Arduino Motion Sensing Alarm

This instructable will show how to make a functioning motion sensing alarm with an arduino uno.

The materials needed for this are:

1 Arduino Uno

1 PIR Motion Sensor

1 LED

1 Piezo Buzzer

1 Breadboard

1 Jumper Wires

A computer 

The pir sensor has 3 pins

The first on the left must be connected to a GND pin

The one in the middle must be connected to a digital pin(2)

The one on the right must be connected to a 5v pin

The piezo buzzer has 2 pins

One has to connect to a GND

The other has to connect to a digital pin

The LED has two pins, the ANODE and the CATHODE

The Anode is longer and is always wired to positive voltage

The Cathode is shorter and always wired to negative voltage

Wire the Anode to pin 13

Wire the Cathode to the GND pin next to it

int ledPin = 13;         

int inputPin = 2;        

int pirState = LOW;       

int val = 0;          

int pinSpeaker = 10;      

void setup() {

 pinMode(ledPin, OUTPUT);    

 pinMode(inputPin, INPUT);   

 pinMode(pinSpeaker, OUTPUT);

 Serial.begin(9600);

}

void loop(){

 val = digitalRead(inputPin); 

 if (val == HIGH) {      

  digitalWrite(ledPin, HIGH);  

  playTone(300, 160);

  delay(150);

  if (pirState == LOW) {

   Serial.println("Motion detected!");

   pirState = HIGH;

  }

 } else {

   digitalWrite(ledPin, LOW); 

   playTone(0, 0);

   delay(300);   

   if (pirState == HIGH){

   Serial.println("Motion ended!");

   pirState = LOW;

  }

 }

}

void playTone(long duration, int freq) {

  duration *= 1000;

  int period = (1.0 / freq) * 1000000;

  long elapsed_time = 0;

  while (elapsed_time < duration) {

    digitalWrite(pinSpeaker,HIGH);

    delayMicroseconds(period / 2);

    digitalWrite(pinSpeaker, LOW);

    delayMicroseconds(period / 2);

    elapsed_time += (period);

  }

}

During making this instructable I struggled a lot because I couldn't even make the arduino. After days of working on both the code and the wiring I finally got it correct and learned a lot a bout debugging codes. I learned where I have to put indents and how they make the code functions and with my partner helping out with the wiring it started becoming easier over time. Now I know a lot of new aspects of coding that I did not before and making arduinos has become easier.