8 May
2004
8 May
'04
9:06 a.m.
On Sat, 8 May 2004, der Mouse wrote:
Most likely the relative signal levels of the 2 closest wires to the puck are
measured and the position is then interpolated...
Peter Wallace
Oh, it's a
Kriz tablet (after Stan Kriz at 3 rivers).
I have never fully understood how they work
either. The 'wires' in
the PCB carry electrical currents, and are sequenced in some way by
the microcontroller. The puck/pen contains a pickup coil, the output
of which is amplified and fed back to the microcontroller.
[...]
And the resolution is _much_ higher than the
spacing between the
'wires'.
Much. The manual documents resolution settings as high as 20 counts
per mm; experimenting with it, I find it actually includes settings
that appear to attempt 1000 lines/inch and 1000 lines/mm, based on
dividing full-scale counts by pad size (in-my-head estimates; I could
be out by a factor of two or so). Of course, I doubt it's accurate to
anything like ±1 count at those settings. :-)