; proportional to integral ppm converter
; the device works as an integrator


	list	p=12F675
	radix	hex
	include P12F675.INC
	errorlevel -302 
	__CONFIG _CPD_OFF&_CP_OFF&_BODEN_OFF&_MCLRE_OFF&_WDT_OFF&_INTRC_OSC_NOCLKOUT

resetout	macro 	
		bcf		GPIO,	0x01;
		endm

setout		macro	
		bsf		GPIO,	0x01;
		endm

setstate0	macro	
		movlw	0xf0	;
		andwf	MYSTAT,	f	;
		bsf		mystat0		;
		endm

setstate1	macro	
		movlw	0xf0	;
		andwf	MYSTAT,	f	;
		bsf		mystat1		;
		endm

setstate2	macro	
		movlw	0xf0	;
		andwf	MYSTAT,	f	;
		bsf		mystat2		;
		endm

setstate3	macro	
		movlw	0xf0	;
		andwf	MYSTAT,	f	;
		bsf		mystat3		;
		endm

exitint	macro	
		goto	reti		;
		endm

prepare0	macro	
		resetout
		movlw	intv0		; intv0 is the state0 timeout
		movwf	TMR0
		bcf	INTCON,	T0IF	;
		endm

prepare1	macro	
		resetout
		movlw	intv1		; intv1 is the state1 timeout
		movwf	TMR0
		bcf	INTCON,	T0IF	;
		endm

prepare2	macro	
		setout
		movf	psout,	w		; psout is the state2 timeout
		movwf	TMR0			; aka the pulse out
		bcf	INTCON,	T0IF	;
		endm

prepare3	macro	
		resetout
		movlw	intv3		; intv0 is the state0 timeout
		movwf	TMR0
		bcf	INTCON,	T0IF	;
		endm

docalculus	macro
		movf	TMR0,	w	; load it
		movwf	psin		; to psin	
		
		movf	psin,	w	;
		addlw	th0			;
		btfss	STATUS,	C	; it should be some carry to carry on
		goto	exitc		; pulse too short
		
		movf	psin,	w	;
		addlw	th1			;
		btfss	STATUS,	C	; it should be some carry to carry on
		goto	calmin		; minimal pulse detected

		movf	psin,	w	;
		addlw	th2			;
		btfss	STATUS,	C	; it should be some carry to carry on
		goto	exitc		; pulse is neutral
		
		movf	psin,	w	;
		addlw	th3			;
		btfss	STATUS,	C	; it should be some carry to carry on
		goto	calmax		; maximal pulse detected
		
		goto	exitc		; pulse is too long
		
calmin	movlw	thmin		; test for minimal pulse (maximal couter0 value)
		addwf	psout,	w	; 
		btfss	STATUS,	C	;
		incf	psout,	f	; increment if the overflow was not generated			
		goto	exitc		;

calmax	movlw	thmax		; test for minimal pulse (maximal couter0 value)
		addwf	psout,	w	; 
		btfsc	STATUS,	C	;
		decf	psout,	f	; increment if the overflow was not generated			
		goto	exitc		;
		
exitc	nop;
		endm

; now file deffinitions
;*****constants


; HARDWARE

; GP0	in
; GP1	out
; GP2	
; GP3	i/o
; GP4	 
; GP5 	

; now file definitions

;CONSTANTS
intv0		equ	d'201'		; timeout state0, 7mS   
intv1		equ	d'238'		; -//- state1 2.3mS
intv3		equ	d'138'		; -//- state3 15mS
th0			equ d'10'		; too short inpulse th
th1			equ d'7'		; bandgap short
th2			equ d'5'		; bandgap long
th3			equ	d'2'		; too long th
thmax		equ d'240'		; maximal pulse out wdth
thmin		equ d'248'		; minimal -//-
psstart		equ d'244'		; startup value -//-
  
; the temporary files
W_TEMP		equ	0x20	; temporary w file
STATUS_TEMP	equ	0x21
PCLATH_TEMP	equ	0x22

; play files
MYSTAT		equ	0x23	; mystat
#define mystat0	MYSTAT, 0	; mystat0
#define mystat1	MYSTAT, 1	; mystat1
#define mystat2	MYSTAT, 2	; mystat2
#define mystat3	MYSTAT, 3	; mystat3

psin		equ	0x26	; input wdth
psout		equ	0x27	; output wdth

start	org	0x0000		; reset vector
 	nop					; allow debugger
	nop
	goto 	init		; goto initblock

