AVR-Chat

Best bet is to diode protect (for polarity) the input to an 
opto-isoltor on each GPIO.  This will protect you against
static discharge, excessive positive or negative inout, etc, etc., at 
very little cost.  Cost of  a single diode, and a $0.25 (US) opto-isolator.

tom


Ryan wrote:
>
> Thanks, I know exactly what you're talking about. However, for
> someone who might inadvertantly connect a +12V supply to the pin... It
> would obviously try to sink lots of current through the diode, likely
> blowing it up, then blowing up the MCU. Would the effectiveness be
> reduced by putting series resistors (say, 1k?) with the two diodes?
>
> Or if the supply was connected backwards, all the current would try to
> go through both diodes.... Trying to create an idiot proof box, but
> you know how that goes. ;)
>
> .
>
> 
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