At 01:31 PM 9/26/2004 +0100, you wrote:
>Hi all,
>
>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?
>
>Cheers all

If they *can* be programmed as outputs, leave them unconnected (or possibly
run them to an unstuffed header). Don't forget to set the TRIS registers to
make them outputs early in your program.

If they can only be inputs, tie them directly to Gnd or 5V (or through a
resistor if you might change your mind). You can also run them (in parallel)
to the above-mentioned header footprint.

The idea of the header is that later you may wish to add a featur to the
product/project or to use the board design for a one-off that you didn't
anticipate. Having a clean way to connect to those unused pins makes things
easier.

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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