Oh yes, if you want to be thorough:

       banksel TRISA  ; Select proper bank
       movlw   0xFF   ; will set port to all inputs
       errorlevel -302  ; suppress stupid message
       movwf   TRISA  ; set the port
       errorlevel +302  ; re-enable the message in case we screw up later
       banksel PORTA  ; Select the bank containing PORTA
    ; NOW we can read the puppy
      movf   PORTA,W

72/73 de WB8RCR    http://www.qsl.net/wb8rcr
didileydadidah     QRP-L #1446 Code Warriors #35


----- Original Message -----
From: "John J. McDonough" <wb8rcr@ARRL.NET>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, February 09, 2004 2:25 PM
Subject: Re: [PIC:] Reading PortA on 16F877


> Your code will work fine on a 16f84, and will work on an 877 if you are in
> bank 0 or 1 (only) - remember the 877 has four banks.  You assume RP1 to
be
> clear.  On an 877, RP2 is guaranteed clear and TRISA is in bank 1, but
maybe
> not in some other part.
>
> However,
>
>       banksel TRISA
>       movlw   0xFF
>       movwf   TRISA
>       banksel PORTA
>
> will work in any case.
>
> 72/73 de WB8RCR    http://www.qsl.net/wb8rcr
> didileydadidah     QRP-L #1446 Code Warriors #35
>
> ----- Original Message -----
> From: "Paul James E." <jamesp@INTERTEX.NET>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Monday, February 09, 2004 1:59 AM
> Subject: Re: [PIC:] Reading PortA on 16F877
>
>
> > I'm not sure what BANKSEL PORTA is supposed to do.
> >  Do a
> >      bsf     STATUS, RP0
> >      movlw   0xFF
> >      movwf   TRISA
> >      bcf     STATUS, RP0
> >
> >  This will setup PORTA as all inputs.
> >
> >      Then to read the port, just do a movf 0x05, 0
> >
> >  This will move the contents of PORTA into the 'w' register.
> >
> >  Then do with 'w' what you need to do.
> >
> >          Regards,
> >
> >            Jim
> >
> >
> >
> > > -----BEGIN PGP SIGNED MESSAGE-----
> > > Hash: SHA1
> > >
> > >
> > > I want to read either PortA or PortE on a 16F877 chip as digital
input.
> > >
> > > I have read the PortA, PortE, and A/D sections of 30292c.pdf
> > > In particular, I have read p113.
> > > On page 218, there is an example to use PortA.  I have not done the
> > > CLRF PortA shown in the example, but otherwise comply.  I will try
this
> > > in the next cycle.
> > >
> > > I have set ADCON1 to 0x06 and verified this with read and display to
> > > LEDs. I have set  and verified TRISA to 0x3F
> > >
> > > I do a very simple
> > >          banksel PORTA
> > >          movf    PORTA,w
> > >          banksel PORTD           ;home of the LEDs.
> > >          movwf   PORTD
> > >
> > > The LEDs are always dark.  I have success with PORTC as an input.
> > >
> > > Thoughts?
> > >
> > >
> > > - --
> > > Aubrey McIntosh, Ph.D.
> > >
> > >
> > > -----BEGIN PGP SIGNATURE-----
> > > Version: PGPfreeware 7.0.3 for non-commercial use <http://www.pgp.com>
> > >
> > > iQA/AwUBQCe2FwKlSw8yssF7EQKtwgCeJkH1LfsMeQzKfAIbhTNbV22kqvQAn3bS
> > > eZLvXCkZhjwOSI+CpLj8fz3n
> > > =kizK
> > > -----END PGP SIGNATURE-----
> > >
> > > --
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> >
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