Yeah, what he said!  Seriously, Russell is to be commended for
distilling a topic that has generated perhaps hundreds of posts,
down to it's essential elements.

This should be posted in the beginners FAQ so it doesn't need to
get rehashed every few months.

Says me.

Andrew


---- On Mon, 27 Sep 2004, Russell McMahon
(apptech@paradise.net.nz) wrote:

> > Just laying out my first PIC PCB, and I was wondering what
is the best 
> > thing to do with any unused I/O pins? Tie to GND, +5V or
leave 
> > unconnected? />
> 
> Big ongoing discussions about this.
> Much in archive.
> 
> Summary:
> 
> - Open inputs are very bad - avoid at all costs.
> - Open outputs are fine BUT software glitches can set them to
inputs and ...
> - Inputs tied low or high can glitch to outputs and draw much
current.
> - Resetting pins to their intended states occasionally helps
reduce above 
> problems.
> - Unless unused pin handling as above is well documented and
rigorously 
> followed it WILL catch you out sooner or later
> - Best of all operationally is to tie to low or high with
large value 
> resistors. Best of all worlds. Pins can be used subsequently
with ease. 
> Provision of resistors is annoying and takes space.
> 
> No one solution works perfectly but some are better than
others.
> 
> 
>         RM
>  
> 
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