Code:
; 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.