Homebrew PCBs

On Mon, 30 Aug 2004 21:23:23 -0700 (PDT), ron amundson  
<mnphysicist@...> wrote:

>> > All one would need to do, is add some type of
>> position encoding to the mouse
>> > wheel, and one would be all set.
>>
>> Nah,  that'll all be handled in the software.  As
>> would the resolution,  for
>> that matter.
>
> Could you elaborate as to how..... Especially in a
> power down condition where upon one could loose track.
> I take it, there is some trick, as many devices, use
> relative rather than absolute positioning. WIthout a
> home position to index off of, it would seem one could
> loose the position of the pointer if it were turned
> and power was off.... Or is it interrupt driven such
> that the micro stays alive and wakes up should the
> shaft be turned???
>
> Ron
>

Usually "thumbwheel" encoders are only used incremental.
like up/down buttons. the absolute positions are stored in memory if needed
and often the thumbwheel is used to adjust many values, selected by  
buttons.

ST