16C55 den 16F870'e dönüşüm

[ipek]

net'te hoş bir dosya buldum,pahalı 74C922,3,5 tipi keyboard entegreleri emule ediyor,azcık uğraştım,sanki çalışacak gibi oldu fakat sonucu çıkış portuna aktaramadım,
16F87x comparator barındırmıyor,dikkate almadım
ADCON1'e 110 yükleyip tüm A Portunu digital yaptım
Ram bölgesini yeniledim,
organize adresini 0000 yaptım
kısacası anladığım kadarıyla elimden gelen değişiklikleri uyguladım.
her iki dosyanın Isis simulasyonu mevcut,
gözlemlediğim kadarı ile ASM ye sadece Z'den ve Kabil Atıcı hocamdan olumlu cevaplar gelmiş,diğer arkadaşlar ilk aklına gelen önerileri paylaşmışlar,
acelesi ve önemi yok bir yol gösterirseniz devam edeceğim,kolaylıklar dilerim

http://s2.dosya.tc/server2/0hxm1h/16C55_keyboard_controller.rar.html

http://s2.dosya.tc/server2/qqsfoo/74C925_16F870.rar.html



kusursuz çalışan artık bulunmayan 16C55'e ait dosya

LIST	P=16C55 ; N=38, C=132, R=DEC

	TITLE	"KEYPAD ENCODER/EMULATOR - ENCODER.ASM"

;****************************************************************************
;*                               Keypad Encoder/Emulator                 *
;*                     Copyright 1996 DTE MICRO SYSTEMS                     *
;*               For use on the DTE MULTI KEYPAD EMULATOR board             *
;*              Note: This requires a PIC16C55 with RC oscillator           *
;****************************************************************************

; Define the general registers and I/O port addresses

RTCC	EQU	01	; Real Time Clock/Counter register address
PC	EQU	02	; Program Counter address
STATUS	EQU	03	; Status register address
FSR	EQU	04	; File Select Register address
PORTA	EQU	05	; I/O Port A (lower 4 bits only available)
PORTB	EQU	06	; I/O Port B (all 8 bits available)
PORTC	EQU	07	; I/O Port C (all 8 bits available)


; Assign labels to programming constants used in PIC assembly language.
; These are used by all instructions which have a choice of destination
; register for the result of their operation, where 'd' can be 1 or 0.
; Doing this makes program listings more logical and easier to read.

W	EQU	0	; Destination register becomes 'W' (acc.)
F	EQU	1	; Destination register becomes 'F' (file)

; Assign labels to the various bit values of the STATUS register (03h)

CARRY	EQU	0	; carry bit
DCARRY	EQU	1	; digit carry bit
ZERO	EQU	2	; Zero bit
PDOWN	EQU	3	; power-down bit
WATDOG	EQU	4	; watchdog time-out bit


; Assign basic pin labels to the bit numbers for I/O port A.

RA0	EQU	00	; Port A I/O bit 0
RA1	EQU	01	; Port A I/O bit 1
RA2	EQU	02	; Port A I/O bit 2
RA3	EQU	03	; Port A I/O bit 3

; Assign basic pin labels to the bit numbers for I/O port B.

RB0	EQU	00	; Port B I/O bit 0
RB1	EQU	01	; Port B I/O bit 1
RB2	EQU	02	; Port B I/O bit 2
RB3	EQU	03	; Port B I/O bit 3
RB4	EQU	04	; Port B I/O bit 4
RB5	EQU	05	; Port B I/O bit 5
RB6	EQU	06	; Port B I/O bit 6
RB7	EQU	07	; Port B I/O bit 7

; Assign basic pin labels to the bit numbers for I/O port C.

RC0	EQU	00	; Port C I/O bit 0
RC1	EQU	01	; Port C I/O bit 1
RC2	EQU	02	; Port C I/O bit 2
RC3	EQU	03	; Port C I/O bit 3
RC4	EQU	04	; Port C I/O bit 4
RC5	EQU	05	; Port C I/O bit 5
RC6	EQU	06	; Port C I/O bit 6
RC7	EQU	07	; Port C I/O bit 7

; Assign labels to the various (RAM) data file registers used

	ORG	08		; Set base address for RAM

COUNT1	RES	1		; General purpose counter
IPBUFF	RES	1		; Input buffer status byte
LASKEY	RES	1		; Previous offset into lookup table
OFFSET	RES	1		; Current offset into lookup table
OPBUFF	RES	1		; Binary output code for RC0 to RC4
STROBE	RES	1		; Column strobe line value

; END OF EQUATES SECTION

;****************************************************************************

; Start of program memory area

	ORG	0000		; SET ORIGIN ADDRESS

;****************************************************************************

; Scan the Keypad and put the data in "IPBUFF".  If the value is the same
; as "LASKEY" then try scanning other buttons to allow 'n' key rollover.
; To protect against possible 'glitches' causing the DDRs to change states,
; the DDRs for port A and port B are constantly updated by this routine.

