500 Leds matrix & long distance


I want to build a big led matrix, using around 500 leds, and 8 max7219.
Each led would be at 1 meter from the other.

I'm wondering if the distance is a problem.
I know that the distance between each max7219 can be a problem, but what about the leds ?

Thank you !!!


Yes it will be a problem. You will need to have good wiring and good decoupling with maybe a touch of decoupling on the LED signal lines. To do this project you will need an oscilloscope to make sure you are not getting into any trouble with the signals.

Something similar here, not 1m between LEDs, but still huge:

Thank you for your answers.
Florinc, thank you for the link!

For the decoupling question:
In the playgroung, there is this schematic with C1 and C2, which I assume to be decoupling capacitors:

GRumpy_Mike, you say that these capacitors won't be enough, and maybe I should add some on the led lines ?

For the wiring, I wanted to use stranded hook-up wire, 24 AWG. Not a good idea ?

Yes those two capacitors are decoupling. But it is not just a matter of slapping capacitors on and that's job done, although it is better than nothing. As you are so new to the concept of decoupling then read:-

However layout is critical, and you can't always tell ahead of time where the critical areas will be. It is not a simple matter of using this or that gauge of wire. These things are complex and take experience.

You asked:-

I'm wondering if the distance is a problem.

and I said yes it will be a problem. Electronics, like many other things, doesn't scale up easily. That is why I said you need an oscilloscope and the knowledge to use it for this project.

I think that using shielded cables or twisted pairs should avoid picking up interference from the environment (which may be the main cause of problems due to distance). Computer networking works pretty reliably at much higher frequencies and over much longer distances.

Computer networking works pretty reliably at much higher frequencies and over much longer distances.

Yes but the hardware is designed to do that high speed long distance communication. Normal logic chips are not. You can't just say because one is possible so is the other. For example networks use differential signaling not single ended.

Thank you for all those informations.
I'm going to buy some stuff, and make some tests, and I will tell you the results !

A log distance led project:


So you want to do a matrix that uses 500 LEDs that are each 1 meter from each other?

Are you absolutely sure about that? Because that structure will be larger than 22*22 meters, assuming it's a square... and then you'll need more than 1 LED for it to be visible as a matrix at all.

That SyynLabs project did not use smart LEDs at long communication distances. Instead, it used clusters of Arduinos attached to chains of OctoBrite DEFILIPPI LED controllers, and then long wires running from the controller modules to the LEDs in foam balls. Long distance communication took place between the Arduinos and control computer. You could use Ethernet or RS485/DMX.

The actual wires leading to LEDs are much less susceptible to noise issues over long distance. You would only need to worry about possible voltage drop or inductance over very long wires.

Thank you for answers.
I'm waiting for some stuff ordered on internet.
I will come back in 1 month to tell the results of my firsts tests.

So, I've done my firsts tests.
I've received my max7219 (from China ... 10 pcs for 10 euros ...), and made a first matrix:
88 leds, 1 meter between each led, 14 meters between the max7219 and the first led. (it's the furthest matrix of the final projet: 8 matrix of 88 leds)

It seems to work very well. Now I've to test with 7 more matrix ...

One strange thing:
Normally, my matrix should be like this:

00 01 .............07

Mine is like this:

07 77 67............17
00 70..................10

I don't understand why ...
But it works also like this !!!

I don't understand why

It is rotated through 90 degrees, either from the way you have wired it or simply the way you have it mounted.