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Help with charlieplexing Answered

Hi all,

I recently decided I want to make something fun again, and then I came across the LED cubes.

I would like to build a handful of 5x6x5 LED cubes, I haven't actually built any yet, only in simulation thanks to Proteus. My first attempt was a single 6x5 grid (30 leds using 6 i/o pins), which was then scaled up 5 times, ie 5 sets of 6x5 grids. (150 leds, 30 i/o pins)

All this works fine, but seems a bit of a waste when i need a few of these cubes and I could run the whole cube off 13 pins as one big charliplexed grid.

However the problem arises that I cannot visualise how the actual cube itself is built. I have no problems drawing a schematic to connect up the 156 led charliplexed grid, it's just the construction that baffles me.

The Christmas Tree indistructable is the best one I can find, but still it is not entirely clear. Maybe it would help if the LED's were numbered. Do they run in sequence? ie, If I you arrange a grid of 156 as 13x12, could you then count them from left to right into smaller grids of 30 as 6x5, or top to bottom?