#include	<pic.h>
#include	<sys.h>

/*
 *	Doll house security system for the PIC 16C84
 */

#define	TOUT	0x10			// watchdog timeout bit in STATUS
#define	XTAL	2000000			// oscillator freq - about 2MHz (RC)
#define	PRE	4			// prescaler value
#define	RATE	2000			// 500uS per loop
#define	TICKS	50			// 50Hz tick timer
#define	GRACE	5			// 5 secs to open door after pressing bell
#define	PWROFF	120			// power off after this time of no activity

#define	DIVIDE	(XTAL/PRE/RATE/4)	// division ratio - must be < 256

typedef unsigned char	uchar;

/*
 *	Pin assignments
 *
 *	Port B
 *	0	Front door reed switch
 *	1	Interior light touch sensor
 *	2	Interior light control (0 = on)
 *	3	Speaker
 *	4	Party lights 1 (0 = on)
 *	5	Party lights 2
 *	6	Party lights 3
 *	7	Front door pushbutton
 *
 *	Port A is not used
 */

#define	PORTBIT(adr, bit)	((unsigned)(&adr)*8+(bit))

static bit	reed  @	PORTBIT(PORTB, 0);
static bit	touch @	PORTBIT(PORTB, 1);
static bit	light @	PORTBIT(PORTB, 2);
static bit	spkr  @	PORTBIT(PORTB, 3);
static bit	part0 @	PORTBIT(PORTB, 4);
static bit	part1 @	PORTBIT(PORTB, 5);
static bit	part2 @	PORTBIT(PORTB, 6);
static bit	bell  @	PORTBIT(PORTB, 7);

static bit	RTIF  @ PORTBIT(INTCON, 2);

static bit	alarm;		// alarm has been triggered
static bit	open;		// door already open
static bit	partying;	// lights-a-flashin'
static uchar	grace;		// period to open door
static uchar	ticktimer;	// tick timer
static uchar	sectimer;	// seconds timer
static uchar	altimer;	// alarm timer
static uchar	partytimer;
static uchar	flashtimer;	// flash timer
static uchar	powerdowntimer;

#define	IOBITS_B	0x83		// I/O bits specification

static unsigned  char	spkrcnt;	// speaker counter

/*
 *	The interrupt routine - the only interrupt source is the timer
 *	so we can assume it caused the interrupt
 */

void interrupt
timer(void)
{
	RTIF = 0;
	TMR0 = -DIVIDE;
	if(bell == 0) {
		powerdowntimer = 0;
		if(alarm) {
			alarm = 0;
			part0 = 1;
			part2 = 1;
		}
		grace = GRACE;
		++spkrcnt;
		spkrcnt &= 7;
		if(((spkrcnt+1) & spkrcnt) == 0)
			if(spkr)
				spkr = 0;
			else
				spkr = 1;

	} else
		partytimer = 0;
	if(alarm) {
		if(powerdowntimer >= 30) {
			alarm = 0;
			part0 = 1;
			part2 = 1;
		} else {
			++altimer;
			if(altimer & 0x80 || altimer & 1)
				if(spkr)
					spkr = 0;
				else
					spkr = 1;
			if(altimer & 0x80) {
				part0 = 1;
				part2 = 0;
			} else {
				part0 = 0;
				part2 = 1;
			}
		}
	}
	if(reed) {
		if(!open && !grace) {
			powerdowntimer = 0;
			alarm = 1;
		}
		open = 1;
		grace = 0;
	} else
		open = 0;
	if(++ticktimer == RATE/TICKS) {
		ticktimer = 0;
		if(++sectimer == TICKS) {
			powerdowntimer++;
			sectimer = 0;
			if(++partytimer == 2) {
				if(partying) {
					partying = 0;
					part0 = 1;
					part1 = 1;
					part2 = 1;
				} else {
					partying = 1;
					part0 = 0;
					part1 = 1;
					part2 = 1;
				}
			}
			if(grace)
				--grace;
		}
		if(partying && ++flashtimer == TICKS/4) {
			flashtimer = 0;
			if(part0 == 0) {
				part0 = 1;
				part1 = 0;
			} else if(part1 == 0) {
				part1 = 1;
				part2 = 0;
			} else {
				part0 = 0;
				part1 = 1;
				part2 = 1;
			}
		}
	}
}

main()
{
	for(;;) {
		OPTION = 1;
		TRISB = IOBITS_B;
		TRISA = 0x00;			// all bits outputs - lower current drain
		PORTA = 0xFF;
		PORTB = 0xF7;			// set bits high
		if(!(PORTB & 0x80))
			powerdowntimer = 0;
		INTCON = 0xA0;			// enable rtcc interrupt
		for(;;) {
			asm("clrwdt");
			if(powerdowntimer >= PWROFF) {
				INTCON = 0;
				PORTB = 0x74;
				TRISB = 0x0;	// all bits output - lower current drain
				OPTION = 0x8D;	// WDT prescaled by 64 - about 1200 ms
				asm("	sleep");
				break;
			}
		}
	}
}