Config Proteus like this
And here is the source code
;; -----------------------------------------------------------------------------
;; File name: 7SegmentsLedx4_Counter.asm
;; Email: dmtmd2010@yahoo.com.vn
;; Blog: tdmblogging.blogspot.com
;; Date: March 3rd, 2014
;; Description: a simple counter from 0000 to 9999 using PIC16F877A and 7 segments leds.
;; -----------------------------------------------------------------------------
include P16F877A.inc
; define constants
num_0 equ 20
num_1 equ 21
num_2 equ 22
num_3 equ 23
time_delay equ 24
time_delay1 equ 25
time_delay2 equ 26
counter equ 27
rate equ 28
tmp equ 29
org 0
goto 100
org 10
table ; look up for 7 segments code
movfw counter
addwf PCL
retlw H'3F' ; 0
retlw H'06' ; 1
retlw H'5B' ; 2
retlw H'4F' ; 3
retlw H'66' ; 4
retlw H'6D' ; 5
retlw H'7D' ; 6
retlw H'07' ; 7
retlw H'7F' ; 8
retlw H'6F' ; 9
org 100
start
; config and init ports
bsf STATUS, 5 ; select bank 1
clrw
movwf TRISB ; mark port B as an output port
movwf TRISC ; mark port C as an output port
bcf STATUS, 5 ; select bank 0
clrf PORTB
clrf num_0
clrf num_1
clrf num_2
clrf num_3
clrf rate
movlw H'FF'
movwf PORTC
; main program start here
loop
; control the counting speed
incf rate ; increase rate
btfsc rate, 6 ; if rate equals 01000000
call incNum0 ; do count
btfsc rate, 6 ; and then clear rate
clrf rate
call display ; scan the leds
goto loop
display
bsf PORTC, 0 ; port C equals 11111111
movf num_0, w ; look for the 7 segments code of num_0 value
movwf counter
call table
movwf PORTB ; display to port B
bcf PORTC, 3 ; port C equals 11110111
call delay
bsf PORTC, 3
movf num_1, w
movwf counter
call table
movwf PORTB
bcf PORTC, 2
call delay
bsf PORTC, 2
movf num_2, w
movwf counter
call table
movwf PORTB
bcf PORTC, 1
call delay
bsf PORTC, 1
movf num_3, w
movwf counter
call table
movwf PORTB
bcf PORTC, 0
call delay
return
incNum0
incf num_0 increase num_0
; test if num_0 equals 10 (1010 in binary)
clrf tmp
btfsc num_0, 1 ; xxxxxx1x
bsf tmp, 0
btfsc num_0, 3 ; xxxx1xxx
incf tmp
btfsc tmp, 1
call incNum1 ; num_0 = 10 -> increase the next
return
incNum1
clrf num_0
incf num_1
clrf tmp
btfsc num_1, 1
bsf tmp, 0
btfsc num_1, 3
incf tmp
btfsc tmp, 1
call incNum2
return
incNum2
clrf num_1
incf num_2
clrf tmp
btfsc num_2, 1
bsf tmp, 0
btfsc num_2, 3
incf tmp
btfsc tmp, 1
call incNum3
return
incNum3
clrf num_2
incf num_3
clrf tmp
btfsc num_3, 1
bsf tmp, 0
btfsc num_3, 3
incf tmp
btfsc tmp, 1
clrf num_3
return
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
delay
movlw H'5'
movwf time_delay2
delay3
movlw H'5'
movwf time_delay1
delay2
movlw H'5'
movwf time_delay
delay1
decfsz time_delay
goto delay1
decfsz time_delay1
goto delay2
decfsz time_delay2
goto delay3
return
END
