8x8 Bicolor LED Matrix with MAX7219

Hello everyone,

I’m following the circuit below to hook up my 8x8 bicolor LED matrix. So far, I am certain that I hooked up the matrix correctly but I’m not sure if I’m using the right resistor.

Right now, the LED will light up and only display the pattern below, if I try to upload any other patterns it will not change. Also the LEDs which are supposed to be red are showing up as orange at the moment. I’m using a 10uF and .1uF capacitor. I’m currently using a 33k ohm resistor to connect pin 18 to 5V power. (this a guess since I don’t know the forward voltage or amplitude of the matrix. I’m using an LED matrix from this site: https://www.creatroninc.com/product/8x8-led-matrix-20mm/).

Any assistance would be much appreciated!

The MAX7219 can not drive a bi-colour matrix there are not enough outputs to do that.

Also the LEDs which are supposed to be red are showing up as orange at the moment.

That means the red and green LEDs are both being lit up.

Have you got a data sheet for the matrix as the pin numbers don't mean much without one.

Ok that is my oversight. I was hoping that a bicolor would still work with the max7219. Unfortunately I can't find the datasheet for it, most bicolor matrices only have 2 rows of pins on either sides. This one has 2 rows on one side and 1 on the other. I will ask for the datasheet and post it here once I have it.

Thanks for the reply!