Micro Sys. Lab 4 Ex. 02 - Computed Delay (1s)

    #INCLUDE "P16F84A.INC"

    __CONFIG _XT_OSC & _WDT_OFF & _PWRTE_ON & _CP_OFF

    ERRORLEVEL -302

    ;----------------------------------------------------------
    ;   variable declaration
    COUNTERA EQU H'10'
    COUNTERB EQU H'11'

    ORG 0x00
    GOTO START

    ORG 0x04
    GOTO START

START
    ;----------------------------------------------------------
    ;   register configurations
    BSF STATUS, RP0
    MOVLW 0x00
    MOVWF TRISB

    MOVLW 0x07
    MOVWF OPTION_REG

    BCF STATUS, RP0
    CLRF PORTB

MAIN
    ;---------------------------------------------------------
    ;   loop of the program

    MOVLW 0xF0
    MOVWF PORTB
    CALL DELAY

    MOVLW 0x0F
    MOVWF PORTB
    CALL DELAY

    GOTO MAIN

DELAY
    ;---------------------------------------------------------
    ;   create a delay
    MOVLW D'1'
    MOVWF COUNTERA

LOOPA
    CALL DELAYA
    DECFSZ COUNTERA, 1
    GOTO LOOPA
    RETLW 0x00

DELAYA
    MOVLW D'15'
    MOVWF COUNTERB

LOOPB
    CALL DELAYB
    DECFSZ COUNTERB, 1
    GOTO LOOPB
    RETLW 0x00

DELAYB
    CLRF TMR0
    BCF INTCON, T0IF
LOOPC
    BTFSS INTCON, T0IF
    GOTO LOOPC
    RETLW 0x00

    END