I'm just thinking about re-using things.
Reverse engineering for PS2 mouse (additional photos, & links to FCC web site with schematic diagrams (.pdf)).
/* There are additional photos to the article located here. */
A PS2 mouse (Logitech M-S48a) has a single controller that manages everything.
A sensor that detects the movement of the mouse wheel.
Absolutely exactly the same sensor recognizes the movement of the ball. The difference is only in light sources.
All sensors have a single marking (EL + E9z01), but this does not help to find datasheet on it.
And one more sensor, from another mouse. Same, PhotoIC 'Rambo5', LT. 'H70BE' or 'H7OBE' on the back - most likely, a "man. date code".
The following photos will be useful if you want to recalculate the number of holes in the encoder discs. For the mouse wheel sensor.
And for the sensor, which recounts the speed and travel direction of the ball.
In general, this is all that is necessary for me, at the moment.
Schematic diagrams from FCC web-site (links):
*** And if you find inaccuracies, or have something to add, then my address is lower.