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[Reply #15 on:]

"controlling 5 LEDs at a time, and doing that in a loop of 5 that is inside another loop of 5, and you have controlled all 125 LEDs."
I have posted that before. Doubt I could find it with a forum search - I can post it again when I get home.

[Reply #16 on:]

Cool! If you find it, please send it to me, or post it, im mostly just curious, sometimes i do build samples, just to see it work, just because I think thats neat.

[Reply #17 on:]

I know where it is, I had it open to maybe copy part for what I had posted earlier in this thread.
Be home in an hour or so, will post it then.

[Reply #18 on:]

I know where it is, I had it open to maybe copy part for what I had posted earlier in this thread.
Be home in an hour or so, will post it then.

awesome! thanks!

[Reply #19 on:]

Here it is.
I only did 3 of 5 rows, the other 2 are connected up the same.

[Reply #20 on:]

Here it is.
I only did 3 of 5 rows, the other 2 are connected up the same.

i do not really understand that. i understand the logic and how it works, but not how you would implement it in the cube. it looks like it would control each colomns cathode, and then somehow have a second transistor to control the cathode a second time, but it would be based on each layer. i just do not know how you would wire that. maybe i am understanding it wrong. sorry for my questions, i am just trying to learn. as previously stated, i am a noob. i have been messing with electronics since i was a baby, but never anything like this. thanks so much for your help!

[Reply #21 on:]

The first 3 layers are shown. Columns are the anodes.
Each layer is made of 5 groups of 5 common cathodes  - one group of one layer is turned on at a time.

[Reply #22 on:]

The first 3 layers are shown. Columns are the anodes.
Each layer is made of 5 groups of 5 common cathodes  - one group of one layer is turned on at a time.

but wouldnt turning on group 1 section 1 turn on that whole section? not individual LEDs?

[Reply #23 on:]

I think I was imagining something different than that, but that is pretty interesting too.

It looks to me like that does all rows at the same time, but does one section at a time, meaning a 20% duty cycle.

I was thinking something that would do one section on one row, then sequence through each section, until it gets to the last section, then shifts to the second rows first section, sequences through each of that rows sections, and moves on to the next row, until it completes each section in each row one time. I think that would be a 4% duty cycle.

Actually building one of those seems quite challenging, but I could be wrong.

suicidalacorn, I think that anode pin controls the individual led, in each section of 5 LEDs, if I understand your question.

[Reply #24 on:]

"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.

[Reply #25 on:]

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.

[Reply #26 on:]

"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)?

[Reply #27 on:]

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

[Reply #28 on:]

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

[Reply #29 on:]

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?