SCANKP
	CLRF	OPBUFF		; START WITH "OPBUFF" EMPTY
	CLRF	OFFSET		; RESET OFFSET COUNTER TO ZERO
	MOVLW	B'11111111'
	TRIS	PORTA		; SET PORT A FOR INPUT
	TRIS	PORTB		; INITIALLY SET PORT B FOR INPUT
	MOVWF	PORTB		; PRESET ALL PORT B LINES HIGH
	MOVLW	B'11111110'
	MOVWF	STROBE		; PREPARE COLUMN STROBE LINE
SCAN2
	MOVF	STROBE,W	; GET CURRENT STROBE VALUE IN 'W'
	MOVWF	PORTB		; PREPARE THE PORT LINES FIRST
	TRIS	PORTB		; NOW ENABLE THE OUTPUTS
	NOP
	NOP			; ALLOW I/O LINES TO STABILISE
	NOP
	MOVF	PORTA,W		; GET BUTTON PRESSED COLUMN DATA
	MOVWF	IPBUFF		; SAVE IT IN "IPBUFF"
	
; Now, starting from the top row of the column we have just sampled,
; check each button in turn to see if any of them was pressed.  After
; each test, incriment the "OFFSET" value to adjust the offset into
; the lookup table of binary output codes - used later.

	BTFSS	IPBUFF,RA0	; SKIP IF NOT THE TOP ROW
	GOTO	SCAN4		; OTHERWISE SORT IT OUT
	INCF	OFFSET		; ADD 1 TO LOOKUP TABLE OFFSET
	BTFSS	IPBUFF,RA1	; SKIP IF NOT THE 2nd ROW
	GOTO	SCAN4		; OTHERWISE SORT IT OUT
	INCF	OFFSET		; ADD 1 TO LOOKUP TABLE OFFSET
	BTFSS	IPBUFF,RA2	; SKIP IF NOT THE 3rd ROW
	GOTO	SCAN4		; OTHERWISE SORT IT OUT
	INCF	OFFSET		; ADD 1 TO LOOKUP TABLE OFFSET
	BTFSS	IPBUFF,RA3	; SKIP IF NOT THE BOTTOM ROW
	GOTO	SCAN4		; OTHERWISE SORT IT OUT
	INCF	OFFSET		; ADD 1 TO LOOKUP TABLE OFFSET

; No buttons were pressed in this particular column, but we need to
; check any remaining columns that have not yet been scanned.

SCAN3
	BSF	STATUS,CARRY	; SET THE CARRY FLAG
	RLF	STROBE		; PREPARE STROBE LINE FOR NEXT COLUMN
	BTFSC	STATUS,CARRY	; SKIP IF ALL COLUMNS COMPLETED
	GOTO	SCAN2		; ELSE GO BACK FOR THE NEXT COLUMN	

; All columns have been scanned, no buttons were found to be pressed.
; In this situation the "OFFSET" location contains 20h (32 decimal)
; and cannot be converted, so exit with "LASKEY" intact from last time.

	GOTO	CONVERT		; EXIT WITHOUT UPDATING "LASKEY"

; A button is pressed, and "OFFSET" holds the unique offset value for it
; (after keypad prioritisation, of course, ie, lowest column/row address).
; Set the Data Available 'DA' line high, and copy the value into "LASKEY".

SCAN4
	BSF	OPBUFF,RC6	; PREPARE 'DA' LINE HIGH IN "OPBUFF"
	MOVF	OFFSET,W	; GET CURRENT "OFFSET" VALUE
	MOVWF	LASKEY		; AND UPDATE "LASKEY" WITH IT

;****************************************************************************

; Convert the value in "LASKEY" into a binary code for output on port C.
; These codes can be modified to suit your own needs.  The characters on
; the right correspond to the keypad layout shown in Figure 2 of the text.

