unreality

Continuing from my last post, I’m going to do a brief post on the spectrum analyzer prototype.

Once I received my free MAX7219 samples and got the necessary electrical components, I bagan to construct the 8×8 LED matrix. After what I thought was a lot of soldering (more on this to come…) I had a completed 8×8 blue LED matrix consisting of 64 individually addressable LEDs. After doing some preliminary tests with static routines, I whipped up a simple spectrum analyzer in Processing and implemented a basic serial communication protocol between the Arduino (which was controlling the MAX7219 chip) to send the audio levels to the matrix. And here are the results:

Since creating the LED matrix prototype, I’ve been casually working on a more sophisticated graphical interface to easily display audio spectra, patterns or user input using a serial USB connection. It’s coming along nicely, and I’ve been working on making it as versatile as possible to accomidate various sizes of matrices.

My idea was to have these smaller, modular 8×8 panels that could literally be hooked up together in any shape and ultimately be controlled via a serial connection of some sort. After lots of discussion on the SparkFun forums there was a general consensus that these small panels might not be the way to go for a larger scale (poster size) display that I had in mind… So I began my search on the internet for alternative methods for driving larger displays. Unfortunately my experience with electronic circuits is limited so I did not have the luxury of designing my own, which would have been nice but hey what can ya do. Then I found the Peggy 2.0 from Evil Mad Science and bingo, I had found what I was looking for.

The Peggy 2.0 is a 25×25 LED display (totaling 625 individually addressable pixels!) that is controlled by an ATmega168 (same microprocessor as the Arduino). I ordered 2 of them, because I would like to put them side-by-side to create a widescreen display. Thankfully the Peggy 2.0 was designed with horizontal scaling in mind and allows for them to be placed horizontally without any visible deadspace.

I also decided to go with the 10mm LEDs because the pixels are bigger and closer together which I felt looked really good in the pictures and video I had seen.

Anyway, the two Peggy boards and blue 10mm LEDs (from China) have arrived, and I will post pictures soon.

The first step is admitting you have a problem, right?

Well my problem has to do with these little semiconductor diodes that emit all sorts of wonderful colours of light. That’s right, LEDs. I love them and I can’t get enough of them.

So I had a bag of 500 blue LEDs from a 2006 PC case mod idea that was never realized and had essentially collected dust for a year while at university. Then last summer I had an idea to make an LED spectrum analyzer (like this) and started doing some research. I came across the SparkFun forums and started asking questions and received a lot help. Since I already had the LEDs, all I needed was a way of making them do my bidding.

Enter Arduino. A fantastic “open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It’s intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments.” Perfect!

So after some discussion on the SparkFun forums, I got my idea rolling with a shiny new Arduino and a few free samples of the Maxim MAX7219 chip:

Then after some breadboard rearranging and some extra coding time:

The communication between the Arduino and the MAX7219 (which was driving the row of 8 LEDs) was made possible by the LedControl library available on the Arduino Playground.

In part 2 of this post I’ll be talking about the LED spectrum analyzer prototype.