Push-Up - GPIO buttons for USB

Every now and then one would like to have some distinct buttons on a server, pc, raspberry pi or whatever. A keyboard would be too big, not rigid enough or does just not fit the purpose. So I tried to scrap an ordinary USB keyboard. A mechanically dysfunctional keyboard is something to get easily hold of and the keyboard controller is just fine in most cases. Here we go...

Here we have one of those flexible keyboards. I really don't like typing on them and since I don't run a bar or take my laptop with me when scuba diving I've no use for it. So this is the one.

Disassembling is easy. We just need the controller on the right side.

The controller board.

Now there is some reverse engineering to do. We need to know which key connects which ports on the controller board when pressed.

This shows which key connects to which ports.

Test: connecting the both left most contacts produces endless amounts of 'q'.

Shopping cases and buttons: which case should it be?

The grey case looks more "technical".

Milling the holes for the buttons.

Prepared case.

Buttons mounted.

Backside of the mounted buttons.

Button wiring.

Controller wiring.

Last glimpse inside.

Ready to go.

Best served with raspberry pi.

what else?

You might like to use a triple (or higher) contact button. So you could build the (in-) famous CTRL-ALT-DEL device.
You might like to use a dual (or higher) contact button to build an external '@' key to be used with digital fruit.
Using libusb it's possible to keep the button's input apart from the usual keyboard input and get the events to trigger some random action. At least this works on Linux ;-)