;**********************************************************************
;*	convert 10 key input to 4 bit binary
;**********************************************************************

        list	P=PIC16F88
        #include <P16F88.INC>
	__CONFIG	_CONFIG1, _INTRC_IO &_CP_OFF & _WDT_OFF & _PWRTE_ON &_LVP_OFF & _MCLR_OFF & _CCP1_RB3
	__CONFIG    _CONFIG2, _IESO_OFF & _FCMEN_OFF
;***** VARIABLE DEFINITIONS
w_temp		EQU	0x0C        ; variable used for context saving 
status_temp	EQU	0x0D        ; variable used for context saving
tmp		EQU	0x0F
CNT0		EQU	0x20
CNT1		EQU	0x21
CNT2		EQU	0x22
CNT3		EQU	0x23
CNT4		EQU	0x24
w_temp0		EQU	0x25
w_temp1		EQU	0x26
w_temp2		EQU	0x27
w_temp3		EQU	0x28
w_temp4		EQU	0x29
daddr		EQU	0x2a

;***** EEPROM Setting
	org	0x2100
	DE	0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xb, 0xf, 0xf, 0xf, 0x9, 0xf, 0x6, 0x3, 0xf
	DE	0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0x0, 0xf, 0xf, 0xf, 0x8, 0xf, 0x5, 0x2, 0xf
	DE	0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xa, 0xf, 0xf, 0xf, 0x7, 0xf, 0x4, 0x1, 0xf

;**********************************************************************
;RESET_VECTOR	CODE	0x000		; processor reset vector
		org 0x000
  		goto    Init              ; go to beginning of program
		org	0x008


;ISR		CODE	0x004             ; interrupt vector location
;		goto	Interrupt	  ; go to the interrupt location

;MAIN_PROGRAM	CODE
;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    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

Init:
;***** PORT mode set *****
;RA0:3	binary out
;RB0:2	out(key pad 1-3 pin)
;RB3	out(Buzzer)
;RB4:7	in(key pad 4-7 pin)
;AN0:4  disable
;CCP1	disable

	BCF	INTCON,GIE	;Interrupt Disable
	BSF INTCON,RBIE	;PortB Interrupt Enable
	BSF	STATUS,RP0	;Set page 1
	CLRF	TRISA
	MOVLW	0xf0
	MOVWF	TRISB
	CLRF	ANSEL	; Analog input disable
	MOVLW	0x70	; set INTOSC to 8Mhz
	MOVWF	OSCCON
	BCF	STATUS,RP0	;Set page 0

;	CLRF	CCP1CON	; CCP1 disable
	MOVLW	0xff
	MOVWF	PORTA

;**** 
	CALL	Buzzer
	CALL	Sleep100ms
	CALL	Buzzer
	
Main:
	MOVLW	0xff
	MOVWF	PORTB
Row1:
	CLRF	daddr	; set 0 to high addr
	BCF	PORTB,0		; xxxx1110
	SWAPF	PORTB,W		; read port B and swap high and low
	BSF	PORTB,0		; xxxx1111
	ANDLW	0x0f		; get low addr
	ADDWF	daddr,F		; set low to ROM addr
	XORLW	0x0f		; if low addr == 1111(not push row1 key)
	BTFSS	STATUS,Z
	GOTO	Output_Data
Row2:
	MOVLW	0x10
	MOVWF	daddr	; set 1 to high addr
	BCF	PORTB,1		; xxxx1101
	SWAPF	PORTB,W		; read port B and swap high and low
	BSF	PORTB,1		; xxxx1111
	ANDLW	0x0f		; get low addr
	ADDWF	daddr,F		; set low to ROM addr
	XORLW	0x0f		; if low addr == 1111(not push row2 key)
	BTFSS	STATUS,Z
	GOTO	Output_Data
Row3:
	MOVLW	0x20
	MOVWF	daddr
	BCF	PORTB,2		; xxxx1011
	SWAPF	PORTB,W		; read port B and swap high and low
	BSF	PORTB,2		; xxxx1111
	ANDLW	0x0f		; get low addr
	ADDWF	daddr,F		; set low to ROM addr
	XORLW	0x0f		; if low addr == 1111(not push row3 key)
	BTFSs	STATUS,Z
	GOTO	Output_Data
No_Input:			; no keys pushed
	CALL	Sleep100ms
	MOVLW	0xff
	MOVWF	PORTA
	MOVLW	0x08
	MOVWF	PORTB
	BCF 	INTCON,RBIF
	SLEEP
	CALL	Buzzer
	GOTO	Main
Output_Data:
	MOVF	daddr,W
	BANKSEL	EEADR
	MOVWF	EEADR		; set ROM address
	BANKSEL EECON1
	BCF		EECON1,EEPGD
	BSF		EECON1,RD	; RD bit set
	BANKSEL	EEDATA
	MOVF	EEDATA,W	; read ROM data
	BANKSEL	PORTA		; set page0
	MOVWF	PORTA		; write ROM data to port A
	GOTO	Main

;***** Buzzer routines *****
; Buzzer connected to PortB:3
; 1kHz, 20 msec
Buzzer:
	MOVWF	w_temp4
	MOVLW	D'20'
	MOVWF	CNT4
RB3_Hi:	BCF		PORTB,3
	CALL	Sleep500us
	BSF		PORTB,3
	CALL	Sleep500us
	DECFSZ	CNT4, F
	GOTO	RB3_Hi
	MOVF	w_temp4, W
	RETURN

;***** sleep routines *****
Sleep1s:
	MOVWF	w_temp0
	MOVLW	D'10'
	MOVWF	CNT0
Loop0:	CALL	Sleep100ms
	DECFSZ	CNT0, F
	GOTO	Loop0
	MOVF	w_temp0, W
	RETURN

Sleep100ms:
	MOVWF	w_temp1
	MOVLW	D'199'
	MOVWF	CNT1
Loop1:	CALL	Sleep500us
	DECFSZ	CNT1, F
	GOTO	Loop1
	MOVF	w_temp1,W
	RETURN

Sleep500us:
	MOVWF	w_temp2
	MOVLW 	D'199'
	MOVWF	CNT2
Loop2:	NOP
	NOP
	DECFSZ	CNT2, F
	GOTO	Loop2
	MOVF	w_temp2,W
	RETURN

	END                     ; directive 'end of program'