代码

#include<p16f877.inc>
__CONFIG(_CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_ON & _XT_OSC & _WRT_OFF & _LVP_OFF& _CPD_OFF);

	cblock 0x20
microSec	:2
ms50
second
minute
hour
	endc

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

	org 0x0000
	goto	main
	org 0x0004
	;banksel w_temp
	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

	bcf 	INTCON,T0IF
	MOVLW	0X10
	ADDWF   microSec+1,f
	goto	EndOfInt

EndOfInt
	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 0x0100
main

	clrf	microSec
	clrf	microSec+1
	clrf	ms50
	clrf	second
	;clrf	minute
	
	clrf	hour
	banksel	OPTION_REG
	MOVLW	B'00000011'
	MOVWF	OPTION_REG
	CLRF	STATUS
	MOVLW 	0X20
	MOVWF	FSR
	
ClearBank0
	clrf	INDF
	incf	FSR,f
	btfss	FSR,7
	GOTO 	ClearBank0
	movlw	.50
	movwf	minute
	clrf	INTCON
	BSF		INTCON,T0IE
	BSF		INTCON,GIE
Loop
	clrwdt
	call 	ClockRun
	goto	Loop

ClockRun
	bcf		INTCON,T0IE
	BANKSEL	microSec
	movlw	0xb0
	addwf	microSec,f
	movlw	0x3c
	skpnc
	movlw	0x3d
	addwf	microSec+1,f
	skpnc
	goto	_msTimeout

	movlw	0x50
	addwf	microSec,f
	movlw	0xc3
	skpnc
	movlw	0xc4
	addwf	microSec+1,f
	goto	_clockExit

_msTimeout
	incf	ms50,f
	movlw	.20
	xorwf	ms50,w
	;xorwf	ms50,f
	skpz
	goto	_clockExit
	clrf	ms50
	incf	second,f
	movlw	.60
	xorwf	second,w
	;xorwf	second,f
	skpz
	goto	_clockExit
	clrf	second
	incf	minute,f
	movlw	.60
	xorwf	minute,w
	;xorwf	minute,f
	skpz
	goto	_clockExit
	clrf	minute
	incf	hour,f
	movlw	.24
	xorwf	hour,w
	;xorwf	hour,f
	skpnz
	clrf	hour

_clockExit
	bsf	INTCON,T0IE
	return

end

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