Author Topic: Connect a (thinkpad) trackpoint to an Arduino Pro Micro  (Read 849 times)

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Offline Didac

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Connect a (thinkpad) trackpoint to an Arduino Pro Micro
« 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/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!

Online Findecanor

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Re: Connect a (thinkpad) trackpoint to an Arduino Pro Micro
« Reply #1 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. It speaks PS/2, but the buttons are inputs (the switch's other end is ground).

Atreus uses the QMK firmware. It has support for PS/2 mouse in, 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. I have used this script from that thread specifically, under Linux with avrdude.

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Offline Didac

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Re: Connect a (thinkpad) trackpoint to an Arduino Pro Micro
« Reply #2 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.