If you've got extra money to throw at it you can always use a switching
regulator.  These (when well designed) tend to clean up very noisy power
supplies.

Aside from using bypass caps, you should try having a diode going into
the circuit (before the caps) so the car's electrical system doesn't
suck the power out when you have negative spikes.

The positive spikes can be taken care of with a zener diode before the
regulator.

-Adam

David Dunn wrote:

>i've got an automotive project based on a 16f877 that works fine in 99% of applications, but when i
>get it in a car with a magneto ignition, my PIC is freaking out .. resets / locks / jumps to random
>locations in code.
>
>Anybody have tips on what I should be doing to 'harden' the PIC against this kind of noise ? the only
>pins i haven't done anything with are RB6/RB7 which i need open for ICSP.  All other unused pins are
>grounded via 4.7k resistor.
>
>just general tips would  be great .. thanks !
>
>
>
>dld
>
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>
>
>
>

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