Hello,
I'm a programmer and want to step into the world of electronics and microcontrolers. So I bought myself an arduino mega and two led matrices: first 8x8 single color, second 8x8 RGB. Both are common anode matrices.
I have driven the first one by multiplexing: took the anodes as rows and the cathodes as columns. I set one row to high and the cols that I want to light to low. then switched to another row... so far so good.
After I played around with it, I wanted to drive the rgb matrix. I left the code and first drove the blue color. it worked as before. Then i wired the other colors up, where I start facing problems. I first realized that in this way I could only possibly get 7 colors by mixing (r, g, b, rg, rb, gb, rgb). The second issue I face iwas: if I power the red led, the others don't light up, as if the red is stealing current. I googled a bit and found out, that i could get different colors by using pwm, using
this tutorial, but I don't quite get it. The code in page 5 of the how to it uses pwm for the cathode part. Mustn't it be negative pwm values as it is the cathode part? How am I supposed to apply this to my matrix? Using this method I must use 24 pwm pins which I don't have. Or can I use only the anodes as pwm pins? But then again I cannot use different color values for each of my leds in a row. Or am I supposed to multiplex every single led using 64 cycles for one image, instead of only 8? Do I get the concept of multiplexing wrong somehow? what am I supposed to do? Any hint is appreciated
