At 05:06 PM 2/16/2008, you wrote:
>I use PICs in classes. The PICs are on a PCB, but otherwise unprotected.
>The students buy the PCBs, so they can work at home. Informatics
>students can not be expected to know much about static electricity, so
>for all I know they might use it to comb their cat's hairs. I have hadd
>some pretty weird failures previous years, so it might be a good idea to
>put some form of protection on all PIC pins. My idea is a resistor to
>ground for each pin, but what value? Would 1M be sufficient, or should
>it be lower?
>
>And what about the one pins that probably won't like any load, even 1M:
>the oscillator input?
>
>Wouter van Ooijen

The 1M resistors will have no useful effect. I suspect you will reject
anything that I'd consider bulletproof for both cost and flexibility
reasons.

May I suggest that a portion of an early class dedicated to proper ESD
handling procedures could be the proper approach from a pedagogical as well
as a business viewpoint?

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com



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