/*
Created: 4th May 2018 5:21 PM
Author : Arif
Motion Sensor Alarm
Verion 4:

*/


// ATTINY13 pinout (partly)
// RESET PB5 ===|1   P   8|=== VCC
//      PB3 ===|2   I   7|=== PB2
//      PB4 ===|3   N   6|=== PB1
//      GND ===|4   S   5|=== PB0



#define F_CPU 1200000 // 1.2 Mhz default attiny13a

// for ease of coding
#define Triggered 1
#define NotTriggered 0
#define SensorHigh PINB&(1<<SensorPin)
#define SensorLow (PINB&(1<<SensorPin))==0
#define TRUE 1
#define FALSE 0


// Includes
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>

// Global Variables //
volatile unsigned long millis = 0;
unsigned long previousMillis =0;
const uint8_t buzzer = 3; /* Alarm Pin */
const uint8_t SensorPin = 4; /* Sensor Pins */


// FUNCTIONS
void timerSetup ();
void buzzing();


// Main Loop //
int main(void)
{
	//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//
	// SETUP
	//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//

	// RESET INTERRUPTS //
	// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ //
	cli(); // clear interrupts for safety
	// Set External Interrupt, must have to set i bit for interrupt library
	sei();
	// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ //

	// Initialize timer
	timerSetup ();



	// Pin Directions
	DDRB |= (1<<buzzer); // output
	DDRB &= ~(1<<SensorPin); // input


	// Startup Blink //
	PORTB |= (1<<buzzer);  _delay_ms(50);
	PORTB &= ~(1<<buzzer); _delay_ms(100);
	PORTB |= (1<<buzzer);  _delay_ms(50);
	PORTB &= ~(1<<buzzer); _delay_ms(100);

	// PIR Sensor's Initialization time 1 minute
	//_delay_ms(30000);
	//_delay_ms(30000);

	// sensor states
		uint16_t previousMillis =0 ;
	uint8_t SensorHits =0, edgeDetect =0, firsttime =0;


	//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//
	// LOOP
	//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//
	while (1)
	{
		// TRIGER CHECKING
		//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//
		if(SensorHigh) {
			edgeDetect = TRUE;
			PORTB |= (1<<buzzer);  _delay_ms(40);
			PORTB &= ~(1<<buzzer);
			PORTB |= (1<<buzzer);  _delay_ms(50);
			PORTB &= ~(1<<buzzer);
			_delay_ms(2000); // wait for PIR beeping time to pass
		}

		else if(SensorLow){
			if (edgeDetect == TRUE) { // if previously on
				SensorHits = SensorHits + 1;
				edgeDetect = FALSE; // reset detection
				if (firsttime == 0){ // only work on first trigger
					previousMillis = millis;
					firsttime = 1;
				}
			}
		}

		// DECISION TIME
		//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//
		if (SensorHits >=2){
			//PORTB |= (1<<buzzer);  _delay_ms(100);
			//PORTB &= ~(1<<buzzer);
			// check if its in threshold time
			if ((millis - previousMillis) <= 20000){
				buzzing();
				SensorHits = 0;
				firsttime = 0;
				previousMillis = millis;
			}

			else{
				SensorHits = 0;
			}
		}

	} //end while loop
} // end main loop
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//



//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//
// TIMER SETUP
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//
void buzzing(){
	uint8_t buzzCount = 0;
	while (buzzCount <3) {
		buzzCount = buzzCount + 1;
		PORTB |= (1<<buzzer);  _delay_ms(200);
		PORTB &= ~(1<<buzzer); _delay_ms(200);
	}


}




//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//
// TIMER SETUP
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//
void timerSetup (){
	// select prescaler
	TCCR0B = (1<<CS01); // 8 prescaler
	// wave generation mode
	TCCR0A = (1<<WGM01);
	// to get approx 1 ms time
	OCR0A = 150;
	// setup interrupt for compare A
	TIMSK0 = (1<<OCIE0A);
}

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//
// TIMER Interrupt
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//
// timer 0 overflow interrupt
// Global Variables

ISR(TIM0_COMPA_vect){
	millis = millis + 1;
}