Actividad 3 - Programación de un microcontrolador de 8 bits

Problema:

Al microcontrolador PIC16F84A conectar un led al pin RB7. El programa deberá encender y apagar ese led cada 200ms aproximadamente (+/- 5%), usando un clock a cristal de 4MHz.

Dibujar el esquemático en el KICAD

Programar en lenguaje assembler al microcontrolador con el MPLAB, resolviendo el problema 

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;Actividad 3.asm
;El programa hace parpadear a una Led conectado a RB7
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    LIST    p=PIC16F84A
    INCLUDE    <p16f84a.inc>
    __CONFIG _WDT_OFF & _PWRTE_ON & _CP_OFF & _XT_OSC;    CONFIG es donde configuramos el tipo de oscilación que vamos a usar
    ERRORLEVEL    -302
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 ;Equivalencias:
#DEFINE    BANK0    bcf    STATUS,RP0        ; Cambio al banco 0
#DEFINE    BANK1    bsf    STATUS,RP0        ; Cambio al banco 1  

SW        EQU        0
LED        EQU        7
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; Variables
    CBLOCK 0x00   
    d1
    d2
    ENDC
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; Vectores
    ORG    0x000
    goto Inicio        ; Vector de Reset
 
    ORG 0x004
    goto Isr        ; Vector de Interrupción
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; Rutina de servicio de interrupción
Isr
    retfie
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Inicio    ; Configuramos el bit 7 (Port B) como salida (RB7)
    bsf STATUS,RP0
    bcf TRISB,LED
    bcf STATUS,RP0

Principal
    bcf PORTB, LED
    call Delay_200ms
    bsf PORTB, LED
    call Delay_200ms
    goto Principal
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; Sub-Rutinas

; Delay = 0.2 seconds
; Clock frequency = 4 MHz

; Actual delay = 0.2 seconds = 200000 cycles
; Error = 0 %
Delay_200ms
            ;199993 cycles
    movlw    0x3E
    movwf    d1
    movlw    0x9D
    movwf    d2
Delay_200ms_0
    decfsz    d1, f
    goto    $+2
    decfsz    d2, f
    goto    Delay_200ms_0

            ;3 cycles
    goto    $+1
    nop

            ;4 cycles (including call)
    return

END

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