The Display Breakout Board MAX7219CNG

Using an Arduino Duemilanove or Uno to control these will require a little more than chance. A common pin on an LED matrix is wired to control the cathode or anode of a row or column. As a result, the matrix may be controlled using only 16 pins as opposed to 64 distinct ones. To control an LED matrix, there is one more method that must be used, and that is to turn on one LED at a time. There are places where if you light up two LEDs, a third one might also light up when LEDs are wired in a matrix. Each LED is immediately turned on and off to prevent this.

I decided to utilize a Maxim IC named the MAX7219CNG. This will enable the matrix to address each individual LED.  These are available at Sparkfun Electronics. This is the data sheet. One 8x8 LED matrix was intended to be controlled by this IC. This project requires 6 of these ICs because we'll be using 6 matrices in it. This project's development will be made easier by a great library that was made for these. This IC and library takes care of lighting up which LEDs that you want to light up without worrying about turning them on and off quickly like I explained. This will allow us to easily create and display images and worry about the pong side of things and not about all the finer details of displaying the image.

Now the IC needs to be connected to each matrix using the correct circuit. I designed a simple breakout board for this IC. I am not an electrical engineer, but the schematic you see in the pictures is pretty much what I understood from this page . Not really that complicated. I made this in Eagle and have uploaded my schematic and board files for you. Basically there are headers for the communication pins and for the output pins that go to the matrix. There are 2 capacitors on the input power and a resistor that sets the current for the LEDs. I used a 1K resistor for my application which worked fine.

So once you have the files, you can order the PCBs (printed circuit boards) from a batch house, I use Seeedstudio  which will cost about $10 for 10 PCBs, or you can always create the circuit on a prototype board if you choose. You can see some images of my finished PCBs in the pictures.

You can order the parts needed to assemble the breakout boards from Digikey .

The parts needed are:

- 6 10uF electrolytic capacitors

- 6 0.1uF non-polarized capacitors

- 6 1K resistors

- 6 24 Pin IC sockets

- Optionally you can use headers instead of soldering wires directly to the boards. I did not.

Now solder these components on to the break out board. This is a pretty simple step. You just have to make sure you put the polarized electrolytic capacitor in correctly and line the notch in the IC socket up with the notch in the silkscreen of the PCB. See the pictures for the soldering step. When you are done soldering, you can insert the MAX7219CNG right now or wait until after you solder the matrix in place, which will be next, so you do not damage the IC in any way.

IRF7413       LM348N           LM2904          MAX693CWE            IRF640

LM124J      MAX1617AMEE      IS61C256AH-15J        INA114AP         LM324DR

LF398N        ICL7107CPL        LF356N         EPM3256ATC144-10       AD1981BJST

AD574AJD     BCM5208KPF      AMS1117-3.        FDS6912A         EPM3064ATC44-10N