CONVERT
	BCF	STATUS,CARRY	; CLEAR THE CARRY FLAG
	MOVF	LASKEY,W	; GET OFFSET VALUE IN 'W'
	ADDWF	PC,F		; ADD IT TO THE PROGRAM COUNTER
	RETLW	H'00'		; CODE FOR 'F' BUTTON - RA0 to RB0
	RETLW	H'01'		; CODE FOR 'B' BUTTON - RA1 to RB0
	RETLW	H'02'		; CODE FOR '7' BUTTON - RA2 to RB0
	RETLW	H'03'		; CODE FOR '3' BUTTON - RA3 to RB0
	RETLW	H'04'		; CODE FOR 'E' BUTTON - RA0 to RB1
	RETLW	H'05'		; CODE FOR 'A' BUTTON - RA1 to RB1
	RETLW	H'06'		; CODE FOR '6' BUTTON - RA2 to RB1
	RETLW	H'07'		; CODE FOR '2' BUTTON - RA3 to RB1
	RETLW	H'08'		; CODE FOR 'D' BUTTON - RA0 to RB2
	RETLW	H'09'		; CODE FOR '9' BUTTON - RA1 to RB2
	RETLW	H'0A'		; CODE FOR '5' BUTTON - RA2 to RB2
	RETLW	H'0B'		; CODE FOR '1' BUTTON - RA3 to RB2
	RETLW	H'0C'		; CODE FOR 'C' BUTTON - RA0 to RB3
	RETLW	H'0D'		; CODE FOR '8' BUTTON - RA1 to RB3
	RETLW	H'0E'		; CODE FOR '4' BUTTON - RA2 to RB3
	RETLW	H'0F'		; CODE FOR '0' BUTTON - RA3 to RB3
	RETLW	H'10'		; CODE FOR 'X' BUTTON - RA0 to RB4
	RETLW	H'11'		; CODE FOR 'T' BUTTON - RA1 to RB4
	RETLW	H'12'		; CODE FOR 'P' BUTTON - RA2 to RB4
	RETLW	H'13'		; CODE FOR 'K' BUTTON - RA3 to RB4
	RETLW	H'14'		; CODE FOR 'W' BUTTON - RA0 to RB5
	RETLW	H'15'		; CODE FOR 'S' BUTTON - RA1 to RB5
	RETLW	H'16'		; CODE FOR 'N' BUTTON - RA2 to RB5
	RETLW	H'17'		; CODE FOR 'J' BUTTON - RA3 to RB5
	RETLW	H'18'		; CODE FOR 'V' BUTTON - RA0 to RB6
	RETLW	H'19'		; CODE FOR 'R' BUTTON - RA1 to RB6
	RETLW	H'1A'		; CODE FOR 'M' BUTTON - RA2 to RB6
	RETLW	H'1B'		; CODE FOR 'H' BUTTON - RA3 to RB6
	RETLW	H'1C'		; CODE FOR 'U' BUTTON - RA0 to RB7
	RETLW	H'1D'		; CODE FOR 'Q' BUTTON - RA1 to RB7
	RETLW	H'1E'		; CODE FOR 'L' BUTTON - RA2 to RB7
	RETLW	H'1F'		; CODE FOR 'G' BUTTON - RA3 to RB7

;****************************************************************************

; Sort out the I/O signals and binary output code required on port C.
; Location "OPBUFF" holds the binary code for keypad data, plus the 'DA'
; bit status for RC6.  Port lines RC0 to RC4 must only be set for output
; if the OE input on RC5 is low, otherwise they must be set as inputs.

OUTPUT
	MOVF	OPBUFF,W	; GET BINARY OUTPUT VALUE
	MOVWF	PORTC		; PREPARE PORT C BEFORE ENABLING IT
	MOVLW	B'10111111'	; INITIALLY SET JUST RC6 FOR OUTPUT
	BTFSS	PORTC,RC5	; SKIP IF 'RC5' IS HIGH
	MOVLW	B'10100000'	; ELSE USE KEYPAD CODE TOO
	TRIS	PORTC		; ENABLE THE OUTPUTS

; Add a short switch debounce period to the whole process.  This
; will compensate for any worn or 'iffy' contacts on the keypad.

