Electronic – old ibm trackpoint pin scheme


I have a trackpoint from a thinkpad keyboard with a trackpoint mounting a PTPM754DR microcontroller, what I'm trying to do is to find the usage of various pin on the trackpoint board and connect them to a teensy 2.0 that already controls a keyboard (I'm using this firmware https://github.com/tmk/tmk_keyboard), what I've found on various sites and forums like geekhack are info from other trackpoints with a different pinout, I say so because I've traced at least the mouse buttons and saw the vcc and ground that have bigger traces than the others, how can I find the purpose of other pins? I cannot connect that keyboard back to a laptop.

Here is some images of the trackpoint and what I was able, probably, to trace

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Best Answer

According to this post on the geekhack forum:

R61 trackpoint pinout (with PTPM754DR) « Reply #20 on: Wed, 23 January 2013, 08:04:09 »

  1. DATA
  2. RST
  3. BTN1
  4. BTN2
  5. BTN3
  6. CLOCK
  7. GND
  8. VCC

When connecting to PS/2 interface, DATA and CLK should be pulled up to vcc using 4k7 resistor, RST to GND using 100k resistor and RST to vcc using 2.2uF capacitor.

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Notice the boards look identical. Also this other post and another:

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That last post has everything you need for using your trackpoint on the TMK firmware too.