Hey this is a pretty easy question I just want to make sure before I wire it up and find out that for some reason it doesn't work. I'm making a simple 16 x 6 LED matrix with a couple of HC595 shift registers and multiplexing and I want to do some simple global PWM for it. If I attach one of the PWM pins to the output enable on those shift registers it will control brightness for the whole thing right? I know that I can do some really fancy things with software and timer code (which totally loses me) but I want to keep it simple and just have on and off. Thanks for the help
Yes. Brightness will be from 1/255 to 255/255, switchin ~490 Hz.
Sweet thanks thats what I wanted to know
You might have to do something clever to synchronize your matrix refresh with the PWM. Otherwise you will get beats between the two frequencies and it will look like the display has gone mad. However if the PWM is very much faster than the refresh rate then there should be no visible problem.
Thats a good point. I'll just put it to a PWM pin and see what happens. I can see how I might get different brightness level rows that move up or down slowly because of the PWM interaction. Worst case I can always just write that pin low and not mess with it
I can see how I might get different brightness level rows that move up or down slowly because of the PWM interaction.
You will only get that when the two rates are almost exactly a multiple of each other. That would be rare. More likely this results in what you would see as random flashing of the display.