p8_1.asm

单片机原理与应用实例教程 单片机原理与应用实例教程

		ORG		0000H
		LJMP	MAIN

		ORG		0003H			;外部中断0的入口地址
		LJMP	INT_0

		ORG		4100H
MAIN:	MOV IE, #10000001B		;令EA=1，EX0=1
		SETB IT0				;设置触发模式
		MOV R0, #1				;设置标志位
		MOV A, #0FEH    		;左边第一个开始显示
LOOP:	CJNE R0, #0H, LEFT		
		RL A	   				;左移
		AJMP DELAYS
LEFT:   RR A					;右移

DELAYS: MOV P1, A
		ACALL DELAY
		ACALL DELAY
		ACALL DELAY
		ACALL DELAY
		ACALL DELAY
        AJMP LOOP

DELAY:	MOV R7,#82H				;延迟程序
DL1:	MOV R6,#0FFH
DL2:	NOP
		DJNZ R6,DL2
		DJNZ R7,DL1
		RET

INT_0:	CLR EX0
		ACALL DELAY
		SETB EX0
		CJNE R0, #0H, SETR0_1
		MOV R0, #1
		RETI
SETR0_1:MOV R0, #0H
		RETI
		
		END