I've been thinking about building a 12x24 rgb led coffee table. the leds would be in 2" squares, the design is similar to this:
Except that instead of 7x16 its 12x24, this means a lot of multiplexing cause with RGB leds itll actually be 864 leds. Unfortunately I have never done any multiplexing before, but i have a VERY basic understanding of it. I learned most of what i know from this instructible: http://www.instructables.com/id/Led-Cube-8x8x8/ I'm still kinda fuzzy in some areas, like how to write the code for multiplexing and clocking the ICs
Some things I want it to do:
-play tetris (need help on the code for this and the one below, but thats for later)
-play snake (low resolution)
-be able to connect an iPod or other such device and be a VU meter (so split some audio into 12 or 24 frequencies) maybe have an amp and speakers in it too. Or maybe just have a microphone for outside noises and music.
-be able to touch each individual square and have it cycle through colors
The last one is what i need the most help on. The others just need some code help. I had the idea to use photocells in each box, so with the leds on it reads about the same voltage, but if you touch the opaque glass above it it gets a little dimmer, so there would be a drop in voltage( i hope). The way i was gonna multiplex was with 10x 74HC574 ICs. cause ill be using common cathode RGBs and all the anodes for one row will be the on the vertical rows. the cathodes of them all will be connected horizontally. So 9 for vertical(3 for each color) and 2 for the horizontal (with a few pins left over). as soon as i can get to a radioshack i am going to test the photocell idea. I was thinking about reading the photocells with 4051s cause they can read analogs n stuff. Maybe the arduino multiplexes voltages to the photocells in a sort of wave motion, going up one row then down another REALLY fast, then when it sees a change in voltage it cycles to the next color for that square.
sorry that this is so poorly written, any questions please ask. If this seems feasible i would love some construction tips or advice on what would work. Im on a tight budget, so no suggestions like ultrasonic sensors for each square please. the main problem i see is that the reading voltage would be so small it wouldnt be effective, and the lighting in the room couldnt vary at all while in use. I would love some feedback and questions, thanks for looking.