DBOUNC
	DECFSZ	COUNT1		; WAIT ...
	GOTO	DBOUNC
	RETLW	0		; FINISHED - RETURN

;****************************************************************************

; Beginning of the main program (program entry point)

START
	MOVLW	B'00000000'
	MOVWF	PORTC		; PREPARE ALL PORT C LINES LOW
	MOVLW	B'10111111'
	TRIS	PORTC		; INITIALLY SET JUST RC6 FOR OUTPUT
	MOVLW	H'20'
	CLRF	COUNT1		; CLEAR KEYPAD DEBOUNCE TIMER
	CLRF	LASKEY		; SET "LASKEY" TO ZERO

;****************************************************************************

COMMAND
	CALL	SCANKP		; SCAN THE KEYPAD MATRIX
	BCF	STATUS,CARRY	; CLEAR THE CARRY FLAG
	ADDWF	OPBUFF,F	; ADD CONVERTED CODE TO "OPBUFF"
	CALL	OUTPUT		; SORT OUT THE OUTPUT CODE
	GOTO	COMMAND		; DO IT FOREVER

;****************************************************************************

; Set up the reset vector for the type of processor used.
; This varies between devices but is at 1FFh on the 16C55

	ORG	H'1FF'
	GOTO	START
ZZZ				; END OF PROGRAM MARKER
	END

buda benim kuşa çevirdiğim 16F870'e çevirdiğim dosya...

#include p16f870.inc

; Assign basic pin labels to the bit numbers for I/O port A.
 __CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_ON & _XT_OSC & _LVP_OFF & _CPD_OFF
 Errorlevel ,-302 ,-305

 LIST	P=16F870, N=38, C=132, R=DEC


; Assign labels to the various bit values of the STATUS register (03h)

CARRY	EQU	0	; carry bit


; Assign basic pin labels to the bit numbers for I/O port A.

RA0	EQU	00	; Port A I/O bit 0
RA1	EQU	01	; Port A I/O bit 1
RA2	EQU	02	; Port A I/O bit 2
RA3	EQU	03	; Port A I/O bit 3

; Assign basic pin labels to the bit numbers for I/O port B.

RB0	EQU	00	; Port B I/O bit 0
RB1	EQU	01	; Port B I/O bit 1
RB2	EQU	02	; Port B I/O bit 2
RB3	EQU	03	; Port B I/O bit 3
RB4	EQU	04	; Port B I/O bit 4
RB5	EQU	05	; Port B I/O bit 5
RB6	EQU	06	; Port B I/O bit 6
RB7	EQU	07	; Port B I/O bit 7

; Assign basic pin labels to the bit numbers for I/O port C.

RC0	EQU	00	; Port C I/O bit 0
RC1	EQU	01	; Port C I/O bit 1
RC2	EQU	02	; Port C I/O bit 2
RC3	EQU	03	; Port C I/O bit 3
RC4	EQU	04	; Port C I/O bit 4
RC5	EQU	05	; Port C I/O bit 5
RC6	EQU	06	; Port C I/O bit 6
RC7	EQU	07	; Port C I/O bit 7

; Assign labels to the various (RAM) data file registers used

;;	ORG	20		; Set base address for RAM 8
  CBLOCK	0x20	; Set base address for RAM
COUNT1			; General purpose counter
IPBUFF			; Input buffer status byte
LASKEY			; Previous offset into lookup table
OFFSET			; Current offset into lookup table
OPBUFF			; Binary output code for RC0 to RC4
STROBE			; Column strobe line value
 ENDC

; END OF EQUATES SECTION



; Start of program memory area

	ORG	0000		; SET ORIGIN ADDRESS

;;START

; INITIALISE PORTS

	BSF	STATUS,5
	movlw b'00001111'       ; 
	movwf TRISA
	movlw b'00000000'		; 
	movwf TRISB
	movlw b'10100000'		; 
	movwf TRISC

;	MOVLW	B'00000000'
;	MOVWF	PORTC		; PREPARE ALL PORT C LINES LOW
;	MOVLW	B'10111111'
;	TRIS	PORTC		; INITIALLY SET JUST RC6 FOR OUTPUT
;	MOVLW	H'20'


;---------------------------------------------------------
	movlw b'00000110' ; All analog pins = digital
	movwf ADCON1	; 16F870'te comparator yok CMCON 7 de gerek yok
;----------------------------------------------------------

	bcf STATUS,RP0  ; back to RAM page 0






;;	MOVLW	H'20'
	CLRF	COUNT1		; CLEAR KEYPAD DEBOUNCE TIMER
	CLRF	LASKEY		; SET "LASKEY" TO ZERO


;****************************************************************************

; Start of program memory area
START


;;	ORG	0000		; SET ORIGIN ADDRESS



;****************************************************************************

COMMAND
	CALL	SCANKP		; SCAN THE KEYPAD MATRIX
	BCF	STATUS,CARRY	; CLEAR THE CARRY FLAG
	ADDWF	OPBUFF,F	; ADD CONVERTED CODE TO "OPBUFF"
	CALL	OUTPUT		; SORT OUT THE OUTPUT CODE
	GOTO	COMMAND		; DO IT FOREVER

;****************************************************************************

;****************************************************************************

; Scan the Keypad and put the data in "IPBUFF".  If the value is the same
; as "LASKEY" then try scanning other buttons to allow 'n' key rollover.
; To protect against possible 'glitches' causing the DDRs to change states,
; the DDRs for port A and port B are constantly updated by this routine.

