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Topic: 8x8x8 multiplexed LED cube with an Arduino Mega 2560 (Read 41 times) previous topic - next topic

Nick Gammon

CrossRoads, doesn't your circuit require 16 wires per 64 LEDs? So the number of wires in the cube is the same as using the MAX7219? Or have I misread it?

The only way I can think of reducing the required number of wires to less than 16 is to use Charliplexing:

http://en.wikipedia.org/wiki/Charlieplexing

However that is quite complex. Also you still need 9 wires to control 64 LEDs (only a small saving).

Quote
For n pins, you can have up to n(n-1) LEDs in the matrix. Any LED can be lit by applying 5 V and 0 V to its corresponding pins and setting all of the other pins connected to the matrix to input mode.


CrossRoads

I think you are misreading the partial schematic.
Each common anode layer needs 1 wire.
The common cathodes need 64 wires, 1 per column, usually soldered to the PCB that makes the base of the cube.
72 wires total.
Vs  8 x 16 wires = 128, and connectivity not built into the array either. See the video that was posted in Reply #21.

Wish I had way more hours in a day to build one of these up.
I'd go for 9x9, have read having the center LED to pivot things around makes it look neater.
My 12-shift register board could drive it, be a bit of a software PITA spreading 81 bits + 9 anode control bits across 12 8-bit registers (96 bits).
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Un4Seen

CrossRoads, thanks again! :)
Yeah, I guess I was making too big of a fuss about the software multiplexing, it's not the end of the world after all :)

One last "dumb" question: You mentioned some pull-up resistors which should be 220 Ohm. Which one are those in the diagram and what is their role?

I think I'm going to create my cube based on this diagram and based on your explanations. But I'll start with a 5x5x5 one. It's just too complex to aim for the big rabbit from start...

Un4Seen

I looked for TPIC6B595 on eBay and found TPIC6B595N only. I guess it's the same...

CrossRoads

The pullups go on the Gate of the MOSFET (or, the Base of the PNP, as currently drawn).

Start with 5x5, leave room to expand it to 8x8, need to use whole bytes anyway...

TPIC6B595N, N is the package type.

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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