Planet Arduino

Inspired by a project he found over on Instructables, Maker JoEtuuube has created an Arduino-based waveform generator using an 8-bit resistor ladder DAC that can precisely produce different common waveforms at frequencies between 1Hz and 20Khz in sine-wave, sawtooth, triangle and various ratios of square wave. It features a speaker and a small LCD display.

A neat thing about the LCD is that it’s actually a reverse-engineered display from a cheap pocket calculator. With his hack, JoEtuuube no longer punches each digit in directly; instead, he only taps the clear, +, = and 1 keys. He can then enter arbitrary numbers by typing in the right number of ones and adding them up. For example, 345 = 111 + 111 + 111 + 11 + 1.

The generator itself uses an Arduino Uno and runs off a 9V battery. In the video below, JoEtuuube provides a detailed walkthrough of the firmware and how everything works. You can also read more about it on Hackaday.

[Joekutz] wanted to re-build an audio-rate function generator project that he found over on Instructables. By itself, the project is very simple: it’s an 8-bit resistor-ladder DAC, a nice enclosure, and the rest is firmware.

[Joekutz] decided this wasn’t enough. He needed an LCD display, a speaker, and one-hertz precision. The LCD display alone is an insane hack. He reverse-engineers a calculator simply to use the display. But instead of mapping each key on the calculator and typing each number in directly, he only taps the four 1, +, =, and clear keys. He can then enter arbitrary numbers by typing in the right number of ones and adding them up. 345 = 111 + 111 + 111 + 11 + 1. In his video, embedded below, he describes this as a “rather stupid” idea. We think it’s hilarious.

The meat of the project is the Arduino-based waveform generator, though. In the second video below, [joekutz] walks through the firmware in detail. If you’d like a simple introduction to DDS, check it out (or read up our more in-depth version).

He also makes custom detents for his potentiometers so that he can enter precise numerical values. These consist of special knobs and spring-clips that work together to turn a normal pot into a rough 8-way (or whatever) switch. Very cool.

So even if you don’t need an R-2R DAC based waveform generator, go check this project out. There’s good ideas at every turn.

by Annikken @ instructables.com:

This waveform generator is based on the work by Amanda Ghassaei. Waveform generators (or function generators) are used for testing and debugging circuits. e.g. frequency response of op amp or sensors. This waveform generator is powered by Arduino with Annikken Andee shield – a device that lets users create iOS/Android interfaces without iOS or Android programming at all. It outputs sine, triangle, saw and square waves. Frequency is controlled by means of a slider (on iOS/Android device) and wave type is selected using on screen iOS/Android button. With a iOS/Android interface, you can add certain features not possible with hardware buttons. E.g. displaying different ranges of frequencies for each wave type, displaying meaningful controls for certain wave types. For example, the pulse width modulation slider is only visible for square wave types, its not visible for sine, triangle or saw wave forms.

IOS-Controlled Arduino waveform generator - [Link]