tangent

   #include "p18F4520.inc"

    CONFIG OSC = HS
    CONFIG PWRT = OFF
    CONFIG WDT = OFF
    CONFIG PBADEN = OFF
    CONFIG LVP = OFF
 ;Nedan följer ett grundprogram från boken sidan 468 för angentbord 12-4
D15mH	equ D'100'
D15mL	equ D'255'
COL	equ 0x08
DR15mH	equ 0x09
DR15mL	equ 0x0A

    org 0x000000
PORST GOTO MAIN
RESET_ISR   GOTO    MAIN
	    org	0x000008
HI_ISR	BTFSC	INTCON,RBIF
	BRA	RBIF_ISR
	RETFIE





MAIN	CLRF	TRISD
	BCF	INTCON2,RBPU
	MOVLW	0xF0
	MOVWF	TRISB
	MOVWF	PORTB
KEYOPEN	CPFSEQ	PORTB
	GOTO	KEYOPEN
	MOVLW	upper(KC0DE0)
	MOVWF	TBLPTRU
	MOVLW	high(KC0DE0)
	MOVWF	TBLPTRH
	BSF	INTCON,RBIE
	BSF	INTCON,GIE
LOOP	GOTO	LOOP

RBIF_ISR    CALL    DELAY
	    MOVFF   PORTB,COL
	    MOVLW   0xFE
	    MOVWF   PORTB
	    CPFSEQ  PORTB
	    BRA	    ROW0
	    MOVLW   0xFC
	    MOVWF   PORTB
	    CPFSEQ  PORTB
	    BRA	    ROW1
	    MOVLW   0xFB
	    MOVWF   PORTB
	    CPFSEQ  PORTB
	    BRA	    ROW2
	    MOVLW   0xF7
	    MOVWF   PORTB
	    CPFSEQ  PORTB
	    BRA	    ROW3
	    GOTO    BAD_RBIF

ROW0	MOVLW	low(KC0DE0)
	BRA	FIND
ROW1	MOVLW	low(KC0DE1)
	BRA	FIND
ROW2	MOVLW	low(KC0DE2)
	BRA	FIND
ROW3	MOVLW	low(KC0DE3)
	BRA	FIND

FIND	MOVWF	TBLPTR
	MOVLW	0xF0
	XORWF	COL
	SWAPF	COL,F

AGAIN	RRCF	COL
	BC	MATCH
	INCF	TBLPTRL
	BRA	AGAIN

MATCH	TBLRD*+
	MOVFF	TABLAT,PORTD

WAIT	MOVLW	0xF0
	MOVWF	PORTB
	CPFSEQ	PORTB
	BRA	WAIT
	BCF	INTCON,RBIF
	RETFIE

BAD_RBIF    MOVLW   0x00
	    GOTO    WAIT

DELAY:	MOVLW	D15mH
	MOVWF	DR15mH
D2:	MOVLW	D15mL
	MOVWF	DR15mL
D1:	DECF	DR15mL,F
	BNZ	D1
	DECF	DR15mH,F
	BNZ	D2
	RETURN

	org 0x12C
KC0DE0:	DB  '0', '1', '2', '3'
KC0DE1:	DB  '4', '5', '6', '7'
KC0DE2:	DB  '8', '9', 'A', 'B'
KC0DE3:	DB  'C', 'D', 'E', 'F'

	END