Hello all.

I'm using a 16F84 to sample the tach output from a late model Honda.  This
output is supposed to be a square wave with 2 pulses per revolution of the
engine.  When I count the pulses, the frequency I'm getting is twice what I
would expect.  I've noticed a similar result when I measure the output with
a Fluke 87.  The frequency is twice what I expect.  Only if I put the meter
on the 400V setting are the frequency measurements what I expect.

I don't have a scope so I can't really see what I'm dealing with here.  The
signal is supposed to go between 0v and 12v but there must be some ringing
or something.  What advice would you have for sampling this signal
accurately?

Currently, the signal is just coming in (via 4.7k resistor) to the RA4 pin
where I have it hooked in to TMR0.  RA4 is Schmitt triggered I believe.

~j