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Editorial Team
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Asked: 2026-05-29T14:50:05+00:00

The embedded system in question is the PIC 16F877 and I’m trying to increment

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The embedded system in question is the PIC 16F877 and I’m trying to increment the PORTC register with incfsz but it remains at 0. The tutorial says this is possible but I can’t get it to work. 

list p=16f877
include "p16f877.inc"

__CONFIG    _CP_OFF & _CPD_OFF & _LVP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_OFF & _XT_OSC


org 0x000           ; Start at the reset vector
nop                 ; Reserved for ICD in debu mode

Init
banksel PORTC
clrf    PORTC       ; Clear PORTC initially


; Set up the Timer0 control register

banksel OPTION_REG
movlw   B'10000111' ; Internal clock, prescaler assigned to Timer0
movwf   OPTION_REG  ; prescaler, 1:256

clrf    TRISC       ; PORTC all output  

banksel PORTC       ; Back to Bank 0

movlw   B'00000000'
Main

; Timer0 delay for acquisition


btfss   INTCON,T0IF ; Loop until T0IF = 1 (TMR0 rollover)
goto    Main
bcf     INTCON,T0IF
incfsz  PORTC , F  
goto Main


LoopWhilePushed         ; Loop if PORTB<0> = 0 (pressed)

btfss   PORTB,0
goto    LoopWhilePushed

goto    Main        ; Do it again

end
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1 Answer

  1. Editorial Team

    As a novice I cant do that, so I gave up on PORTC and defined a constant, incremented that and moved that WORKING regsiter into portc and got the same results. Yep Im a quitter.

    UPDATE: As it turns out this it was subtle a hardware error that allowed all of the other experiments to function but prevent this one from working. It was not discovered until the circuit was rewired out of spite.

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