Perhaps is good to explain that any PIC pin which receive data while the
PIC is in sleep, acts like a power supply pin through the internal diode
connected between the pin to the VDD. (there is another one connected
between pin to GND). It does not matter you have or not external pull-up as
long it has enough large resistor value.

Once you set as output and drive low the input pin, the current path to the
VDD dissappears. Nothing fancy.

best wishes,
Vasile

On Wed, Sep 2, 2015 at 10:23 PM, Bob Ammerman <picram@roadrunner.com> wrote=
:

> Um...
>
> And obviously you should also drive the TX pin low if it isn't already.
>
> ~ Bob Ammerman
> RAm Systems
>
> > -----Original Message-----
> > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behal=
f
> > Of Bob Ammerman
> > Sent: Wednesday, September 02, 2015 11:16 AM
> > To: 'Microcontroller discussion list - Public.' <piclist@mit.edu>
> > Subject: RE: [PIC] Current Consumption in Sleep
> >
> > > Thanks.  It looks like my first step should probably to reconfigure
> > > the
> > project
> > > so I'm using the PIC's EUSART rather than bit-banging it.
> > >
> > > John Hansen
> >
> > You shouldn't have to do that.
> >
> > Just do the following to power down:
> >
> > 1: Power down the MAX232
> > 2: Set the RX pin to an output and drive it low.
> >
> > The only issue I can see is that the caps on the MAX232 might feed back
> thru
> > the MAX232 and induce a voltage on the RX line coming from the MAX232 t=
o
> > the RX pin. This could result in unacceptable current on the RX pin of
> the
> PIC
> > when you drive it low. I would just put a 3.3K resistor between the PIC=
's
> RX
> > pin and the MAX232 to avoid this issue (if it is indeed an issue).
> >
> > ~ Bob Ammerman
> > RAm Systems
> >
> >
> > --
> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
>
> --
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