QMK as input device

[ame]

I posted this over at the X-Plane forum, but it is useful for any sim. I haven't had any response, but I think it is worthy of discussion.

Is anyone else playing with QMK? It's been around for a while, but I just discovered it.

QMK (Quantum Mechanical Keyboard) is an open source project for building keyboard controllers. An Arduino Pro Micro (or other microcontroller) is programmed to appear as a USB keyboard when plugged in to a PC. The firmware in the micro scans the physical keyboard switches and sends keystrokes to the PC.

But wait, there's more! As well as behaving like a keyboard it can also behave like a mouse and send mouse movements or mouse clicks when a key is pressed. Or a rotary encoder can be attached which will send keypresses for each click of the encoder. Or a pot can be connected, which will send joystick data to the PC.

It is essentially a versatile and highly configurable input device. And since an Arduino Pro Micro costs less than US$5, it's cheap too.

Furthermore it can be programmed to send several keystrokes in response to a single keypress, and other useful features.

I have used it to make an FMC keyboard (see my other posts). The keyboard is just a PCB with a matrix of pushbutton switches (and a rectangular hole for a 5" VGA display module). I have an Arduino Pro Micro running QMK which I have configured with the A-Z keys generating 'a'-'z', 0-9 generating '0'-'9', the soft keys either side of the display generating 'F1'-'F12', EXEC generating 'Enter' and so on. When plugged in it looks like a USB keyboard, so no drivers are needed. Any key can generate any keycode, which you can configure to your liking.

I've done a little bit of Googling, and there doesn't seem to be many sim builders using it, but it could be that sim builders haven't discovered it yet. As I said, I have just tried it myself for a simple keyboard and it works. I think a lot of its features would be useful for flight simulators. At $5 per micro you could build two or three keypads with a few keys each, for custom functions. Or incorporate a QMK micro into a simple instrument or panel.

For more reading: https://qmk.fm/

Having used it once (it worked) I am clearly now an expert and happy to answer/deflect any questions.