I think its taken out of context....when they say that, its for testing
conditions I believe.  For worst case power consumption's and such, or to
measure prop delays, they must state those conditions such that a designer
could duplicate it.

What page of the data sheet did you read that on?

-----Original Message-----
From: David Covick [mailto:dac@WEST.NET]
Sent: Wednesday, September 22, 1999 7:56 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: What to do with PINs not used


Harrison,

What do I do with the statement in the Microchip data sheet that says "with
all I/O pins in hi-impedance state and tied to Vdd or Vss"??

David



> Why does this come up every 6 months or so???
>
> NO!!!  Don't tie them to anything!  Define them as OUTPUTS, and set them
to
> default as low.
>
> Why?  Because, these are I/O pins.  Unless its a dedicated input pin,
don't
> tie it because at somepoint two things might happen.  First, an
unprogrammed
> chip might be put into the circuit, and I don't recall if by default the
> pins are input or outputs.  If tied either way, they could might drive Vcc
> to Vss, or the other way around.
>
> Second, if you need to use that pin for something else down the road, you
> have to then isolate it first and wire it up.
>
> Most programmable logic devices define unused pins as no connects, as they
> tristate or isolate the pins when they burn them.
>
> Just my .02 worth.  Everyone has their own ideas on what to do....
>