代码

#include<p16f877.inc>

w_temp 		equ 0x30
status_temp	equ 0x31
pch_temp	equ 0x32
fsr_temp	equ	0x33


	org 0x000
	goto main

	org 0x004
	movwf	w_temp
	movf	STATUS,W
	CLRF	STATUS
	MOVWF	status_temp
	movf	PCLATH,W
	MOVWF	pch_temp
	movf	FSR,W
	MOVWF	fsr_temp
	clrf	PCLATH

	btfss	INTCON,T0IE
	GOTO	Int_Exit
	btfss	INTCON,T0IF
	GOTO	Int_Exit
	BCF		INTCON,T0IF
	BANKSEL	PORTB
	MOVLW	.1
	XORWF	PORTB,F
	GOTO	Int_Exit

Int_Exit
	clrf	STATUS
	MOVF	fsr_temp,w
	movwf	FSR
	MOVF	pch_temp
	movwf	PCLATH
	MOVF	status_temp,w
	movwf	STATUS
	SWAPF	w_temp,f
	SWAPF	w_temp,w
	RETFIE

	org 0x100
main
	banksel OPTION_REG
	MOVLW	B'00001000'
	MOVWF	OPTION_REG
	BANKSEL	INTCON
	CLRF	INTCON
	BSF		INTCON,T0IE
	BSF		INTCON,GIE
	banksel	TRISB
	movlw	0x00
	movwf	TRISB
Loop
	GOTO	Loop

end

仿真效果图

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