倒计时25秒.asm

是我在电子竞赛期间写的一些单片机汇编程序

	ORG 0000H
	AJMP MAIN
	ORG 000BH
	AJMP PIPO
	ORG 0100H

MAIN:
	MOV SP,#30H

	MOV 40H,#00H			;定时10ms
	MOV 41H,#25H
	
	MOV TMOD,#01H
	
	MOV TH0,#0D8H
	MOV TL0,#0F0H									
	
	SETB EA
	SETB ET0
	SETB TR0
	MOV R0,#41H	
	
CYCLE:
	LCALL DISP
	AJMP CYCLE

PIPO: 
	PUSH PSW
	PUSH ACC
						
	MOV TH0,#0D8H
	MOV TL0,#0F0H

	INC 40H      
	MOV A,40H
	CJNE A,#64H,RET0
	MOV 40H,#00H
	
	MOV A,41H
	DEC A
	CJNE A,#1FH,KK
	SUBB A,#06H

KK:	MOV 41H,A

	CJNE A,#0FH,KK1
	SUBB A,#06H
KK1:	
	MOV 41H,A
	CJNE A,#05H,KK2
	
	
KK2:	CJNE A,#0FFH,RET0
	MOV 41H,#25H

RET0:
	POP ACC
	POP PSW
	RETI

;显示子程序
DISP:	
		
	MOV A,@R0
	ANL A,#0FH
	ACALL TABLE
	MOV P2,A
	CLR P0.6
	ACALL DELAY
	SETB P0.6
	
	MOV A,@R0
	SWAP A
	ANL A,#0FH
	ACALL TABLE
	MOV P2,A
	CLR P0.5
	ACALL DELAY
	SETB P0.5

	RET
TABLE:
	INC A
	MOVC A,@A+PC
	RET     
DB 0C0H,0F9H,0A4H,0B0H,099H,092H,082H,0F8H,080H,090H	;0-9的段码
     

	
DELAY:	MOV	R3,#10H
DELAY0:	MOV	R4,#50H
DELAY1:	DJNZ	R4,DELAY1
		DJNZ	R3,DELAY0
RET

END