SCANKP
	CLRF	OPBUFF		; START WITH "OPBUFF" EMPTY
	CLRF	OFFSET		; RESET OFFSET COUNTER TO ZERO
	MOVLW	B'00001111'	;11111111
;;	TRIS	PORTA		; SET PORT A FOR INPUT
	MOVWF	TRISA
;;	TRIS	PORTB		; INITIALLY SET PORT B FOR INPUT
	MOVWF	TRISB
	MOVWF	PORTB		; PRESET ALL PORT B LINES HIGH
	MOVLW	B'11111110'
	MOVWF	STROBE		; PREPARE COLUMN STROBE LINE
SCAN2
	MOVF	STROBE,W	; GET CURRENT STROBE VALUE IN 'W'
	MOVWF	PORTB		; PREPARE THE PORT LINES FIRST
;;	TRIS	PORTB		; NOW ENABLE THE OUTPUTS
	MOVWF   TRISB
	NOP
	NOP			; ALLOW I/O LINES TO STABILISE
	NOP
	MOVF	PORTA,W		; GET BUTTON PRESSED COLUMN DATA
	MOVWF	IPBUFF		; SAVE IT IN "IPBUFF"
	
; Now, starting from the top row of the column we have just sampled,
; check each button in turn to see if any of them was pressed.  After
; each test, incriment the "OFFSET" value to adjust the offset into
; the lookup table of binary output codes - used later.

	BTFSS	IPBUFF,RA0	; SKIP IF NOT THE TOP ROW
	GOTO	SCAN4		; OTHERWISE SORT IT OUT
	INCF	OFFSET		; ADD 1 TO LOOKUP TABLE OFFSET
	BTFSS	IPBUFF,RA1	; SKIP IF NOT THE 2nd ROW
	GOTO	SCAN4		; OTHERWISE SORT IT OUT
	INCF	OFFSET		; ADD 1 TO LOOKUP TABLE OFFSET
	BTFSS	IPBUFF,RA2	; SKIP IF NOT THE 3rd ROW
	GOTO	SCAN4		; OTHERWISE SORT IT OUT
	INCF	OFFSET		; ADD 1 TO LOOKUP TABLE OFFSET
	BTFSS	IPBUFF,RA3	; SKIP IF NOT THE BOTTOM ROW
	GOTO	SCAN4		; OTHERWISE SORT IT OUT
	INCF	OFFSET		; ADD 1 TO LOOKUP TABLE OFFSET

; No buttons were pressed in this particular column, but we need to
; check any remaining columns that have not yet been scanned.

SCAN3
	BSF	STATUS,CARRY	; SET THE CARRY FLAG
	RLF	STROBE		; PREPARE STROBE LINE FOR NEXT COLUMN
	BTFSC	STATUS,CARRY	; SKIP IF ALL COLUMNS COMPLETED
	GOTO	SCAN2		; ELSE GO BACK FOR THE NEXT COLUMN	

; All columns have been scanned, no buttons were found to be pressed.
; In this situation the "OFFSET" location contains 20h (32 decimal)
; and cannot be converted, so exit with "LASKEY" intact from last time.

	GOTO	CONVERT		; EXIT WITHOUT UPDATING "LASKEY"

; A button is pressed, and "OFFSET" holds the unique offset value for it
; (after keypad prioritisation, of course, ie, lowest column/row address).
; Set the Data Available 'DA' line high, and copy the value into "LASKEY".

SCAN4
	BSF	OPBUFF,RC6	; PREPARE 'DA' LINE HIGH IN "OPBUFF"
	MOVF	OFFSET,W	; GET CURRENT "OFFSET" VALUE
	MOVWF	LASKEY		; AND UPDATE "LASKEY" WITH IT

;****************************************************************************

; Convert the value in "LASKEY" into a binary code for output on port C.
; These codes can be modified to suit your own needs.  The characters on
; the right correspond to the keypad layout shown in Figure 2 of the text.

