That's interesting.  Maybe I'm still just misunderstanding the data
sheet.

Still, when I use MPLAB's simulator, it shows the power up state of the
CMCON bits as 0, and when I actually program the PIC, it behaved the
same way.  (No PORTA digital I/O unless I explicitely set the CMCON
bits.)

Oh well, at least I found something that works.

Thanks,

Nick

> -----Original Message-----
> From: piclist-bounces@mit.edu 
> [mailto:piclist-bounces@mit.edu] On Behalf Of michael brown
> Sent: Saturday, April 02, 2005 1:30 AM
> To: Microcontroller discussion list - Public.
> Subject: Re: [PIC] Configuring RA2 for digital I/O on 16F88--solved
> 
> 
> 
> From: "Nick Kennedy"
> 
> 
> > OK, finally figured it out.
> >
> > Bits <2:0> of CMCON must be set to 111 if RA0, RA1, RA2 are 
> to be used 
> > as digital I/O.  I fell for the table in the data sheet that says
> these
> > bits are set (111) on POR and other resets.  That doesn't seem to be
> the
> > case.
> 
> Hmmm.....this would certainly be interesting.  I've been 
> using the 16F88 with those pins as digital i/o and I don't 
> initialize CMCON.  I just go with the POR value and it seems 
> to be working fine.  I do have to init ANSEL though.
> 
> The thing about this that intrigues me is that I had some 
> trouble at first something like you describe.  I attributed 
> it to a RMW issue since I had the pins somewhat loaded and 
> was using the 8MHz INTOSC.  I started using a shadow register 
> to manipulate the pins and all was fine after that.
> 
> > So table 5-1 titled "Initializing PORTA" should add a little CMCON 
> > action to go along with the TRISA and ANSEL stuff.
> 
> Since I also use sleep mode, I don't think the comparators 
> could possibly be on or I would have seen the excessive sleep 
> current.  (I did have a sleep current issue at first but it 
> was due to another unrelated
> matter)
> 
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