I've been staring at Eagle for hours now trying to figure out how to layout a board with 90 LEDs in 5 rows of 18 charlieplexed (controlled by 10 pins).
Does anyone have schematics for something like this or any tips on how to multiplex so many LEDs on one side of a PCB?
You're not going to be able to do a single sided layout without lots of wire links added. With only ten pins wired straight to the display you will only be able to light one LED at a time which will allow a duty cycle of 1/90--very low if you're trying to display an image with any more than a handful of LEDs on at a given time. The common method is to use shift registers to drive columns and a demultiplexer or individual pins to drive rows (via darlington or FET or somesuch to provide sufficient current). That way you can feed an arbitrary amount of column data into the shift registers with 2-3 pins and display it all at once when you activate a row. You can control your matrix with as few as five pins with this method.
yeah, i figured there will be wire links. i'm looking to minimize how many there are and simplify the layout as much as possible.
I know there are easier ways of controlling this many LEDs. this project is more about the method than the the task.