CONVERT
	BCF	STATUS,CARRY	; CLEAR THE CARRY FLAG
	MOVF	LASKEY,W	; GET OFFSET VALUE IN 'W'
	ADDWF	PCL,F		; ADD IT TO THE PROGRAM COUNTER
	RETLW	H'00'		; CODE FOR 'F' BUTTON - RA0 to RB0
	RETLW	H'01'		; CODE FOR 'B' BUTTON - RA1 to RB0
	RETLW	H'02'		; CODE FOR '7' BUTTON - RA2 to RB0
	RETLW	H'03'		; CODE FOR '3' BUTTON - RA3 to RB0
	RETLW	H'04'		; CODE FOR 'E' BUTTON - RA0 to RB1
	RETLW	H'05'		; CODE FOR 'A' BUTTON - RA1 to RB1
	RETLW	H'06'		; CODE FOR '6' BUTTON - RA2 to RB1
	RETLW	H'07'		; CODE FOR '2' BUTTON - RA3 to RB1
	RETLW	H'08'		; CODE FOR 'D' BUTTON - RA0 to RB2
	RETLW	H'09'		; CODE FOR '9' BUTTON - RA1 to RB2
	RETLW	H'0A'		; CODE FOR '5' BUTTON - RA2 to RB2
	RETLW	H'0B'		; CODE FOR '1' BUTTON - RA3 to RB2
	RETLW	H'0C'		; CODE FOR 'C' BUTTON - RA0 to RB3
	RETLW	H'0D'		; CODE FOR '8' BUTTON - RA1 to RB3
	RETLW	H'0E'		; CODE FOR '4' BUTTON - RA2 to RB3
	RETLW	H'0F'		; CODE FOR '0' BUTTON - RA3 to RB3
	RETLW	H'10'		; CODE FOR 'X' BUTTON - RA0 to RB4
	RETLW	H'11'		; CODE FOR 'T' BUTTON - RA1 to RB4
	RETLW	H'12'		; CODE FOR 'P' BUTTON - RA2 to RB4
	RETLW	H'13'		; CODE FOR 'K' BUTTON - RA3 to RB4
	RETLW	H'14'		; CODE FOR 'W' BUTTON - RA0 to RB5
	RETLW	H'15'		; CODE FOR 'S' BUTTON - RA1 to RB5
	RETLW	H'16'		; CODE FOR 'N' BUTTON - RA2 to RB5
	RETLW	H'17'		; CODE FOR 'J' BUTTON - RA3 to RB5
	RETLW	H'18'		; CODE FOR 'V' BUTTON - RA0 to RB6
	RETLW	H'19'		; CODE FOR 'R' BUTTON - RA1 to RB6
	RETLW	H'1A'		; CODE FOR 'M' BUTTON - RA2 to RB6
	RETLW	H'1B'		; CODE FOR 'H' BUTTON - RA3 to RB6
	RETLW	H'1C'		; CODE FOR 'U' BUTTON - RA0 to RB7
	RETLW	H'1D'		; CODE FOR 'Q' BUTTON - RA1 to RB7
	RETLW	H'1E'		; CODE FOR 'L' BUTTON - RA2 to RB7
	RETLW	H'1F'		; CODE FOR 'G' BUTTON - RA3 to RB7

;****************************************************************************

; Sort out the I/O signals and binary output code required on port C.
; Location "OPBUFF" holds the binary code for keypad data, plus the 'DA'
; bit status for RC6.  Port lines RC0 to RC4 must only be set for output
; if the OE input on RC5 is low, otherwise they must be set as inputs.

OUTPUT
	MOVF	OPBUFF,W	; GET BINARY OUTPUT VALUE
	MOVWF	PORTC		; PREPARE PORT C BEFORE ENABLING IT
	MOVLW	B'10111111'	; INITIALLY SET JUST RC6 FOR OUTPUT
	BTFSS	PORTC,RC5	; SKIP IF 'RC5' IS HIGH
	MOVLW	B'10100000'	; ELSE USE KEYPAD CODE TOO
;;	TRIS	PORTC		; ENABLE THE OUTPUTS
	MOVWF 	TRISC		;*********************************************
; Add a short switch debounce period to the whole process.  This
; will compensate for any worn or 'iffy' contacts on the keypad.

DBOUNC
	DECFSZ	COUNT1		; WAIT ...
	GOTO	DBOUNC
;;	RETLW	0		; FINISHED - RETURN
	RETURN
;****************************************************************************

; Beginning of the main program (program entry point)






	GOTO	START

	END