First of all, here is what I'm building:
It's a multi-touch music controller. The black stripes down the middle of each column are touch-sensitive strips. The leds provide visual feedback of touch input as well as displaying animations based on the host music software. The real thing will use just one color of led, not 2-color as shown in the concept sketch.
I have built a little prototype with Arduino and code from Tomek, Wayoda, et al, modified:
xenome: meanwhile, back at the lab... - YouTube (watch all the way to the end to see the touchstrip in action)
Now I have designed a couple of circuit boards:
The first board holds 112 10-segment led bar-graph arrays. 7 in each column = 70 leds, then I leave the top 3 and bottom 3 out of the circuit to get 64 LEDs per column.
The second board holds 16 MAX7221 driver circuits. I've routed the traces to the edges of both boards so I can stack the led board on top of the driver board and connect them together with header pins/sockets.
Now I need to figure out how much power this will need and how to build a power supply.
I found this power supply cookbook on MAXIM's site: http://www.maxim-ic.com/cookbook/powersupply/ , but I'm not sure what I need. I saw elsewhere on this site that I will probably need 3 Amps to power all of the MAX7221s, but I'm not sure how this will work, exactly. Do I need to route 4.5V to each MAX7221 individually? Should each driver circuit be on it's own ground plane/power plane, or can they all be connected together? Is there an off-the-shelf power supply that will work for the prototype? Any and all help appreciated as I am into this thing WAY over my head! :o
Note: I see some people on this site are working on projects driving large #'s of LED so hopefully this will be useful/inspirational/cautionary for others.