Saturday, December 10, 2011

Festive and Nerdy

You might have seen those big outdoor displays where every pixel is composed out of a little three-color LED light. In this post I'll tell you how I turned a string of those pixel lights into Christmas tree lights!

Adafruit industries, one of my favorite suppliers, recently started selling strings of a particularly advanced model of these pixel lights. Have a look at the product image, and tell me if it doesn't already look like a string a Christmas tree lights..
"12mm Diffused Digital RGB LED Pixels"
As you might have seen in my previous post, these pixels are rather easy to control from a micro-controller. However, stuffing a breadboard in your tree is not exactly festive. Thankfully, you can get these handy little tins that are just about the right size for a wall-wart plug, a teensy 2.0 with female headers (courtesy of Pieter Floris) and a big mess of wires.

A wall-wart plug, a Teensy2.0 and a big mess of wires.
Note that, thanks to the female-pin Teensy, everything is wired up using jumper wires. That's right - this is a no-solder project. Because the underside of the Teensy is not isolated, and because I have a number of wires in there that might come loose, I have isolated the interior of the tin using electrical tape. This is most likely not compliant with any code enacted after 1953 or so, so any imitation is purely at your own risk.

The only remaining question is how to fasten the plugs and wires onto the enclosure. Ideally you would use specially molded plastic caps and bits, but the odds of finding them in the right size and shape at your local hardware store are quite slim. Instead, I liberally applied black sugru around the holes I had cut into the tin, and then pressed the wires and the plug into it. The sugru just molds around the objects. After a quick touch-up I left it to cure overnight, and the result was really really good.

Now we just pop closed the tin and voila, a presentable programmable Christmas tree lights driver!

The controller and a single string of LED pixels, running a test pattern.
And here's the tree, all festive and nerdy:

Festive and Nerdy

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