Hi All,=20
I'm new to PICs and am trying to "port" my Z80 assembler skills to
something that belongs in this century but am having problems with my
test program.
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Here it is:
            LIST p=3D16f877,c=3D140
        include "p16f877.inc"
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org        0
clrf        STATUS
goto      BootStart
org        4
ISR     goto        5                      ; Setup Interupt Address
org        5
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BootStart =20
clrf        PORTB
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            bsf        STATUS,RP0    ; set Page 1 for TRIS registers
            movlw   b'00000000'
            movwf   TRISB           ; set PORTB for all outputs
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            bcf        STATUS,RP0    ; back to page 0
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LoopAgain
        ;movlw   0x00
        ;movwf   PORTB           ; All PORTB bits off
        ;movlw   0xFF
        ;movwf   PORTB           ; All PORTB bits on
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        incf    W, 0                  ; W =3D W + 1
        movwf   PORTB           ; PORTB =3D W
        goto    LoopAgain
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        end
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Now I thought that 'incf W, 0' would perform a W=3DW+1 operation, and =
that
when it reached 255, it would simply start from 0 (since it's an 8-bit
register), but this doesn't seem to be the case.
If I use the 4 commented lines instead of the 3 lower ones, then I get a
nice square wave on all 8 I/O pins, so I know the PIC is working and
that my programmer is ok etc.
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All I expect the above test program to do is count in binary flashing 8
LEDs....
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So what stupid thing am I doing wrong...
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Any help much appreciated,
Joe
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