Arduino Intruder Alarm Using PIR ~ The Young Engineerzz

Passive infrared sensors are great for motion detection projects, i brought it recently for a college project and i was actually being tempted to use it .

Unfortunately all i got from The INTERNET were not that much fun .

I took out some of my favorite old parts and started tinkering with it .

The result was a motion detected Intruder alarm.

I added two led to simulated police siren light and added Siren to it for the real fun.

The sensitivity was made to medium values , and then the fun began .

Step 1: Materials

So for this project we would need

Arduino UNO(compatibles ones work too);
1x Blue Led
1x Red Led
PIR Sensor
12 V Siren

You will also need a powerbank as a power source

Step 2: Connecting the sensor and the components

The PIR sensor has three pins

Vcc
Data
Ground

so the connections are simple we connect

Vcc to 5v

Gnd to Gnd

Data to 3

Now for the siren

Connect

positive to pin 11

Gnd to Gnd

Lastlat the Led are connected to 7 and 8

Step 4: Code


int calibrationTime = 45;        

//the time when the sensor outputs a low impulse
long unsigned int lowIn;         

//the amount of milliseconds the sensor has to be low 
//before we assume all motion has stopped
long unsigned int pause = 5000;  

boolean lockLow = true;
boolean takeLowTime;  

int pirPin = 3;    //the digital pin connected to the PIR sensor's output
int ledPin = 11;
int led1=8;
int led2=7;


/////////////////////////////
//SETUP
void setup(){
  Serial.begin(9600);
  pinMode(pirPin, INPUT);
  pinMode(ledPin, OUTPUT);
  pinMode(led1,OUTPUT);
  pinMode(led2,OUTPUT);
  
  digitalWrite(pirPin, LOW);

  //give the sensor some time to calibrate
  Serial.print("calibrating sensor ");
    for(int i = 0; i < calibrationTime; i++){
      Serial.print(".");
      delay(1000);
      }
    Serial.println(" done");
    Serial.println("SENSOR ACTIVE");
    delay(50);
  }
  void alert()
  {
  
    digitalWrite(led1,HIGH);
    digitalWrite(led2,LOW);
    
    delay(50);
    digitalWrite(led2,HIGH);digitalWrite(led1,LOW);
    delay(50);
    
  }

void loop(){

     if(digitalRead(pirPin) == HIGH){
       analogWrite(ledPin, 50);   
       alert();
       digitalWrite(led1,LOW);
              digitalWrite(led2,LOW);

       ;//the led visualizes the sensors output pin state
       if(lockLow){  
         //makes sure we wait for a transition to LOW before any further output is made:
         lockLow = false;            
         Serial.println("---");
         Serial.print("motion detected at ");
         Serial.print(millis()/1000);
         Serial.println(" sec"); 
         delay(50);
         }         
         takeLowTime = true;
       }

     if(digitalRead(pirPin) == LOW){   
       
       digitalWrite(ledPin, LOW);  //the led visualizes the sensors output pin state

       if(takeLowTime){
        lowIn = millis();          //save the time of the transition from high to LOW
        takeLowTime = false;       //make sure this is only done at the start of a LOW phase
        }
       //if the sensor is low for more than the given pause, 
       //we assume that no more motion is going to happen
       if(!lockLow && millis() - lowIn > pause){  
           //makes sure this block of code is only executed again after 
           //a new motion sequence has been detected
           lockLow = true;                        
           Serial.print("motion ended at ");      //output
           Serial.print((millis() - pause)/1000);
           Serial.println(" sec");
           delay(50);
           }
       }
  }