Audio Frequency Spectrum Analyzer & Spectrogram

As a followup to a previous post on Music Visualization with Processing (and a good excuse to play with my Arduino), I decided to convert my Processing music visualizer into hardware. The project is not finished yet, but I wanted to post a quick update and how-to on making what I have so far.

 

Media

Here a picture and video of the current working setup:

 

Video

 

Info

An Arduino Duemilanove is used to sample sound through an anlog pin, compute the FFT of the sample, and visualize the audio on an LCD display. The center of the display shows the current frequency waveform plot, while a small-scale spectrogram is drawn on the left.

The original idea for this project was to make an audio spectrogram using an Arduino and an LCD. I wanted to use the full LCD for a nice big spectrogram graph. You will notice, though, in the picture and video above, that the spectrogram is a bit tiny and shares screen space with a frequency spectrum visualizer.

The spectrogram portion drawn is currently as large as can be because of memory limitations on the ATMega328 chip! (well, at least in the current version of the code). The spectrogram is stored as a 64×12 matrix where each column (12) is a stores the values (64) of the signal’s frequencies. 64 is the height of the screen, but 12 is far from the width (128), so I decided to fill the blank space with the waveform plot.

The spectrogram driver code is simply a modified version of my Processing app, and the frequency spectrum waveform plot is a modified version of this project’s code.

Mic pre-amp

This is a modified circuit from [here], with an added potentiometer (R5) for gain control.

R5: controls the gain.   Vout: to Arduino Analog Pin 5.   OP1: LM741 op-amp.

 

LCD

Buy from Adafruit: KS0108, and use the following wiring pinout:

More info: KS0108 Documentation

 

Code

Get My Arduino frequency analyzer + spectrogram source code and try it out for yourself!

You will also need: Arduino FFT source code & the GLCD/KS0108 Library.

Similar Project: Arduino audio analyzer (w/ VGA out)

 

Pics

 

Future work

This project is far from done! I plan to eventually move everything off the breadboard, re-wire and solder the components to a real circuit board, and fit everything nicely into a small box. Meanwhile, it would be nice to find a workaround for the non-fullscreen spectrogram; if I can’t, it is fun to experiment with different ways of visualizing sound on this device. Maybe adding the ability to choose between a mic or ‘line-in’ jack would be cool too.

Thanks for reading – Please share if you enjoyed this post, and good luck if you plan to try it out yourself!