I am multiplexing a 5 column and 7 rows dot matrix. I connected like how this site connect. Direct connection http://arduino.cc/playground/Main/DirectDriveLEDMatrix . However i only uses 12pins. And for the code http://hanez.org/arduino-ta07-11-5x7-dot-matrix-display.html i use exactly the same. Display do come out, but it make no sense to me - Dont look like a alphabet, just random jumping . BTW i'm using a common cathode 5x7 dot matrix. Maybe there is some problem with that?

That tutorial is bad because there is no current limiting resistors on the LEDs, this could destroy your arduino. Do you have some in? If so what value and where? http://www.thebox.myzen.co.uk/Tutorial/LEDs.html

i'm using a common cathode 5x7 dot matrix.

A matrix is common anode or common cathode depending on the way round you look at it.

Display do come out, but it make no sense to me

So set the code so that just one LED is to be on in a known place and see if it comes on in the place you expect it.

There is a tutorial for controlling two 5x7 dot matrix LEDs at LucidTronix: http://lucidtronix.com/tutorials/18. They use current-limiting resistors, and shift registers so it only take three signal wires… They have an Arduino library you can download that can take text, or set individual pixels.

Since this thread was resurrected I am going to mention that Maxim has a part that does specifically what the original poster asked for, it controls 1-4 5x7 matricies. Who would have thunk it?


Maxim has a bit of a premium on this chip but you can always ask for a sample.