Đây là chương trình đếm số lần switch on từ 1 đến 9 hiển thị lên LED 7 đoạn,dùng ngắt ngoài RB0 và kỹ thuật bảng.
Code:
;========================================
;Auhor: NHH
;Date: 02/03/06
;Hardware: PIC16F877A ,Crystal 10MHz
;========================================
TITLE "Count button on by Interrupt RB0"
PROCESSOR PIC16f877A
INCLUDE<P16f877A.inc>
__CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_ON & _HS_OSC & _WRT_OFF & _CPD_OFF &_LVP_OFF
;========================================
COUNT EQU 0x20
w_temp EQU 0x71 ; variable used for context saving
status_temp EQU 0x72 ; variable used for context saving
pclath_temp EQU 0x73 ; variable used for context saving
;=============================================================================
;CHUONG TRINH CHINH
;=============================================================================
ORG 0000h
GOTO MAIN
ORG 0004h
GOTO INTERRUPT
;==============================INTERRUPT PROGRAM===========================
INTERRUPT
movwf w_temp ; save off current W register contents
movf STATUS,w ; move status register into W register
movwf status_temp ; save off contents of STATUS register
movf PCLATH,w ; move pclath register into w register
movwf pclath_temp ; save off contents of PCLATH register
;******************************************************************************
BCF INTCON,INTF ;xoa co int
INCF COUNT,F
MOVLW d'10'
SUBWF COUNT,W
BTFSS STATUS,0
GOTO $+2
GOTO NODISPLAY
MOVF COUNT,W
CALL TABLE
MOVWF PORTD
retfie ; return from interrupt
NODISPLAY ;khong hien thi neu vuot qua 9
MOVLW d'10'
CALL TABLE
MOVWF PORTD
RETFIE
;******************************************************************************
movf pclath_temp,w ; retrieve copy of PCLATH register
movwf PCLATH ; restore pre-isr PCLATH register contents
movf status_temp,w ; retrieve copy of STATUS register
movwf STATUS ; restore pre-isr STATUS register contents
swapf w_temp,f
swapf w_temp,w ; restore pre-isr W register contents
retfie ; return from interrupt
;============== CHUONG TRINH CHINH===============
MAIN
BCF STATUS,RP1
BSF STATUS,RP0 ; chon BANK 1
MOVLW b'11111111' ;RB0=Input
MOVWF TRISB
CLRF TRISD
BCF OPTION_REG,INTEDG ;interrupt canh xuong
BCF STATUS,RP0 ; chon BANK 0
BSF INTCON,GIE ;cho phep interrupt toan cuc
BSF INTCON,INTE ;cho phep interrupt RB0
CLRF COUNT
MOVLW d'0'
CALL TABLE
MOVWF PORTD
GOTO $
;----------------------------------------------------------
; Bang tra ve Digital tu 0 den 9 va OFF
; Chi so dau truy cap la 0
; Bang o PAGE 0
ORG 0x80
TABLE
;----------------------------------------------------------
ADDWF PCL, F ; bat dau tai 0x80
RETLW b'00111111' ; 0
RETLW b'00000110' ; 1
RETLW b'01011011' ; 2
RETLW b'01001111' ; 3
RETLW b'01100110' ; 4
RETLW b'01101101' ; 5
RETLW b'01111101' ; 6
RETLW b'00000111' ; 7
RETLW b'01111111' ; 8
RETLW b'01101111' ; 9
RETLW b'00000000' ; OFF
END