This project is a simple adapter between a salvaged ibm-style trackpoint (which speaks PS/2), through an adafruit trinket with an Attiny85 over to usb via vusb.
running with the micronucleous bootloader
the firmware code itself is pulled together from the v-usb hid-mouse example and the interrupt based ps/2 code from here
piggy backing components on modul variant A or variant B
piggy-back as 0805 on the trackpoint board
/----------------------------------------\
| |
| |
Vcc --||----+ SK8707 (?)
Vcc Vcc Vcc 2.2uF | +-------------------
___ ___ ___ ___ | |
| +---+ | | | +-----------|--------+ Data
+---+ | | | Attiny85 | | | | |
| | | _ +--+-----------------+ R R 1-10k pullups | +--------+ Reset
| 1.5k === ^ Red | | | | | | |
USB | | = | | | | | | 100k + Btn middle
+---------+ | | +-470R---+ B1 | | | PS/2 Data | | |
| 5V +--+ | | B0 +-----+---|------------------+ === + Btn right
| D- +------+---68R------+-----------+ B3 | | = |
| D+ +----------68R--+---|-----------+ B4 B2 +---------+---------------------------+ o--+ Btn left
| Gnd+--+ | | | | PS/2 Clock | / |
+---------+ | _ _ | | +------- o -+ Clock
| ^ ^ Z3.6 +--+ Reset | Vcc | |
=== | | | | | ___ +---+--+ Gnd
= === === o +---------+----------+ | | |
= = / | +--------|------+ Vcc
o === | |
| = === + NC
=== = |
= = = + NC
= = |
= Adafruit Trinket internal = +-------------------
=====================================================
Trackpoint:
https://www.reddit.com/r/MechanicalKeyboards/wiki/trackpoint/
https://electronics.stackexchange.com/questions/155662/old-ibm-trackpoint-pin-scheme
https://www.reddit.com/r/MechanicalKeyboards/wiki/trackpoint/
https://github.com/joric/jorne/wiki/Trackpoint
https://deskthority.net/wiki/TrackPoint_Hardware#2-piece_Trackpoint
https://github.com/qmk/qmk_firmware/tree/master/keyboards/handwired/trackpoint
https://github.com/alonswartz/trackpoint
SK8707 module
https://raw.githubusercontent.com/alonswartz/trackpoint/master/pinouts/ic-1-ptpm754dr.jpg
https://raw.githubusercontent.com/alonswartz/trackpoint/master/datasheets/tpm754.pdf
Vusb:
https://cdn-learn.adafruit.com/assets/assets/000/010/774/original/adafruit_products_trinket5.png?1378223478
https://codeandlife.com/2012/02/22/v-usb-with-attiny45-attiny85-without-a-crystal/
