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;****************************************************************************************
PROCESSOR	P16F877A
INCLUDE 	<P16F877A.inc>
__CONFIG   	_CP_OFF	& _PWRTE_ON & _WDT_OFF & _HS_OSC & _LVP_OFF &_BODEN_OFF
;****************************************************************************************
	ORG		0X20
COUNT1		EQU		0X20
COUNT2		EQU		0X21
COUNT3		EQU		0X22
;****************************************************************************************
	ORG	0X0000
	GOTO	MAIN
;	ORG	0X0004
;	GOTO	INTERRUPT
;*****************************************************************************************
	ORG	0X0005
MAIN
	BCF	STATUS,RP1
	BSF	STATUS,RP0		;BANK1
	CLRF	TRISC			;PORTC IS OUTPUT
	BCF	STATUS,RP0		;BANK0
	CLRF	PORTC
	GOTO	C0
C0
	BSF	PORTC,0
	CALL	DELAY_LONG
	BCF	PORTC,0
	CALL	DELAY_LONG
C1
	BSF	PORTC,1
	CALL	DELAY_LONG
C2
	BSF	PORTC,2
	CALL	DELAY_LONG
	BCF	PORTC,2
	CALL	DELAY_LONG
	GOTO	C0

;*****************************************************************************************
DELAY_LONG
	MOVLW	D'5'
	MOVWF	COUNT3
DELAY_LONG_START
	DECFSZ 	COUNT3,F
	GOTO	$+2
	RETURN
	CALL	DELAY
	GOTO	DELAY_LONG_START
;******************************************************************************
DELAY
	MOVLW	D'255'
	MOVWF	COUNT1
LOOP1
	MOVLW	D'255'
	MOVWF	COUNT2
	DECFSZ	COUNT1,F
	GOTO	LOOP2
	RETURN
LOOP2
	DECFSZ	COUNT2,F
	GOTO	LOOP2
	GOTO	LOOP1

END

ĐOẠN CODE TRÊN EM VIẾT THỬ CHO PORTC, EM THẮC MẮC LÀ TẠI SAO BIT1 NÓ SÁNG RỒI TẮT.NHỜ MỌI NGƯỜI CHỈ HỘ.CẢM ƠN NHIỀU.