;********************************************************************************
;999999計數器的另一種形式。          .數碼管數據p0,數碼管控制p2口               *
;********************************************************************************
;*  日期:  2007-3-25                                                            *
;*  版本:  3.0                                                                  *
;*  作者:  深圳學林電子有限公司     專業8051單片機教學站                        *
;*  郵箱: sxj1974@163.com                                                       *
;*  網站： http://www.51c51.com     http://www.8951.com    更多例程請登陸網站   *
;********************************************************************************
;*  硬件：此程序在本公司xlisp系列單片機實驗儀運行通過                           *
;********************************************************************************
;* 【版權】 Copyright(C)深圳學林電子有限公司 www.51c51.com  All Rights Reserved *
;* 【聲明】 此程序僅用于學習與參考，引用請注明版權和作者信息！                  *
;********************************************************************************

	ORG	0000H
	AJMP	MAIN
	ORG	0030H
MAIN:
	MOV	30H,#00H	;30h--33h is a buffer for four 7-segment led display.
	MOV	31H,#00H	;at the beginning,the four 7-seg led all diaplay zero.
	MOV	32H,#00H
	MOV	33H,#00H
	MOV	DPTR,#TAB
MAIN1:
	mov	35h,#10
lop1:
	MOV	34H,#00		;34h and 35h is a counter for control the counter time.the 00h equal 256.
LOOP:
	MOV	A,30H
	MOVC	A,@A+DPTR
	SETB	P2.1
	CLR 	P2.6
	MOV 	P0,A
	LCALL 	DELAY 
	MOV 	P0,#0FFH	;display the lowest 7-seg led.	
	MOV	A,31H
	MOVC	A,@A+DPTR
	SETB	P2.6
	CLR	P2.5
	MOV 	P0,A 
	LCALL 	DELAY
	MOV 	P0,#0FFH
	MOV	A,32H
	MOVC	A,@A+DPTR
	SETB	P2.5
	CLR	P2.4
	MOV 	P0,A  
	LCALL 	DELAY
	MOV 	P0,#0FFH
	MOV	A,33H
	MOVC	A,@A+DPTR
	SETB	P2.4
	CLR	P2.3
	MOV 	P0,A  
	LCALL 	DELAY
	MOV 	P0,#0FFH	;display the highest 7-seg led.
	SETB	P2.3
	CLR	P2.2
	MOV 	P0,#28h
	LCALL 	DELAY
	MOV 	P0,#0FFH	;display the highest 7-seg led.
	SETB	P2.2
	CLR	P2.1
	MOV 	P0,#28h
	LCALL 	DELAY
	MOV 	P0,#0FFH	;display the highest 7-seg led.	
	DJNZ	34H,LOOP	;scan one time,34h decrease one,if 34h decrease to zero,the buffer content will change.
	djnz	35h,lop1	
	INC	30H
	MOV	A,30H
	CJNE	A,#10,MAIN1
	MOV	30H,#00H	;if 30h increase to 10,then clear 30h and increase 31h.
	INC	31H
	MOV	A,31H
	CJNE	A,#10,MAIN1
	MOV	31H,#00H	;if 31h increase to 10,then clear 31h and increase 32h.	
	INC	32H
	MOV	A,32H
	CJNE	A,#10,MAIN1
	MOV	32H,#00H	;if 32h increase to 10,then clear 32h and increase 33h.	
	INC	33H
	MOV	A,33H
	CJNE	A,#10,MAIN2
	MOV	33H,#00H	;if 33h increase to 10,then clear 33h and jump to main.
	AJMP	MAIN
main2:	ajmp	main1
DELAY:
	CLR	P3.3
	MOV	R7,#2
	NOP
	NOP
D1:	MOV	R6,#2
	SETB	P3.3
D2:	DJNZ	R6,D2
	CLR	P3.3
	DJNZ	R7,D1
	SETB	P3.3
	RET
TAB:
	DB	28H,7EH,0A2H,62H,74H,61H,21H,7AH,20H,60H	
	
	END