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Measuring PWM /w input capture ECT

Started by jeffguilfoil December 26, 2002
What your suggesting would certainly seem to work. I'm a real newbie
with this stuff, so the reason I selected the method I'm using is
because I knew it to exist. :) I definately appreciate the concern.

I picked my current method because I want to be able to measure the
RPM ASAP. As a result of the RPM I'm going to alter the A/F ratio by
modifying the air flow meter signal. I'm not certain where the
tolerance levels lie, so rather than tempt fate I'm hoping to make
the operation as fast as possible.

I'll take a read of your link and see what I find. I didn't find diy-
efi that usefull before, maybe I missed something.

Thanks,
Jeff --- In , Andrei Chichak <acpmiedm@t...> wrote:
> I'm just wondering why you would do this type of timing rather than
doing
> an RPM count and calculate the times?
>
> If you are trying to determine the positions to synchronize
injection or
> ignition pulses, I'm not sure you are on the right track at all.
There are
> quite a few web sites around dealing with injection/ignition that
you might
> want to look at. Start at www.diy-efi.org. Motorola, I seem to
remember,
> has an app note on doing injection using their modular counter time
module
> (CTM) if my memory is not failing. THere has been articles
published by
> Circuit Cellar www.circuitcellar.com that have these systems well
> described, and Al Lipper has a couple of systems written up that
use 8051s.
>
> Andrei
>
> At 02:24 AM 1/18/2003 +0000, you wrote:
> >I appologize for the late reply.
> >
> >I'm measuring the time between when the pulse goes high. ie. |-|_|
> >That time changes when the RPM changed on the CAS. Also, the peak
|-
> >| and vally |_| time changes perportionally with RPM. I took an
> >Oscilloscope to a CAS to be 100% sure that occurs.
> >
> >I hope I'm not making an incredibly daft mistake, so please correct
> >me if I'm wrong. :)
> >
> >--- In , Andrei Chichak <acpmiedm@t...>
wrote:
> > > Are you sure you want to measure PWM? A crank or cam sensor will
> >have a
> > > constant pulse width, the frequency varies with engine RPM.
> > >
> > > Andrei
> >
> >
> >
> >--------------------
> >
> >
> >
> >">http://docs.yahoo.com/info/terms/