How to Create a PIR Motion Sensor Alarm Using TinkerCAD

Introduction

A PIR (Passive Infrared) motion sensor alarm is a simple yet effective way to detect motion in a given area. These sensors are widely used in security systems, automatic lighting controls, and other applications where motion detection is crucial. In this tutorial, we’ll walk you through creating a PIR motion sensor alarm circuit using TinkerCAD, an online 3D modeling and circuit design tool.

Materials Needed

Before we start, make sure you have the following components in TinkerCAD:

• Breadboard

• Arduino Uno

• PIR Motion Sensor

• Buzzer

• LED

• Resistor (220Ω)

• Jumper Wires

Step 1: Set Up the Components

1. Breadboard and Arduino: Open TinkerCAD and start a new circuit project. Drag and drop an Arduino Uno onto the workspace. Next, add a breadboard to the setup.

2. PIR Motion Sensor: Place the PIR motion sensor on the breadboard. The sensor has three pins:

   • VCC (Power)

   • GND (Ground)

   • OUT (Signal)

   Connect the VCC pin to the 5V pin on the Arduino, the GND pin to the GND pin on the Arduino, and the OUT pin to digital pin 2 on the Arduino.

3. Buzzer: Add a buzzer to the breadboard. Connect the positive leg (longer leg) of the buzzer to digital pin 8 on the Arduino and the negative leg to GND.

4. LED and Resistor: Place an LED on the breadboard. Connect the longer leg (anode) of the LED to digital pin 13 on the Arduino via a 220Ω resistor. The shorter leg (cathode) should be connected to GND.

Step 2: Wiring Diagram

Ensure your wiring looks like this:

• PIR Sensor:

  • VCC → 5V on Arduino

  • GND → GND on Arduino

  • OUT → Digital Pin 2 on Arduino

• Buzzer:

  • Positive Leg → Digital Pin 8 on Arduino

  • Negative Leg → GND on Arduino

• LED:

  • Anode (long leg) → Digital Pin 13 on Arduino (through a 220Ω resistor)

  • Cathode (short leg) → GND on Arduino

Step 3: Writing the Code

Now that the circuit is ready, let's write the code to make the alarm work.

int pirPin = 2;      // PIR motion sensor connected to pin 2

int ledPin = 13;     // LED connected to pin 13

int buzzerPin = 8;   // Buzzer connected to pin 8

int pirState = LOW;  // Start with motion sensor off

int val = 0;         // Variable to store the PIR status

void setup() {

  pinMode(pirPin, INPUT);    // Set PIR sensor as input

  pinMode(ledPin, OUTPUT);   // Set LED as output

  pinMode(buzzerPin, OUTPUT);// Set Buzzer as output

  Serial.begin(9600);        // Initialize serial communication

}

void loop() {

  val = digitalRead(pirPin);  // Read PIR sensor value

  if (val == HIGH) {          // If motion is detected

    digitalWrite(ledPin, HIGH); // Turn on LED

    digitalWrite(buzzerPin, HIGH); // Turn on buzzer

    if (pirState == LOW) {

      Serial.println("Motion detected!"); // Print message in serial monitor

      pirState = HIGH;

    }

  } else {

    digitalWrite(ledPin, LOW);  // Turn off LED

    digitalWrite(buzzerPin, LOW); // Turn off buzzer

    if (pirState == HIGH) {

      Serial.println("Motion ended!"); // Print message in serial monitor

      pirState = LOW;

    }

  }

}

Step 4: Simulate the Circuit

1. After writing the code, click the "Start Simulation" button in TinkerCAD.

2. The PIR motion sensor will detect movement. When motion is detected, the LED lights up, the buzzer sounds, and a message is printed to the serial monitor.

3. To stop the alarm, the PIR sensor must no longer detect any movement.

Step 5: Understanding the Code

• The PIR sensor continuously checks for motion. When motion is detected, it sends a HIGH signal to pin 2.

• When the Arduino receives a HIGH signal, it activates the LED and buzzer.

• The system prints messages to the serial monitor to notify you of the motion status.

Conclusion

Congratulations! You've successfully created a PIR motion sensor alarm using TinkerCAD. This simple project introduces you to motion detection and how it can be integrated into various applications. You can further modify this circuit by adding more features, such as using a relay to control larger devices or integrating it with a notification system.

Exploring these kinds of projects will enhance your understanding of electronics and Arduino programming. Keep experimenting and building more complex projects as you grow your skills.

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