Capture Mode

[nguyen.geo]

;		PIC16F877A HOAT DONG O CHE DO CAPTURE MODE
;                        
WAIT	EQU		0x22
WAIT1	EQU		0x23
WAIT2	EQU		0x24
	include <p16f877a.inc>
	__CONFIG   _CP_OFF & _WDT_OFF & _PWRTE_ON & _XT_OSC	& _LVP_OFF
	org 0x000 
	CLRF   	    STATUS
;			DOAN CHUONG TRINH KHOI TAO CHO CAPTURE MODE
	BSF  		STATUS,RP0 
	BSF			TRISC,2 	;		RC2 IN-PUT CHON CHAN RC2 LAM CHAN DUA XUNG VAO
	CLRF		TRISB
	BCF  		STATUS,RP0 
	CLRF		CCP1CON		;		KHOI TAO CHO CHE DO CAPTURE MODE 
	MOVLW		.4			;		NAP GIA TRI TRUYEN VAO THANH GHI CCP1CON
	MOVWF		CCP1CON		;		CHI KIEM TRA SUON XUNG XUONG
									
	CLRF		T1CON		;		KHOI DONG CHO TIMER1
	BSF			T1CON,TMR1ON
Loop
	CLRF		CCPR1H		;		XOA THANH GHI CCPR1
	CLRF		CCPR1L
	BCF			PIR1,CCP1IF	;		XOA CO NGAT DE TIEP TUC.
	NOP
	BTFSS		PIR1,CCP1IF	;		DOI CCP1IF SET LEN 1
	GOTO		$-1
	MOVF		CCPR1H,0	;		DOC GIA TRI TU THANH GHI CCPR1L
	MOVWF		PORTB		;		HIEN THI RA PORTB
	CALL		DELAY
	MOVF		CCPR1L,0	;		DOC GIA TRI TU THANH GHI CCPR1L
	MOVWF		PORTB		;		HIEN THI RA PORTB
	CALL		DELAY
	GOTO 		Loop		;		LAP VO THOI HAN

DELAY		;		DOAN CHUONG TRINH TAO THOI GIAN TRE
	MOVLW		.250
	MOVWF		WAIT
D1	
	MOVLW		.250
	MOVWF		WAIT1
D2	
	MOVLW		.250
	MOVWF		WAIT2
	DECFSZ		WAIT2,1
	GOTO		$-1	
	DECFSZ		WAIT1,1
	GOTO		D2	
	DECFSZ		WAIT,1
	GOTO		D1	
	RETURN
	END

Em da thu phat xung vao chan RC2 tan so la 10KHz.nhung no khong chay va khong hieu la no sai o cho nao. cac anh giup em voi.