;   I have released this source code as open source.  Copy, modify, borrow, steal, I dont care
;   If you DO happen to use it somewhere, credit would be nice but dont feel any obligation.
;   There are absolutely no warranties either implied or expressed.

;  This code is for the pic12c508a

	list	p=12c508, r=dec

;------CPU EQUATES---------------------------------------------------------
; all the equates below are boiler plate code.

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

INDF                         EQU     H'0000'
TMR0                         EQU     H'0001'
PCL                          EQU     H'0002'
STATUS                       EQU     H'0003'
FSR                          EQU     H'0004'
OSCCAL                       EQU     H'0005'
GPIO                         EQU     H'0006'

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

GPWUF                        EQU     H'0007'
PA0                          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'

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

NOT_GPWU                     EQU     H'0007'
NOT_GPPU                     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'

;----- OSCCAL Bits --------------------------------------------------------

OSCFST                       EQU     H'0003'
OSCSLW                       EQU     H'0002'

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

        __MAXRAM H'1F'

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

_MCLRE_ON                    EQU     H'0FFF'
_MCLRE_OFF                   EQU     H'0FEF'
_CP_ON                       EQU     H'0FF7'
_CP_OFF                      EQU     H'0FFF'
_WDT_ON                      EQU     H'0FFF'
_WDT_OFF                     EQU     H'0FFB'
_LP_OSC                      EQU     H'0FFC'
_XT_OSC                      EQU     H'0FFD'
_IntRC_OSC                   EQU     H'0FFE'
_ExtRC_OSC                   EQU     H'0FFF'


	__CONFIG   _CP_OFF & _WDT_OFF & _MCLRE_OFF & _IntRC_OSC

;-------- PROGRAM START ---------------------------------------------------------

	;   set up the pins for i/o in the order that we need them to be.  This may be
	;   changed later depending on board layout.

ONTIME		equ	0x07
ONTIMETEMP	equ	0x08
OFFTIME		equ	0x09
OFFTIMETEMP	equ	0x0A

	org	0x00			;Effective Reset Vector
	goto	start

start
;   Initialize and setup the microcontroller.
	clrf	GPIO			;Clear I/O Port
	movlw	b'00001100'		;set the value in the working register to what the ouputs will be
	tris	GPIO			;Set PortB as output (yes, I DO know its deprecated)
	
;this is the startup routines

	movlw	b'11111111'
	movwf	GPIO	;set all the bits high so that we can see its doing something.

	movlw	b'00000000'	;and reset the timer.
	movwf	TMR0

;  Set up the internal timer

	;   None of this code will ever need to be changed.
	movlw	b'00010111'		;set up the option register, prescaler  = 256 and set up the weak pull ups.
	option				;set the option register

;------------------------------------------------------------------------------

	;set up the initial timer values

	movlw	b'00000001'
	movwf	ONTIME

	movlw	b'11111111'
	movwf	OFFTIME

	movf	ONTIME, 0
	movwf	ONTIMETEMP

	movf	OFFTIME, 0
	movwf	OFFTIMETEMP

loop
	
	movlw	b'11111111'
	movwf	GPIO
	movf	ONTIME, 0
	movwf	ONTIMETEMP

	;do the on time loop
ON	
	decfsz	ONTIMETEMP
	goto	ON

	movlw	b'00000000'
	movwf	GPIO
	movf	OFFTIME, 0
	movwf	OFFTIMETEMP

	;do the off time loop
OFF
	decfsz	OFFTIMETEMP
	goto	OFF


	;check to see if our timer has reached the predetermined time
	btfss	TMR0, 6
	goto	loop	

	movlw	b'00000000'
	movwf	TMR0

	btfsc	GPIO, 3 ;test pin 3 to see if they wanna shut the unit down.
	goto	UP

	btfsc	GPIO, 2
	goto	DOWN

	goto	loop

UP 

	decf	OFFTIME
	incf	ONTIME

	GOTO	loop

DOWN
	decf	ONTIME
        incfsz	OFFTIME

	GOTO loop

	end