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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