Multiprocessor system

[Brian Warburton, c/o Turbo Systems Ltd]

> Would it be possible to make some sort of FIFO structure that kept track of
>the time to go into the output compare, and a mask to tell you which
>injector to be turned off? Given that you know how many cylinders you have(I
>hope :), the FIFO can be of a fixed size:2 bytes for OC value, 1 for mask per
>cylinder, with an extra pair of bytes to tell you where the beginning and
>end of the valid info is. Every time the OC was triggered, it could load the
>next value from the queue into the OC. You'd need an available output port
>to do this, but I think it could be done. One potential problem would be if
>two injectors were to be closed in a time frame shorter than the length of
>time for the interupt to be serviced. This shouldnt be too much a problem if
>the OC is kept as a high priority, and the interrupts aren't too long. How
>does the aftermarket deal with this? Or do they use chips with more output
>compares?

Can't remember who it was that asked for more info/details on the
80c196 for automotive use,but the note above has pretty adequately
described the functionality of the HSO unit on the more base-level
80c196 chips. (The newer/later ones have even more super-duper I/O
and interrupt hardware). On the "base-level" 80ca96 chip, you have a
hardware carousel which you throw output requests and times in and
the hardware does the rest. Every tick it checks every entry in the
carousel, when it finds one due it takes the appropriate
output action and then (optionally) deletes the request from the
carousel. One output compare driving a multitude of o/p pins and
or software interrupts. The HSI system works in a similar way for
inputs, it time-tags them and sticks them in a FIFO ready for the
s/w to read when required.

The Ford 8061/8065's work in the same way but have more carousel
slots available. All in all the Ford chips outperform the 80c196
series in a lot of ways which is surprising considering the
8096/80c196 were based on the Ford chips.


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Brian Warburton,   "Still searching for the perfect curve....."
email: bwarb at turbo.win-uk.net
                               Advanced Automotive Electronics Ltd,
                               Van-Nuys House, Scotlands Drive,
                               Farnham Common, England.  SL2-3ES
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