9x9 LED matrix

Hi, I made a 9x9 LED matrix as a project for home (I have found a 8x8 instructable https://www.instructables.com/id/Charlieplexed-Arduino-8x8-LED-Grid-Display-Shield-/)
but I wondered if it was possible to do it with a 9x9 matrix aswell?

Yes, it is possible, but very inconvenient!

That article illustrates everything that we on the forums here find detestable about "instructables". For example "In the software I gave them a value of 100 Ohm, but in reality, 10 Ohm or even no resistor is preferred. This is because each LED will flash only very shortly, so it isn’t at much risk for burning up."

The resistors are also shown wired incorrectly. I haven't looked at the code - I just could not stand to!

If you want an 8 by 8 matrix (and I cannot imagine why you want a 9 by 9 but ...), just purchase one - with its MAX7219 driver module - on eBay. If you want to wire your own matrix, well, just buy two or three of these kits:

Or these ones

which used to be more expensive but are now actually cheaper and more useful if you wish to stack matrix arrays. In fact, if you want 9 by 9, just stack four of these and you can have even more!

The point is that you do not install the matrix arrays from the kits themselves - or their socket pins, but just solder to the positions on the PCB and you have a durable and reliable assembly to drive your own matrix arrays.

Why did I say two or three? Well, you can fully assemble the first one as the matrix with which it comes and practice programming it. Then the second one for your current project and the third one - for the next! :grinning:

Considering the cost, it makes no sense to just buy one!

The fact I was making a 9x9 charlieplexed was just because i had way to many LEDs laying around still. Wired it based on a diagram I made and used the program as a reference. I will definitely buy those matrix kits aswell but was a experimentinf aswell with just LEDs (also for practicing and a 8x8 matrix was just copying so I went with a 9x9). It doesnt have to be something similar to the instructable. Only wanted to know if theres a sample for a charlieplexed 9x9 program so I can try it out and learn more from it