
around 32 MHz I got the following when I clicked on enable a few times.
The Arduino sketch needs my SLIP library from http://jontio.zapto.org/hda1/SLIP_library_for_Arduino.html and also the AD9850 library found from https://code.google.com/p/ad9850-arduino/downloads/list .
For the GUI I shall only include source code so you will need to obtain Qt https://www.qt.io/download-open-source .