For one thing, I'm guessing that the WDT intervals in some automotive
products are _very_ short.

Also, a lot of effort goes into making things fail intelligently. For
example, if an engine sensor goes bad, the engine control computer will
usually be able to limp along allowing you to get the car in for service.
(the famous 'check engine light' scenario).

I've run into similar things in my work on power plants. Basically very
simple, highly reliable systems are capable of keeping things running when
the more complex advanced systems fail.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)



----- Original Message -----
From: Bruce Cannon <brucecannon@HOME.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Wednesday, September 20, 2000 12:44 PM
Subject: Re: [PIC]:Reinitializing registers on reset (was New to this world)


> Bob, it's something I've been worrying about for a while; in Mchip
seminars
> they tell me to "think robust", and always reinitialize in all sorts of
> different situations, but it really troubles me because if ANY register is
> corrupt then you must assume they ALL might be corrupt, right?  I'd like
to
> learn more about how they do it in the auto world, where there's bootloads
> of trauma circulating around...
>
> Bruce Cannon
> Style Management Systems
> http://siliconcrucible.com
> (510) 787-6870
> 1228 Ceres ST Crockett CA 94525
>
> Remember: electronics is changing your world...for good!
>
> > Ok, the MChip spec sheets go to great trouble to define the state
> > of various
> > registers on a reset.
> >
> > The 'wisdom' here is that you ignore that and reinitialize them anyway.
> >
> > Is this really needed?
> >
> > What next, are we going to assume that ADDWF won't correctly add 2 + 2.
> >
> > When you start doubting that a chip is following spec in one
> > area, you have
> > to, for consistency, assume it could fail in any other area.
> >
> > Bob Ammerman
> > RAm Systems
> > (contract development of high performance, high function, low-level
> > software)
>
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