You can save some memory if you do "clrf porta" for mvlw b'00000' and mvwf porta


Felix Centeno
centella@telcel.net.ve
http://www.geocities.com/CapeCanaveral/Hangar/2372/

-----Original Message-----
From: Keiser Soze <keisersoze_@HOTMAIL.COM>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Martes 30 de Junio de 1998 08:51 PM
Subject: Re: for beginners


>Here's my first program that I wrote for the 16C84. (Sounds kind of like
>a pathetic trip down memory lane doesn't it?)
>It's nice and simple, assuming that you've got some LEDs connected to
>portb alternate ones turn on then they all turn off, then count down
>from 255 .............. I'm sure you can figure it out.
>
>        list    p=16c84
>        radix   hex
>
>;fuses set as: XT,Watchdog off,powerup timer on,code protect off
>;using 4MHz osc.
>
>status  equ     0x03
>porta   equ     0x05
>portb   equ     0x06
>count1  equ     0x0c
>count2  equ     0x0d
>count3  equ     0x0e
>count4  equ     0x0f
>trisa   equ     0x85
>trisb   equ     0x86
>rp0     equ     5
>
>
>
>start   bsf     status,rp0      ;switch to bank 1
>        movlw   b'00000000'
>        movwf   trisa           ;set ports a&b
>        movwf   trisb           ;to all outputs (don't care about porta)
>        bcf     status,rp0      ;switch to bank 0
>        movlw   b'0000000'
>        movwf   porta           ;set all
>        movwf   portb           ;  outputs to zero
>        call    alt_on
>        call    del_0.2
>        call    all_off
>        call    del_0.2
>        call    dec_led
>no_end  call    alt_on
>        call    del_2
>        call    alt2_on
>        call    del_2
>        call    all_off
>        call    del_2
>        goto    no_end
>
>
>;--------------------
>;subroutines
>;--------------------
>alt_on  movlw   0aah            ;put bit pattern 10101010
>        movwf   portb           ;on leds
>        return
>
>alt2_on movlw   055h            ;put bit pattern 01010101
>        movwf   portb           ;on leds
>        return
>
>all_off clrf    portb           ;clear leds
>        return
>
>
>dec_led movlw   0ffh            ;set count1 to ffh
>        movwf   count1
>loop1   movfw   count1          ;required for repeat
>        movwf   portb           ;display current value of count1 on leds
>        call    del_0.2         ;pause for ~0.2 seconds to allow count down to
be
>observed
>        decfsz  count1,f        ;dec count1, if zero return from subroutine
else goto
>loop1
>        goto    loop1
>        return                  ;value displayed on leds will be 001h
>
>;----------------------
>;Delays below:
>;----------------------
>del_750 movlw   0ffh            ;750microseconds
>        movwf   count2
>loop2   decfsz  count2,f
>        goto    loop2
>        return
>
>
>del_0.2 movlw   0ffh            ;0.19125seconds
>        movwf   count3
>loop3   call    del_750
>        decfsz  count3,f
>        goto    loop3
>        return
>
>del_2   movlw   00ah            ;1.9125seconds
>        movwf   count4
>loop4   call    del_0.2
>        decfsz  count4,f
>        goto    loop4
>        return
>;-----------------------
>        end
>
>
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