Anthony and alla others, Thank you very much following the tips I got the
code working. the 1us delay is't critical,since both signals are feded into
a decoder. thanks guys


>From: Anthony Fremont <spam-me@HOUSTON.RR.COM>
>Reply-To: pic microcontroller discussion list <PICLIST@MITVMA.MIT.EDU>
>To: PICLIST@MITVMA.MIT.EDU
>Subject: Re: [PIC:] simple code question
>Date: Wed, 18 Aug 2004 10:04:07 -0500
>
>From: "Aslam Jallali"
>
>
> > Hi to every one of you every where
> > A Very concrete question: If in the following code I want to clear bit 4
>and
> > bit 3 and then call the delay and then set both bit 3 and 4 Basically,
> > instead of one pin at the time I want to make two pins high or low  How
>can
> > I do this?
>
>Depending upon your timing constraints, several different ways.
>
> > Would simply bcf  PORTC, 4,3 work?
>
>No.
>
> > Not to waste your time I spare you with the rest just straight to the
>loop:)
> > ; LED FLASH LOOP
> >
> > Loop
> >         bcf PORTC,4     ; RC4 = low = led on
>
>You could just simply add a "bcf PORTC,3" right here, unless the 1uS
>(assuming 4mhz clock) delay is a problem.  If you need them to change at
>the
>same exact time, then change the "bcf PORTC,4" statement above to:
>
>         movlw    b'00011000'
>         andwf    PORTC, F
>
> >         call Delay
> >
> >         bsf PORTC,4     ; RC4 = high = led off
>
>Same as before, either add a "bsf PORTC,3" right here, or change the "bsf
>PORTC,4" above to:
>
>         movlw    b'00011000'
>         iorwf    PORTC, F
>
> >         call Delay
> >         goto Loop
>
>Since you don't seem to be worried about the extra delay added by this
>goto,
>you could aparently do it either way you choose.  I would recommend you go
>with the AND's and OR's as I feel that it is more clear (but that's just me
>;-)
>
>Others here will point out that you should probably use "shadow" registers
>instead of directly modifying the individual pins on the output port.
>Search for RMW (read-modify-write) issues for reasons why.  You may also
>wish to use an "equ" pseudo-op or "#define" to define the bit mask, that
>way
>if it ever changes you just have to fix one line in the source and then
>re-assemble it, instead of hunting down every place you used the bit mask
>and having to fix them one-by-one.
>
>--
>http://www.piclist.com hint: To leave the PICList
>mailto:piclist-unsubscribe-request@mitvma.mit.edu

_________________________________________________________________
The new MSN 8: advanced junk mail protection and 2 months FREE*
http://join.msn.com/?page=features/junkmail

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics