At 12:19 PM 7/09/98 +1000, you wrote:
>Fundamentally,
>a good layout will solve most problems.
>
>If you have the luxury of time and money, design a double sided pcb and use
>one side for grond connections plane only and all other nets connect by
>shortest route on the top. Fill any ramining areas on the top with ground
>plain. DO NOT AUTOROUTE!
>
>I have successfully used this method for automotive "under bonnet" pcbs for
>OEM products as well as a PIC products of my own wich is sitting next to a
>piezo electric ignitor for stove tops.
>
>Dale
>

Yes, correct Dale but it is not the whole story,
One MUST remember that this is only part of the solution. Good software
design is essential to ensure that the device continues to operate in either
favorable or un favourable conditions for the longest possible time. This
process includes many items that start from the basics:-

1/      Always reloading the Port direction registers
2/      The use of constants rather than calculating
3/      Reloading port values
4/      Re enabling I/O and control registers
5/      Removing assumptions (eg. This bit should be set, so don't set it again)
6/      The use of watchdogs

These can be expanded more and then leads off to crash recovery and crash
detection. Often crashes are subtle, and may involve a simple memory
corruption. If one is lucky, then the system will reset and things will be OK?

<Flame suit on>
One of the best pieces of advice that a lecture gave me was "The only
assumption that you can make is that your software may be used in a
situation where peoples lives will depend on it" OK, so it is a bit over the
top, but I hope that the basic idea is seen.
<Off>

By default many people will use the basics, perhaps without even knowing
they do.


As for under bonnet stuff. This does depend on location! I have used good
old vero board for development in the engine bay of modern cars with no
problems. Put the board near the spark plug end of a HT lead and things are
different. I have also seen very well layed out boards fail when placed near
the fuel pump line (PWM drive from the ECU), alas, it required input
conditioning!


Dennis