Hey Tony,

Are you expecting to field calibrate your speedo? I need to on mine - which
is another reason why I was considering a pulse counting routine. If I go
with a time-based period measurement, having someone go through a measured
mile is a problem. What I think I'll do is have a pulse counting function if
the calibration bit is set. Then push/drive/waltz a measured distance. That
pulse count should be able to used for calculating a calibration constant.
>From there I have a count to distance ratio that should help in getting a
count to time ratio. In theory, of course, if period measurement is the same
as a falling edge to falling edge count.

So it 1 mile = 23,000 pulses, I know to increment my odometer every 2,300
pulses (.1 resolution).
If my time period is 2ms between pulses then I get 500 pulses per second or
1,800,000 pulses per hour.
1,800,000/23,000 = 78.3mph

Ooo. Got to think about this...

-DO