Wednesday 19 October 2016

pinout - 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


enter image description here enter image description here




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.


enter image description here



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



enter image description here




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


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