While I've been waiting for the final parts to arrive (LEDs, SO-DIP-Adapter, ICs, etc.) I did some more theoretical work and tried to scale the 3x3x3 driver circuit to 8x8x8.
This is the result:
|From LED Cube Images|
This circuit diagram also shows one specific feature of my cube. I want to transmit the LED status via serial connection to the driver ICs but in contrast to eg. the solution on HNTE I want to transmit the serial data to all driver ICs in a concurrent fashion, not via chaining them. It should work by providing all ICs with the same clock and latch signal but running a seperate signal from the Raspberry Pi's GPIO to each IC's serial input. That way I can set up the configuration for a single layer with only 16 clock cycles instead of 64. I'm not sure if this works as expected. If not, I'll have to fall back to daisy chaining the ICs serial lines.
That's why I also tried to come up with a flexible solution for the software which allows me to quicly adapt the serial output if I have to change the circuit. My goal is to create an algorithm which determines the required clock/serial/latch output in an efficient way from an 8x8x8 LED status array. It should also be easily configurable so that I can port it from the first 3x3x3 prototype to the final 8x8x8 cube with minimal changes even if I have to change the driving circuit.
I had no success so far though which may or may not be related to the fact that I only found time to think about that in the past week after 11pm each day as I've been busy with other stuff earlier each evening.| Permalink