[Diy_efi] 60-2 crank sensor algorythms - Detecting missing pu

[maier_markus at t-online.de]

Hi,

sounds reasonable for detecting the gap for the first time, if you have
a quite standard engine with a full battery. If your starting
(cranking), then there might be heavydynamics of the engine speed. Just
imagine, you have a kind of race engine with a high compression ration
and a low battery (or a small starter), then the engine isn't cranking
very smoothly. 

What I'm doing is the following: the system has to detect the gap (or
what it thinks the gap is) once. Then it starts te tooth counter (or
better it resets it). After 58 teeth, the gap has to re-occur. If it
does so, I know, that the gap was detected correctly. I'm checking for
the correct gap for three revoloutions of the crankshaft (may be a
little bit too much). If the gap was detected three times, then I allow
the system to fire the ignition coils. So there's a quite good
certainty, that I have detected the gap correctly.

Ciao
Markus


Sid.Young at qml.com.au schrieb:
> 
> Markus,
> 
> I am working on an algorithm at present that says if the
> timer elapsed is >
> 1 3/4 of the last time it is the missing tooth.
> 
> Does this sound feasable to you ?
> 
> 
> Sid Young
> Brisbane
> Australia
> 
> 
> 
> -----Original Message-----
> From: maier_markus at t-online.de
> [mailto:maier_markus at t-online.de]
> Sent: Thursday, 3 April 2003 9:08 PM
> To: Brian at lightprocessor.co.uk; List for general
> do-it-yourself EFI talk
> Subject: Re: [Diy_efi] 60-2 crank sensor algorythms
> 
> 
> Hi,
> 
> the algorithm is quite straight foward:
> 
> at every positive flange of the tooth, you get
> interrupted (by the uC
> pin input). Then you're determining the time for that
> tooth (by a timer
> or whatever is appropriate on your micro) and store the
> result in an
> array (with the size of three). Before storing it, you
> need to shift
> the current array contents by one.
> 
> The algorithm then to detrmine, if the missing teeth have
> been passed
> is very easy:
> 
> your array contains the times for the last three theeth
> t1, t2, t3
> 
> if t2 > t1 + t3 then the missing teeth is the overlast
> one, which is
> ok.
> if t1 > t2 + t3 then the gap was detected one tooth to
> early and you
> can run a compensation algorithm
> if t3 > t1 + t2 then the gap is detected one tooth too
> late and you can
> run another compensation algo.
> 
> Once you detected the gap, you can reset your main timer
> (that
> represents the crank angle) to zero and reload the
> timers, that control
> the inginition and injection pulses.
> 
> I have to admit, that I'm working with Infineons TriCore,
> that has
> plenty of hardware timers linked to each other, which
> makes things
> easier. But implementing that in software is also not a
> big deal.
> 
> Ciao
> Markus
> 
> 
> 
> Brian Sidebotham schrieb:
> > Hi all,
> > 
> >  I'm currently worked on a few bits that require me to
> > work with a 
> > bosch 60-2 crank angle sensor. Now the EFI332 project
> > uses the 
> > TPU section of the processor which looks like a fine
> > idea, but the 
> > code does not seem to be available from the site
> anymore
> > :(
> > 
> >  Anyway, I am using a different make of processor, and
> I
> > would like 
> > to get crank angle information without the need for a
> > TPU, but 
> > using standard timers, and external interrupts, etc.
> > 
> >  I wouldn't even mind doing a dedicated processor that
> > finds the 
> > two missing teeth, and outputs them so that they could
> > cause an 
> > interrupt on my main processor, and the CAS signal can
> be
> > 
> > connected to a timer input on my main processor to
> keep
> > track of 
> > engine angle.
> > 
> >  What has everyone else done?
> > 
> > Cheers, Brian Sidebotham.
> > 
> > 
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> >
> 
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