On 2/16/08, wouter van ooijen <wouter@voti.nl> 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?

Your luck is that both you and yours students are living in The Netherlands.
If you'll protect with 1M for ESD in the US, will be useless. (in fact
be glad you're not living at NY, believe me, I'm here from one week
and I'm anxious to leave...)

1M to the ground will be not good and not bad. A student will always
find a good way to fry the PIC. Here we have used series resistors and
small capacitors to ground. But you can't use those on *all* pic pins.
So, use a socket, do not protect anything and sell them hundreds of PIC's.

Vasile
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