;	PIC16C61/71 demostration program
;	M P Roberts	12/1/97

        NOLIST

;==========================================================================
;
;       Verify Processor
;
;==========================================================================

        IFNDEF __16C71
           MESSG "Processor-header file mismatch.  Verify selected processor."
        ENDIF

;==========================================================================
;
;       Register Definitions
;
;==========================================================================

W                            EQU     H'0000'
F                            EQU     H'0001'

;----- Register Files------------------------------------------------------

INDF                         EQU     H'0000'
TMR0                         EQU     H'0001'
PCL                          EQU     H'0002'
STATUS                       EQU     H'0003'
FSR                          EQU     H'0004'
PORTA                        EQU     H'0005'
PORTB                        EQU     H'0006'
ADCON0                       EQU     H'0008'
ADRES                        EQU     H'0009'
PCLATH                       EQU     H'000A'
INTCON                       EQU     H'000B'

OPTION_REG                   EQU     H'0001'
TRISA                        EQU     H'0005'
TRISB                        EQU     H'0006'
ADCON1			     EQU     H'0008'

;----- STATUS Bits --------------------------------------------------------

IRP                          EQU     H'0007'
RP1                          EQU     H'0006'
RP0                          EQU     H'0005'
NOT_TO                       EQU     H'0004'
NOT_PD                       EQU     H'0003'
Z                            EQU     H'0002'
DC                           EQU     H'0001'
C                            EQU     H'0000'

;----- INTCON Bits --------------------------------------------------------

GIE                          EQU     H'0007'
ADIE                         EQU     H'0006'
T0IE                         EQU     H'0005'
INTE                         EQU     H'0004'
RBIE                         EQU     H'0003'
T0IF                         EQU     H'0002'
INTF                         EQU     H'0001'
RBIF                         EQU     H'0000'

;----- OPTION Bits --------------------------------------------------------

NOT_RBPU                     EQU     H'0007'
INTEDG                       EQU     H'0006'
T0CS                         EQU     H'0005'
T0SE                         EQU     H'0004'
PSA                          EQU     H'0003'
PS2                          EQU     H'0002'
PS1                          EQU     H'0001'
PS0                          EQU     H'0000'

;==========================================================================
;
;       RAM Definition
;
;==========================================================================

        __MAXRAM H'AF'
        __BADRAM H'07', H'30'-H'7F', H'87'

;==========================================================================
;
;       Configuration Bits
;
;==========================================================================

_CP_ON                       EQU     H'3FEF'
_CP_OFF                      EQU     H'3FFF'
_PWRTE_ON                    EQU     H'3FFF'
_PWRTE_OFF                   EQU     H'3FF7'
_WDT_ON                      EQU     H'3FFF'
_WDT_OFF                     EQU     H'3FFB'
_LP_OSC                      EQU     H'3FFC'
_XT_OSC                      EQU     H'3FFD'
_HS_OSC                      EQU     H'3FFE'
_RC_OSC                      EQU     H'3FFF'

        LIST    ; PIC16C71 is the target processor

	__CONFIG _CP_OFF & _PWRTE_ON & _WDT_OFF & _XT_OSC

	;  data register definitions
temp	equ	h'C'	;temporary register
temp2	equ	h'D'	;temporary register
cnt	equ	h'E'	;serial bit counter
csec	equ	h'F'	;1/100 second counter

serpin	equ	h'2'	;serial output pin on PORTA

	org	0
	goto	Start

	org	4			;interrupt routine
	bcf	INTCON,T0IF		;clear interrupt flag
					;your code here
	movlw	h'80'
	call	COUT		;Display RAM address to 0
	movlw	'H'
	call	DOUT
	movlw	'e'
	call	DOUT
	movlw	'l'
	call	DOUT
	movlw	'l'
	call	DOUT
	movlw	'o'
	call	DOUT
	movlw	' '
	call	DOUT
	movlw	'F'
	call	DOUT
	movlw	'r'
	call	DOUT
	movlw	'e'
	call	DOUT
	movlw	'd'
	call	DOUT

