QMK + ChibiOS + Trackpoint?


26 May 2019, 03:42

Hi all. I'm trying to get the trackpoint to work on my Thinkpad/Teensy 3.2 keyboard.

https://github.com/eyemyth/qmk_firmware ... enovo_t420

I haven't had much luck finding code that will work with QMK and ChibiOS for this purpose. I'd really appreciate any help you might have to offer.

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31 May 2019, 16:04

Sup dude, I haven't personally touched much on QMK and I know very little about ChibiOS, but if you can't find any relevant code you may have to figure out what lines the trackpoint uses and figure out what kind of signal it produces and translate it to a USB mouse. It probably uses a XY coordinate through 2 different lines respectively (best case scenario) though I'm just speculating so I don't actually know if its going to be that simple. You may have to figure out what lines those are first, though its possible someone has already found that out. Also for that to work afaik you need to add a mouse descriptor alongside your keyboard descriptor for the USB driver, which is very much possible but again idk how to do that with QMK, it could be that QMK already has something like that added in the USB driver.


01 Jun 2019, 01:58

Most trackpoint modules speak the PS/2 mouse protocol. TMK (and probably also QMK) has PS/2 mouse input support for AVR: with options for three different types of pins (if I remember correctly): UART and not.

If I were you, I would:
* Try to find a ChibiOS PS/2 mouse input driver, and if that fails:
* See if I could port TMK/QMK's PS/2 mouse input from AVR to ChibiOS/Freescale,

PS/2 is a device-controlled protocol: the "mouse" sends bytes on a simple data/clock serial line with start and stop bits (ten bits per byte).
I'd think that the Freescale MPU should have some compatible UART that would trigger an interrupt each time you have received a full byte from the trackpoint.

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