On Fri, 5 Dec 1997 18:08:19 -0000 Mark Birks <m.birks@OMNIBUS.CO.UK>
writes:
>Hi folks,
>
>I have JUST started playing around with my first (of many - hopefully)
>PIC projects.
>
>I simply wanted to flash an LED using a demo program which put the PIC
>to sleep :
>
>        LIST    P=16C64
>                                        ;WDT enabled
>             MOVLW   0
>             TRIS    6
>             OPTION
>LOOP    SLEEP
>             INCF    6,1
>             GOTO    LOOP
>             END
** snip**
Mark,
 The option and the tris registers are located in bank 1 of ram.
You must set RP0 in the status register to access them then switch
back to bank 0 to access port b.
I use the following at the beginning of all my programs:

#define         bank0   bcf     status,rp0
#define         bank1   bsf     status,rp0
Then in the program I type bank0 instead of bcf 3,5.
You also need to use the "include" file at the begining of you program
for the PIC that you are using.

Your code might then look like this:

list    p=16c64
        title "Your project title or ??"
        include p16c64.inc
#define         bank0   bcf     status,rp0
#define         bank1   bsf     status,rp0

start
        bank1           ;select bank 1 for direct addressing.
        movlw   0       ;clear w.
        TRISB           ;set all port b pins as outputs.
        OPTION          ;set all option register bits to 0.
        bank0           ;select bank 0 for direct addressing.
LOOP    SLEEP
                INCF            PORTB,f ;
                GOTO    LOOP    ;

        END
Using the include file allows you to use nomenclature like INCF PORTB
instead of INCF 6,1. Open the p16c64.inc file and look at it. You will
get
the idea.
You might also look at  fig 4-25 and the associated discussion of direct
and indirect addressing in the data sheets.

Keep at it and you'll be flashing leds in no time!

Jeff Scholz