	incf	csec,F	;increment seconds counter
	movlw	d'100'
	subwf	csec,0	;w=csec-100
	btfsc	STATUS,Z	;skip if csec<>100
	clrf	csec	;reset csec=0

	movf	csec,F		
	btfsc	STATUS,Z	;skip if csec <>0
	call	HELLO
	decf	csec,W	;w=csec-1
	btfsc	STATUS,Z	;skip if csec <>1
	call	FRED

	retfie		;return from interrupt


HELLO	movlw	'H'
	call	SERIAL
	movlw	'e'
	call	SERIAL
	movlw	'l'
	call	SERIAL
	movlw	'l'
	call	SERIAL
	movlw	'o'
	call	SERIAL
	return

FRED	movlw	' '
	call	SERIAL
	movlw	'F'
	call	SERIAL
	movlw	'r'
	call	SERIAL
	movlw	'e'
	call	SERIAL
	movlw	'd'
	call	SERIAL
	return




	;  start of main programme
	;  set up system

Start	bcf	STATUS,RP0	;bank 0	
	movlw	b'10100000'
	movwf	INTCON		;interupts from TMR0 only
	clrf	PORTB		;port b all off
	clrf	PORTA		;port a all off
	bsf	STATUS,RP0	;bank 1
	movlw	b'00000100'
	movwf	OPTION_REG	;set option, pulup, /32 clk
	clrf	TRISB		;portb all output
	movlw	b'00000011'
	movwf	ADCON1		;porta digital only
	movlw	b'00011000'
	movwf	TRISA		;porta bits0-2 out 3,4,in
	bcf	STATUS,RP0	;bank 0	

	clrf	csec		;seconds counter to 0

	;  set up display
	movlw	h'38'		
	call	COUT		;2 lines

	clrf	temp2
	movlw	d'6'		;delay for 4100us
	movwf	temp
st1	decfsz	temp2,F
	goto	st1
	decfsz	temp,F
	goto	st1

	movlw	h'38'		
	call	COUT		;2 lines

	movlw	d'20'		;delay for 60us
	movwf	temp
st2	decfsz	temp,F
	goto	st2

	movlw	h'38'		
	call	COUT		;2 lines
	movlw	h'38'		
	call	COUT		;2 lines

	movlw	h'06'
	call	COUT		;entry mode cursor right
	movlw	h'0C'		
	call	COUT		;display on,no cursor,no blink
	movlw	h'01'		
	call	COUT		;clear + address 0
	;  wait 1600uS (not needed wait interrupt)	
	clrf	temp2		
	movlw	d'2'		;delay for 1600us
	movwf	temp
st3	decfsz	temp2,F
	goto	st3			;3 x256 =768
	decfsz	temp,F
	goto	st3


	;  operating loop

loop	nop
	goto	loop


	;  display output subroutines

COUT	bcf	PORTA,0	;RA0=0 control data for display
	goto	out1
DOUT	bsf	PORTA,0	;RA0=1 data to display
out1	movwf	PORTB	;portb=w
	bsf	PORTA,1	;enable
	bcf	PORTA,1	;disable
			;  wait > 40uS
	movlw	d'13'	;w=13
	movwf	temp	;temp=13
out2	decfsz	temp,F	;dec skip zero
	goto out2
	return

	;sub to output w as serial info
SERIAL	movwf	temp		;temp=w
	movlw	8
	movwf	cnt		;cnt=8
	bcf	PORTA,serpin	;start bit
	goto	ser1
ser1	call	SDEL
	rrf	temp,F
	btfsc	STATUS,C
	bsf	PORTA,serpin
	btfss	STATUS,C
	bcf	PORTA,serpin
	decfsz	cnt,F
	goto	ser1
	goto	ser2
ser2	call	SDEL
	bsf	PORTA,serpin	;stop bit
	call	SDEL
	call	SDEL
	return


	;delay for serial(3.2768/4/9600)
SDEL	movlw	d'24'
	movwf	temp2
sdel1	decfsz	temp2,F
	goto	sdel1
	return



	END