PROGRAM K

;************************************
; written by :	John Morton			*
; date : 07/08/97				*
; version : 1.0					*
; file saved as : Alarm			*
; for PIC16F54				*
; clock frequency : 3.82 MHz		*
;************************************

; PROGRAM FUNCTION : An alarm system which can be set or disabled.

 		list 	     	P=16F54
		include	"c:\pic\p16f5x.inc"

		__config	_RC_OSC & _WDT_ON & _CP_OFF

;============
; Declarations :  

porta		equ		05
portb		equ		06
Post50		equ		08
Counter	equ		09
		
		org		1FF
		goto		Start
		org		0

;===========
; Subroutines : 

Init		clrf		porta		; resets inputs and outputs
		clrf		portb		;
		movlw		b'0011'	; RA0 : Sensor, RA1 :Settings switch,
		tris		porta		;   RA2 : not connected, RA3 : siren
		movlw		b'00000000' 	; RB0 : green LED, RB1 : red LED
		tris		portb		;   RB2-7 : not connected

		movlw		b'00001111'	; WDT prescaled by 128 (TMR0 not
		option				;   prescaled)

		clrf		Counter	; resets clock cycle counter
		movlw		dÕ50Õ		; sets up postscaler
		retlw		0

;=============
; Program Start : 

Start		call		Init		

Main		btfsc		porta, 1	; tests setting switch
		goto		GreenLed	; switch is high, so turn on green LED
		bsf		portb, 1	; switch is low, so turn on red LED

TenthSecond		
		decfsz		Counter	; has 1/10th second passed?
		goto		Continue	;
		decfsz		Post50		;
		goto		Continue	;
		clrf		portb		; it has, so turns off all LEDs

Continue	btfsc		porta, 1	; tests setting switch
		goto		Waste2Cycle	; disabled, so doesn't test trigger input

		btfss		porta, 0	; has motion sensor has been set?
		goto		TenthSecond	; not triggered, so loops back

		bsf		porta, 3	; turns on siren
EndLoop	clrwdt				; resets watchdog timer
		goto		EndLoop	; constantly loops
	
GreenLed	bsf		portb, 0	; turns on green LED
		goto		TenthSecond	; loops back to main body of program

Waste2Cycle	goto		TenthSecond	; wastes two clock cycles
	
		END