; ISR XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

intr	org	0x0004		; interrupt vector
		MOVWF 	W_TEMP 		;copy W to temp register,could be in either bank
		SWAPF 	STATUS,	W 	;swap status to be saved into W
		BCF 	STATUS,	RP0 	;change to bank 0 regardless ofcurrent bank
		MOVWF 	STATUS_TEMP 	;save status to bank 0 register

		bcf	STATUS,	RP0
		bcf	STATUS, RP1

TM0T	btfss	INTCON,	T0IF	; timer0 interr test
		goto	notm			; if no timer0 interrupt
		bcf		INTCON,	T0IF	; clear it
		btfss	mystat2		
		goto	tmns2			; if no state 2
		prepare3				;
		setstate3
		exitint					;

tmns2	btfss	mystat1			;
		goto	tmns1			;
		prepare2				;
		setstate2				;
		exitint					;

tmns1	btfss	mystat3			;
		goto	tmns3			;
		prepare0				;
		setstate0				;
		exitint					;

tmns3	btfss	mystat0			;
		goto	tmns0			;
		prepare1				;
		setstate1				;
		exitint					;

tmns0	prepare2				;
		setstate2				;
		exitint					;

notm	btfss	INTCON,	GPIF	;
		goto	exitinti		;
		nop
		bcf		INTCON,	GPIF	; clear the int source
		movf	GPIO,	w		; read the port
		andlw 	0x01			; isolate lsb, in
		btfsc	STATUS,	Z		;
		goto	ntmin0			;
ntmin1	btfss	mystat0			;
		goto	exitinti		;
		prepare1				;
		setstate1				;
		exitint					;

ntmin0	btfss	mystat1			;
		goto	exitinti		;
		docalculus				;
		prepare2				;
		setstate2				;
		exitint					;

exitinti	exitint				;


reti	SWAPF 	STATUS_TEMP ,W	;swap STATUS_TEMP register into W, sets bank to original state
		MOVWF 	STATUS 		;move W into STATUS register
		SWAPF 	W_TEMP,	F 	;swap W_TEMP
		SWAPF W_TEMP,W 		;swap W_TEMP into W
	
		retfie			; exit general ISR



; INIT XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

init	bcf	INTCON,	GIE	; disable all interrupts

		bsf 	STATUS,	RP0 	; Bank 1
		call 	3FFh 		; Get the cal value
		movwf 	OSCCAL 		; Calibrate
		bcf 	STATUS,	RP0 	; Bank 0
	
		bcf	STATUS,	RP0	;
		bcf	STATUS,	RP1	; bank0
		clrf	GPIO		; clear port
		movlw	0x07		; all digital
		movwf	CMCON

		movlw	0x00			
		movwf	GPIO		;

		bsf	STATUS,	RP0	; bank1


dirset	movlw	b'11111101'	; all inputs but GP1
		movwf	TRISIO		; configure them

anaset	movlw	b'00000000'	; all digital 
		movwf	ANSEL		; 

		movlw	b'00000001'	; enable only gp0 IOCB
		movwf	IOCB		;

		bcf	STATUS,	RP0	; return to
		bcf	STATUS,	RP1	; bank0

		movlw	b'00000000'	; disable ADC, 
		movwf	ADCON0		;


		movlw	b'00101000'	; 
		movwf	INTCON		; enable TMR0 and IOCB
	
		bsf	STATUS,	RP0	; bank1
		movlw	b'00000000'	;
		movwf	PIE1		; 
		bcf	STATUS,	RP0	; return to
		bcf	STATUS,	RP1	; bank0
	
	movlw	b'00000000'	;
	movwf	T1CON		; timer, not enabled yet, no prescaler

	clrwdt 			;Clear WDT
	clrf	TMR0		;and tmr0

	bsf	STATUS,	RP0	; bank1
	movlw	b'01000110'	; 128x prescaler, to TMR0 as timer, GP2 positive interr
	movwf	OPTION_REG	; 
	movlw	b'00111100'	; WPU 
	movwf	WPU		;
	bcf	STATUS,	RP0	; return to
	bcf	STATUS,	RP1	; bank0
	
	movlw	0x01		;
	movwf	MYSTAT		;
	movlw	psstart		;
	movwf	psout		;


	bsf	INTCON,	GIE	; 
	
; the
mloop	goto	mloop		;
	


	org	0x3FF		;
	retlw	0x84		; the calibration value

	end