pir_and_buzzer.ino

#include "pitches.h"

int led = 13; //led pin
int inputPir = 2; //input pin for PIR sensor
int pirState = LOW; //no motion at start
int temp = 0; //variable for reading pin status

int melody[] = {NOTE_C4, NOTE_G3,NOTE_G3, NOTE_A3, NOTE_G3,0, NOTE_B3, NOTE_C4};

// note durations: 4 = quarter note, 8 = eighth note, etc.:
int noteDurations[] = {4, 8, 8, 4,4,4,4,4 };

void setup()
{
	pinMode(led, OUTPUT);
	pinMode(inputPir, INPUT);
	Serial.begin(9600);
}

void loop()//loop
{
	temp = digitalRead(inputPir); //read input PIR value
	if(temp == HIGH)
	{
		digitalWrite(led, HIGH); //turn LED on
		if (pirState == LOW)
		{
			song(); //play melody
			Serial.println("Motion Detected");
			pirState = HIGH;
		}
	}
	else
	{
		digitalWrite(led, LOW); //turn LED off
		if(pirState==HIGH)
		{
			Serial.println("Motion Ended");
			pirState=LOW;
		}
	}
}

//from arduino library
void song()
{
  // iterate over the notes of the melody:
  for (int thisNote = 0; thisNote < 8; thisNote++) {

    // to calculate the note duration, take one second 
    // divided by the note type.
    //e.g. quarter note = 1000 / 4, eighth note = 1000/8, etc.
    int noteDuration = 1000/noteDurations[thisNote];
    tone(8, melody[thisNote],noteDuration);

    // to distinguish the notes, set a minimum time between them.
    // the note's duration + 30% seems to work well:
    int pauseBetweenNotes = noteDuration * 1.30;
    delay(pauseBetweenNotes);
    // stop the tone playing:
    noTone(8);
  }
}