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Topic: 5x5x5 LED cube help (Read 6 times) previous topic - next topic

Hippynerd

Cool, thanks for the explanation, I had missed the third group of pins, now i see 3 and understand that the other 2 would go with the last 2 rows.

suicidalacorn


"wouldnt turning on group 1 section 1 turn on that whole section? not individual LEDs?"
Only if the anodes were driven high for all LEDs. Otherwise, just the LEDs with High anodes turn on.

The idea is you enable 1 group of 5 LEDs at a time, a 5x5x5 cube would have 25 groups to cycle thru. 4% duty cycle.
Driving each group for 1667microseconds would yield a 24 Hz refresh rate - leaving over 25,000 cyckes in between writes to do other stuff.
I would imagine a loop within a loop to cycle thru the groups & layers, reading from a 25-byte array (upper 3 bits ignored) to send out a new byte every 1667uS. 2nd array of 5 keeps track of group enable pins, 3rd array of 5 keeps track of layer enable pins.
There are 5 anode drive pins, 5 group select pins, 5 layer select pinsl, so the whole cube is multiplexe with just 15 pins, directly controllable by a single '328P chip with no extra shift registers. Just 15 resistors and 20 transistors.
I didn't make one myself, just helped the original requestor with a design that could be done.

oh ok. that makes more sense. i thought you were saying to have constant current driving the anodes at all times. so you would just have transistors to control the anodes (or an LED driver like you posted earlier)?

suicidalacorn

ok, so for driving the LEDs i plan on doing what is described in this video (or something similiar with the ideas recommended by you guys). this is what i was trying to describe before. but i will use a pnp transistor where he uses a MOSFET (because i had a hard time finding those MOSFETS and transistors are much cheaper). skip to about 32:30 in the video to see what im talking about. https://www.youtube.com/watch?v=wVYXAR1GWxU

CrossRoads

You can drive the anode with 5 arduino pins.  PNP transistors are not needed.
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.

suicidalacorn


You can drive the anode with 5 arduino pins.  PNP transistors are not needed.

i am now confused. wouldnt that draw too many amps from the arduino? if i have all the anodes of each layer connected and i have 25 LEDs per layer, that would be 500ma per pin from the arduino to power it. am i misunderstanding something?

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