-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Paul B. Webster VK2BZC
Sent: Friday, March 31, 2000 10:19 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: pic16f84 & speed sensing


Mark Jenkins wrote:

> I am in need of some advice regarding the possibility of using a
> pic16f84 or any other kind of pic to sense the speed of two seperate
> wheels.  What I would like to do is to be able to turn a led on if the
> speed of one wheel increases to a speed of say for example 10% over
> the other.

  Sounds entirely practical.  May we assume you have optical "choppers"
on each wheel which have approximately equal mark and space, and
anywhere between one and 64 "chops" per revolution?

  Should be no trouble.  I'm too tired now, going to bed, but may have
an algorithm figured in the morning (unless everyone else gets there
first).
--
  Cheers,
        Paul B.

thanks for your reply paul i was hoping to use a hall effect sensor because
of the the ease of setting up this type of system with 4 magnets set 90 degs
apart on each wheel, i imagine this would make the software harder to write
and may require additional hardware so may not be practical or possible,
what do you think?