[Efi332] ITC and PMA/PMM timing relationship.

[bowtievette at aol.com]

Hi Andrei,
 
My experience is all with PMMX?, PSP? etc, I assume that is what you are using.
 
By "sycnchronization" I assume you mean you are having trouble getting PMMX's 720 degree counter to respond properly to your cam synch signal (and adjust its counter to align with the position in the engine cycle) and not PMMX's 58xx crank wheel pattern synching. I assume that your PMMX is synching up fine to the crank 58xx pulsetrain.
 
When I was using the 720 degree configuration (I just use the 360 degree counter now), I was sending the cam sync HSR a few teeth prior to the gap. I don't think its critical at all where, but there is alot more going on in the PMMX function during the missing gap and perhaps there is something in there that prevents the counter adjustment from working properly during this period. I don't recall having any issues getting it to work outside the gap.
 
As far as the ITC pulse duration goes, that should not matter. Its a two part deal to get this to work. First, cam synch is sensed by ITC on either the leading or trailing edge depending on how it is configured. As long as ITC "sees" the transition, the duration or location of the pulse preceding or following should not matter to it. Also, you must have ITC configured to generate an interrupt at this event. The second part of the job is for the ISR to then issue the HSR to PMMX to reset its tooth counter according to the formula shown in the documentation. ITC and PMMX are not formally linked by any other mechanism other than the CPU responding to the interrupt.
 
HTH, jc
 
-----Original Message-----
From: andreic at chichak.ca
To: efi332 at diy-efi.org
Sent: Thu, 28 Dec 2006 2:35 PM
Subject: [Efi332] ITC and PMA/PMM timing relationship.


Hi all, 
 
I seem to be having a bit of problem getting synchronization when 
using ITC and PMM. My signal source sends out a pulse to the ITC 
channel just before the missing tooth event on the PMM channel. 
 
Does the '332 expect the ITC pulse to span the missing tooth event? 
 
How early does the ITC pulse leading edge need to happen? 
 
How late does the ITC pulse falling edge need to be? 
 
Thanks, 
Andrei 
 
 
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