pulse width meter project

[steve ravet]

I've completed a simple pulse width meter project.  The goal was to
learn how to use Protel schematic capture and board layout.  I've got a
lot to learn still but the meter works.  On the diy-efi WWW page is a
Protel schematic, a jpg of the same (thanks for the suggestions), and
the PIC assembly source.

It's very simple, the PIC measures the pulsewidth and displays to an LCD
module.  It also calculates duty cycle and displays that.  It works well
on the bench, measuring down to .2ms with an accuracy of .1ms, up to
30ms.  I tried it on my TBI truck but couldn't get a good connection at
the injector.  Plus if it got too close to the engine it kept
resetting...  It's wire wrapped now I'm sure a board and a box would fix
that problem.

The code is "just now working" and could be a lot better.  It's a 2 line
display and the schematic supports measuring 2 pulsewidths at the same
time but the code only does 1 for now.  I'd like some comments,
especially on how I could make it  more rugged.  The inputs are
opto-isolated but the power supply is just a 7805.

It's officially released under the GNU license.  The design is freely
available but if it's used commercially any improvements must also be
freely available.

--steve

-- 
Steve Ravet
steve.ravet at arm.com
ARM,Inc.
www.arm.com
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