I've been following sites like ComputerChristmas and PlanetChristmas because they have neat ideas to control christmas lights (or anything I suppose) with a computer.
I'm just wondering if it would be possible to do it without the computer, using an arduino. With a computer, they generally use the serial port, and there's ways to get a bunch of "channels" by combining ports (to my understanding), so you're not just limited by the number of pins in your serial port. I'm thinking just hook up the arduino outputs to a controller and follow the rest of the normal steps.
The problem I'm seeing is the space on the chip, which if I'm not mistaken from my day of research, is 16k. If I had, say 16 channels, and everyone of them is getting a high/low command every half second for say 2 minutes, would that code fit on the chip?
Also, any ideas to make sure an audio file starts playing at the exact time the "score" starts on the arduino? Syncing lights with music is important.
It's worse than that as the 16K isn't all available to use. So that's where you start to get clever and look into compression of the data. There are lots of directions this could go but assuming you don't want a desktop (or laptop) computer involved in any way (remember the Arduino is a computer) and you can start / stop the music with a logic level you could code things for each light with a byte for each light that says how many half second cycles to go before changing state. This runtime encoding is like the compression in GIF images.
You might be better writing an application in say processing, so that you define your light show like a music application and then it generates a compressed file to down load to your Arduino.
Another option is that you could use the Arduino to generate MIDI data for a MIDI voice unit and have the lights go with that.
Lady Ada has a wave shield for Arduino that allows playback of audiofiles, controlled from Arduino. But you would still need some kind of amplification.
It's built with an SX28 but designed to be controlled by a microcontroller. It will handle up to 128 channels with additional boards. Parallax Inc | Equip Your Genius®
I'm just wondering if it would be possible to do it without the computer, using an arduino.
The Arduino is a computer. To answer your first question, it's impossible to have computer controlled christmas lights without a computer. By definition.