Advice on a 8x8 RGB LED matrix

Hi All,

I have to build a 8x8 RGB LED matrix. For that reason I searched the web for instructions and background information. Unfortunately I haven’t found a resource were I could start with.

Therefore, could anyone give me an Advice or link were I can find informations or a tutorial on how to build such a 8x8 RGB matrix from scratch including all necessary components that i’ll have to buy? All I found so far were these 8x8x8 cubes or pre-composed Adafruits shields but I need to arrange the LED’s freely therefore something like this unfortunately doesen’t work for my needs.

Thank you…

I need to arrange the LED's freely therefore something like this unfortunately doesen't work for my needs.

So just buy the individual NeoPixels and solder them how you want. These new devices are just the job for an 8X8 matrix.

Building your own can be tricky. This is my project and essentially it is an 8X8 matrix, can you handle this amount of wiring? http://www.thebox.myzen.co.uk/Hardware/Hexome.html

Hey, thanks for your answer!

Do you mean these here: http://www.adafruit.com/products/1655 I'm afraid, the Smart NeoPixel are too expensive for me :-/

Btw: Really nice project you have there, well done! This reminds me a bit on what I try to do. It's a board-game which I do as a school project and in my case, I will have one button which should set randomly the color of each LED.

I'm afraid, the Smart NeoPixel are too expensive for me :-/

If you got 64 of them they would cost less than $30.00, that is not considered expensive in the electronics world.

What sort of budget do you have? You might struggle to get the LEDs alone at that price let alone the electronics to drive them.

Ah, I thought you mean these NeoPixel packs: https://www.adafruit.com/products/1260 They would cost $114 only for the LED's..

If I can do it with these I will certainly go with this product.

On my iPad now and I can't see links on the new forum. But that first link was just under $5.00 for ten.

Yes, these are the WS2812B 5050 RGB LED. I'll take them as soon as I find out how i can wire them up and control it with Arduino.

The thing is they are surface mount parts so they take a bit of skill with a scalpel to hack normal strip board so you can use them. Basically the trick is to cut the strip board along the length between the holes to turn the 0.1" pitch into 0.05" strips. Then you can solder them up.

Hm. I don't know if i'm understood you right. Considering these images of the LED's: http://www.adafruit.com/images/970x728/1655-00.jpg http://www.adafruit.com/images/970x728/1655-01.jpg

What / were do I have to cut?

Another question would be, if I need additional capacitors a.s.o to power all 64LED's up

What / were do I have to cut?

The tracks on the strip board you are going to use.

For a 6 pin LED you can cut the strip board like this.
And the picture shows the way the resistors are mounted.

However the new 4 pin LEDs look like they can just be bridged across 0.1" strips.

I need additional capacitors a.s.o to power all 64LED’s up

Yes of course, surface mount ones of 0.1 to 2uF per LED should suffice.

strip cuts.pdf (16.7 KB)

Ah, I see.. Thank you!

BTW: The advantage using this kind of LED's compared to normal LED is, that they include a IC right? I'm not sure but i assume that this element is used to reduce connections?

Do you might know a resource showing a wiring diagram of a possible circuit like this?

This page has them cheaper and has example code:- http://www.seeedstudio.com/depot/WS2812B-RGB-LED-with-Integrated-Driver-Chip-10-PCs-pack-p-1675.html

[u]Thank you for that link![/u]

For me the really crucial thing is which parts I need in addition to these LED's to end up with a functional circuit. I tried to find an article about these kinds of circuits how to setup / plan the circuit with all the needed parts (LED's, resistors, capacitors, a.s.o)

There are some resources i found but the most youtube videos only show the final result /or how to solder 8x8x8 cubes.

All you need are decoupling capacitors, one for each LED chip. You do not need any resistors or other components.

Good to know, thank you so much! Is there a difference between decoupling capacitors and "normal" capacitors? Or are they just called so because they prevent power issues?

s there a difference between decoupling capacitors and “normal” capacitors?

Moot point. Decoupling capacitors should always be ceramic (at leas the small ones ). What is a normal capacitor? There are many types and each type has it’s own strength and weakness.

Have a read of this:-

Okay, I have read some articles about capacitors. That was a good idea. :) I think i'm ready to make my orders. However, now there is one question left. I made a little wiring diagram showing how the wiring for the 64 LEDs should be. I just made 2 because i wanted to ask you first if this diagram seems right to you before i'll do the whole one.

Yes that looks fine. :)

Cool ;)

But i'm still having trouble finding the right capacitor model. I'm not sure if I really need a SMD cap. They seem to be really small and therefore not easy to solder without additional hardware. It might be easier to use a model with legs?

t might be easier to use a model with legs?

It will be but they are not as good.

I'm not sure if I really need a SMD cap. They seem to be really small and therefore not easy to solder without additional hardware

You just need a good pair of tweezers and a fine tipped soldering iron.

I use strip board for building my projects and a SMD cap fits nicely between the tracks. Note that these LEDs are also surface mount parts.