Easy Button Musical Interface

Step 2 Map the USB Keyboard

As shown in Dave Merrill's Key-Ped project, a cheap USB keyboard can be taken apart to serve as the input to the PC. This hack takes advantage of the fact that two keyboards can be used at the same time for input (so far this was true in Windows XP and OS X). When dissasembled, the keyboard has two main parts: a membrane of circuits that form a matrix mapping to keys, and a circuit board that scans the membrane switches for activity.

I found the numbers 0 to 9 and traced them to where they were connected to the circuit board. Each number/character is mapped to two inputs on the circuit board, so when that combination is switched, the keyboard sends the corresponding character to the PC.

Comments

[Unclegummers]

I did the same thing with the same keyboard! I scanned the layers and used photoshop to track the buttons. I was trying to map it to send it to an older keyboard, but it never worked out because the keys were mapped completely different :/ . Nice project btw.

[madcow3417]

Mapping the keyboard can be done easily with a digital camera and a paint program. Just take a picture of both pieces with a contrasting background. Open it in a pain program of some kind, I use Graphic Converter on my mac. Use the fill tool to fill in the trace for the particular key you want to map. Because they don't cross each other it will fill in just that one all the way back to the circuit board. Use a different fill color for any other keys you want to follow back.

[bifter]

This is genius! I've used this USB keyboard hack to build a controller for Serato Scratch. However, I need a lot of buttons and was thinking how much of a headache it's gonna be to trace back all the keys. Thanks :)