Grumpy_Mike:
Am I right in thinking that for each plane you have a sepreate cathode connection and that all the cathodes are not connected together on each plane? Otherwise it would never work would it.Have you done any tests to see how these LEDs look when they are on, if you need diffusers or what current you need to run them at.
Once you know the current for each LED you can then work out how much current to sink with the cathode sinks, you might need a FET here.You then can look into how to provide that current at the anodes.
You are correct about the each plane having a separate cathode connection (4 cathodes, 48 anodes), but all the cathodes per plane are connected (thats 48 cathodes tied together per plane as the LEDs have 6 leads)
I did many tests on the LEDs at 3.3vs to figure out the forward voltage on the LEDs. I figure at 5vs I would need about 100 ohm on the red, 150 on the blue/green. At 3.3v, I need around 50-75 ohms on the red, and maybe something on the blue, im not too sure. I had a an LED hooked up to the 3.3v with a couple resistors, with the 3 leds lit, it seemed a bit blue, and Im guessing that it should be white.
Nearest I can tell, the forward voltage on the red is 2.15, and the blue and green are about 3.3v (That is to say, if I want 20 ma per LED, then those are the approximate voltages)
I have been experimenting with making some voltage dividers to try to hook up some shift registers, to get them to output 3.3v my lack of parts is making it hard, but I have found bunch of tiny 4.7k resistors, and I'll be messing around with them this morning.