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How do I control an LED message board via USB? Answered

Hey, this is my first post so bere with me as I may be a bit all over the place.

I am trying to control an LED message board via usb.

It has a manual keyboard on the bottom that upon closer inspection has 8 wires on one side and 7 on the other.
By placing a wire between a wire on one side and a wire on the other a character is inputed.

So by using some sort of USB interface with at least 15 pins I think it must be possible to input to it via USB.

e.g. When A is pressed wires 8 and 15 should be connected in order to input A, for B wires 8 and 14 should be connected, ect.....

I am also getting my Rasberry Pi sonn and was thinking that the GPIO pins could do this but i'm not sure.

This website documents a similar project using the same display but via a different method: http://srimech.blogspot.co.uk/2003/04/led-message-board-hacking.html

Thanks for reading, please help!!!!



A 'Pi would do it, if you attach a serially addressed analogue matrix switch to its GPIO pins. If you need some part suggestions, just shout.


Thats sound best as plan on showing current user numbers of a website and using a Pi means I can leave it running without sacrificing a laptop.

How would I go about this?


Take a look at something like the MAX4587, which is a 4:1 mux switch - you'll need 14 of 'em !

Or. the ADG728 - you'd need 7 of them.

I hesitate to suggest the DG884, of which you would only need two, because they are parallel addressed, and I don't know how many external GPIO pads the PI exposes.


I here is the layout of the raspberry pi's gpio pins http://elinux.org/images/2/2a/GPIOs.png

I was also wondering if arduino uno would be capable of this?

It HAS SPI out on there - which makes this MUCH easier to go for the first two parts I suggested.


6 years ago

Sounds like a USB micro processor whose output lines controls a small matrix of mosfet LED 6 pin IC opto isolators.

Parallax inc sells a USB stick uP with a patch area and simple free software that could do this for you.