> I am exploring very low power for various designs, yes.  But before I dit=
ch the
> use of pull-ups for something else, I wish to explore all the merits and
> demerits first.

If you are really after low power then you don't want any pull-ups.

Default state is set port to output with all pins at 0 (assuming switches a=
re to ground). When you need to read it set all pins to 1, do read and retu=
rn pins to 0. Yes the output FETS will see short circuit current for about =
5us while you do the read, but the average of that with 0 current over a si=
gnificant period of time will be much less than even the internal pull-ups.

Even if you read the switches each time the ignition is cycled, it will sti=
ll be a low average current. Cycling the ignition could be made a requireme=
nt for changing a setting.

Another advantage - no real estate taken up with resistors.



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