Dario, would you or Andrew care to add your mouse controllers
to the PIClist pages ? I did so for the interface part of a project
and have had quite a bit of (grateful) feedback over the years

http://www.piclist.com/techref/microchip/emouse2.htm

It does include left-click BTW, despite the title

Carl,

> The PC mice use a slotted wheel and a pair of photo sensors for
> each of the 2 directions of travel. Everything is relative motion (fore/
>back) and speed

Fewer and fewer users have ball mice now, but the principle is
the same. Converting sensor information to quadrature and speed
for the data stream. Most mice probably use a low-end PIC or
other OTS micro

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