external interrupt.asm

用到Proteus软件来仿真51单片机

LED		BIT		P1.0
LEDBUF	EQU		30H
		ORG		00H
		LJMP	START
		ORG		03H
		LJMP	INTERRUPT
START:	CLR		LEDBUF
		CLR		LED
		MOV		TCON,#01H	;外部中断0下降沿触发
		MOV		IE,#81H		;打开外部中断允许位（EX0）
							;及总中断允许位（EA）
		LJMP	$			;等待中断
INTERRUPT:
		PUSH	PSW			;保护现场
		CPL		LEDBUF		;取反LED
		MOV		C,LEDBUF
		MOV		LED,C
		POP		PSW			;恢复现场
		RETI
		END