Path: utzoo!attcan!uunet!snorkelwacker!mintaka!streeter
From: streeter@theory.lcs.mit.edu (Kenneth B. Streeter)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Using a PC to monitor an external signal (How?)
Summary: Help Me!
Message-ID: <1990Jul4.215014.29212@mintaka.lcs.mit.edu>
Date: 4 Jul 90 21:50:14 GMT
Sender: news@mintaka.lcs.mit.edu
Reply-To: streeter@im.lcs.mit.edu (Kenneth B. Streeter)
Organization: Laboratory for Computer Science, MIT
Lines: 27


I would like to use an ibm pc to monitor an external signal.  The
signal in question is from a single digital wire.  The signal on the
wire is essentially a square wave, from 0V to 5V, with an irregular
period.  The input signal frequency would never be above about 150 Hz.
Essentially, what I want to do is simply count cycles.  (Rising edges
of the wave, actually.)  It would be nice to be able to count LOTS of
these pulses (for about 8 hours).

Basically, I'm looking for ideas on how to do this.  I've got a few
ideas, but would like to see something relatively simple.

For those of you that may be a little more interested in the
application, this is for installation in a car.  The square wave is
from a wheel sensor which basically gives a cycle every time the wheel
rotates.  The count is counting wheel revolutions, which can be used
to calculate distance, speed, etc.  (Thus, it would be essential to
have a laptop capable of doing this.)

Thanks for any ideas.


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Kenneth B. Streeter         | ARPA: streeter@im.lcs.mit.edu
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