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geekhack Projects => Making Stuff Together! => Topic started by: Didac on Fri, 28 December 2018, 06:06:56

Title: Connect a (thinkpad) trackpoint to an Arduino Pro Micro
Post by: Didac on Fri, 28 December 2018, 06:06:56

Hey geekhack,
This is my first post and my first project ever. I'm very new, so I'm sorry for my ignorance.
I want to build an Atreus keyboard (using an Arduino Pro Micro) with a trackpoint. The trackpoint I have is one salvaged from a thinkpad x220.
It is this one: https://imgur.com/a/nlhMTDe (https://imgur.com/a/nlhMTDe), https://imgur.com/a/qH0NEpW (https://imgur.com/a/qH0NEpW). I have one concern, do you think I've broken it when extracting it? As you can (barely) see, those four little connectors snapped as I got it out. Do you think those are re-soldable?
If it cannot be fixed, I could get another one from other second hand thinkpads, or maybe a trackpoint/joystick arduino unit. Do you know if any joystick-like arduino unit could be used for this purpose?
How should I connect and test the arduino pro micro and the trackpoint? I'm not asking for an exact detailed guide, I just want to know where to start researching.
Thanks in advance!

Title: Re: Connect a (thinkpad) trackpoint to an Arduino Pro Micro
Post by: Findecanor on Fri, 28 December 2018, 06:45:36

I think that maybe you could salvage that. It looks like you have only a broken lead, not a broken component. In the worst case, you would have to scrape off some solder mask off the top of a trace and solder onto that.

It looks like your trackpoint module is similar to the one in the ThinkPad R61 (https://deskthority.net/wiki/TrackPoint_Hardware#ThinkPad_R61_TrackPoint). It speaks PS/2, but the buttons are inputs (the switch's other end is ground).

Atreus uses the QMK (https://github.com/qmk/qmk_firmware) firmware. It has support for PS/2 mouse in (https://docs.qmk.fm/#/feature_ps2_mouse), intended for trackpoint mods such as this.
Compile with "avr-gcc" and then transfer the ".hex"-file to the Pro Micro with "avrdude" or WinAVR.

Here is a thread on programming the Pro Micro (https://deskthority.net/viewtopic.php?f=7&t=8448). I have used this script (https://deskthority.net/viewtopic.php?p=190315#p190315) from that thread specifically, under Linux with avrdude.

And welcome to Geekhack!

Title: Re: Connect a (thinkpad) trackpoint to an Arduino Pro Micro
Post by: Didac on Sat, 29 December 2018, 06:18:55

Thanks a lot for the insightful reply!
The first step I'll make is to test the trackpoint. Then I'll modify the atreus case (openscad) and have it 3d printed.