📘 Home Security System ( WiFi Hotspot Version )

🎯 Objective of This Lesson

Students will learn:

• What is Access Point (AP Mode)

• How ESP32 creates its own WiFi network

• How to connect mobile directly to ESP32

• How to receive motion alerts via WiFi Serial Terminal app

🔌 Hardware Reminder

📡 How This System Works

1️⃣ ESP32 creates WiFi hotspot
2️⃣ Mobile connects to ESP32 WiFi
3️⃣ WiFi Serial Terminal app connects via IP & Port
4️⃣ Motion alerts are sent using TCP communication

No router needed.

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

#include <WiFi.h>

#define PIR_PIN 27

// -------- WiFi Access Point --------
const char* ssid = "HomeSecurity_AP";
const char* password = "12345678";

WiFiServer server(80);

int motionState = 0;
int lastState = 0;

void setup() {

Serial.begin(115200);
pinMode(PIR_PIN, INPUT);

// Start WiFi Access Point
WiFi.softAP(ssid, password);
server.begin();

Serial.println("WiFi Hotspot Started");
Serial.print("IP Address: ");
Serial.println(WiFi.softAPIP());

Serial.println("Warming up PIR Sensor...");
delay(30000);
Serial.println("System Ready!");
}

void loop() {

WiFiClient client = server.available();

if (client) {

motionState = digitalRead(PIR_PIN);

if (motionState == HIGH && lastState == LOW) {
client.println("⚠ MOTION DETECTED! Intruder Alert!");
lastState = HIGH;
}

else if (motionState == LOW && lastState == HIGH) {
client.println("Area Clear - No Motion");
lastState = LOW;
}

delay(200);
}
}

🧠 Code Explanation (Step-by-Step)

1️⃣ Include WiFi Library

Allows ESP32 to use WiFi features.

2️⃣ Create Hotspot (AP Mode)

ESP32 becomes a WiFi network.

Network Name:
👉 HomeSecurity_AP

Password:
👉 12345678

3️⃣ Start TCP Server

Creates TCP server on Port 80.

Port 80 is standard communication port.

4️⃣ Get Hotspot IP Address

Default IP is usually:

👉 192.168.4.1

Students must enter this in WiFi Serial Terminal app.

5️⃣ Detect Client Connection

If mobile connects → client becomes active.

6️⃣ Motion Detection Logic

If motion detected:

Send:

⚠ MOTION DETECTED! Intruder Alert!

If motion stops:

Send:

Area Clear – No Motion

📱 How to Connect (WiFi Serial Terminal App)

Step 1 – Upload code
Step 2 – Open Serial Monitor
Step 3 – Note IP address (usually 192.168.4.1)
Step 4 – Connect phone to WiFi → HomeSecurity_AP
Step 5 – Open WiFi Serial Terminal app
Step 6 – Enter:

IP → 192.168.4.1
Port → 80

Step 7 – Connect

Now motion alerts will appear on mobile.

📊 Example WiFi Output

⚠ MOTION DETECTED! Intruder Alert!

Area Clear – No Motion

🎓 Learning Outcomes

Students now understand:

• Access Point Mode

• TCP communication

• Wireless motion alerts

• Local IoT communication without internet