what interface is this?

[petanque]

hi, I have an old wireless keyboard with trackball mouse and without a receiver, that I would like to revive with Arduino but I don't see which interface the mouse is using, I hope someone can help me on the right path.

Here is a picture of the module.

So far I know that
Green is VCC
Blue and White are GND

But what about
Black - CLR? on pcb goes through 10k resistor before original chip
Red - PD? on pcb goes through 10k resistor before original chip
Yellow - SD? on pcb goes through 10k resistor before original chip

I hope someone has an idea, the 10k resistors are not pullup or pulldown as I first thought.

[MorganS]

Trace it back to the encoders under the trackball. Use the Arduino to read the encoders directly.

If it is an optical trackball (maybe with a dot pattern on the ball) it may be too difficult to re-engineer.