which you will probably be doing if you are doing I2C.
----- Original Message -----
From: "Michael Rigby-Jones" <mrjones@NORTELNETWORKS.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, March 19, 2001 10:00 AM
Subject: Re: [PIC]: I2C pullups


> > -----Original Message-----
> > From: Kevin Blain [SMTP:kevinb@WOODANDDOUGLAS.CO.UK]
> > Sent: Monday, March 19, 2001 9:24 AM
> > To:   PICLIST@MITVMA.MIT.EDU
> > Subject:      Re: [PIC]: I2C pullups
> >
> > When you TRIS a pin as input, then read it, does that not put a logic 1
in
> > the PORT register if the pin is pulled up? If so, when the pin is TRIS'd
> > to
> > output again, it will be outputting logic 1.??
> >
> The port latch is only changed if a Write or Read Modify Write instruction
> is executed on the port.  So if a pin is set as an input, and then a
BSF/BCF
> etc is performed on the port, the port latch for that pin will be set to
> whatever state the pin is at.  This won't happen by simply reading the
state
> of the port however.
>
> Regards
>
> Mike
>
>
> > Therefore, care should be taken when doing I2C in this method to make
sure
> > that the pin is set to output 0 whenever you tris back to an output.
> >
> > Regards, Kevin.
> >
> > --
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