📘 Lesson 11.3 – Home Security System ( Bluetooth Motion Alert Version )

🎯 Objective of This Lesson

Students will learn:

• How to enable Bluetooth in ESP32

• How to send motion alert to mobile

• How to monitor intrusion wirelessly

• Real-time motion notification system

Only:

👉 ESP32
👉 PIR Sensor
👉 Mobile Bluetooth Terminal App

📱 Required Mobile App

Install:

• Serial Bluetooth Terminal (Android)
  or

• Any Bluetooth Terminal App

🔌 Hardware Reminder

🧾 Complete ESP32 Code (Bluetooth Version – Copy & Paste)

#include "BluetoothSerial.h"

BluetoothSerial SerialBT;

#define PIR_PIN 27

int motionState = 0;
int lastState = 0;

void setup() {

Serial.begin(115200);
SerialBT.begin("Home_Security"); // Bluetooth device name

pinMode(PIR_PIN, INPUT);

Serial.println("Home Security System Started...");
SerialBT.println("Connected to Home Security System");

Serial.println("Warming up PIR Sensor...");
SerialBT.println("Warming up PIR Sensor...");
delay(30000);

Serial.println("System Ready!");
SerialBT.println("System Ready!");
}

void loop() {

motionState = digitalRead(PIR_PIN);

if (motionState == HIGH && lastState == LOW) {

Serial.println("⚠ MOTION DETECTED! Intruder Alert!");
SerialBT.println("⚠ MOTION DETECTED! Intruder Alert!");

lastState = HIGH;
}

else if (motionState == LOW && lastState == HIGH) {

Serial.println("Area Clear - No Motion");
SerialBT.println("Area Clear - No Motion");

lastState = LOW;
}

delay(200);
}

🧠 Code Explanation (Step-by-Step)

1️⃣ Include Bluetooth Library

This enables Bluetooth communication in ESP32.

2️⃣ Create Bluetooth Object

Used to send data to mobile device.

3️⃣ Start Bluetooth

Sets device name visible in Bluetooth list.

Mobile will detect:

👉 Home_Security

4️⃣ Warm-Up Delay

PIR requires 30 seconds stabilization time.

5️⃣ Read PIR Output

Returns:

HIGH → Motion detected
LOW → No motion

6️⃣ Motion Alert Logic

Motion just started → Send alert once.

Prevents repeated spam messages.

7️⃣ Motion End Detection

Motion stopped → Send clear message.

8️⃣ Why Use Both Serial & SerialBT?

• Serial → Computer debugging

• SerialBT → Mobile monitoring

Professional development practice.

📱 How to Connect Mobile

1️⃣ Upload code
2️⃣ Turn ON Bluetooth
3️⃣ Open Bluetooth Terminal app
4️⃣ Search for device
5️⃣ Select Home_Security
6️⃣ Connect

Now motion alerts will appear on mobile.

📊 Example Bluetooth Output

System Ready!

⚠ MOTION DETECTED! Intruder Alert!

Area Clear – No Motion

🎓 Learning Outcomes

Students now understand:

• Bluetooth communication

• Wireless motion alert system

• State change detection

• Real-time intrusion monitoring