🔥 Fire Alarm System

An Arduino-based fire detection alarm that uses an MQ-2 gas/smoke sensor to monitor air quality in real time, displays status on a 16x2 I2C LCD, and triggers a buzzer and LED alert on smoke detection.

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📖 Overview

The Fire Alarm System is a smoke and fire detection project built on an Arduino UNO. An MQ-2 gas sensor continuously reads analog smoke levels and classifies them into three severity tiers — LOW, MEDIUM, and HIGH. The system displays the current status on a 16x2 I2C LCD screen and activates a buzzer and LED indicator when dangerous smoke levels are detected.

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✨ Features

• 🌫️ Three-tier detection — classifies smoke levels as LOW, MEDIUM, or HIGH based on configurable thresholds
• 📺 Real-time LCD display — 16x2 I2C LCD shows live status and smoke level
• 🔔 Buzzer alert — audible alarm triggers only at HIGH smoke level
• 💡 LED indicator — lights up at MEDIUM and HIGH levels as a visual warning
• 🖥️ Serial monitoring — raw sensor values streamed via Serial Monitor (9600 baud) for calibration and debugging

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🛠️ Hardware Components

Component	Quantity
Arduino UNO	1
MQ-2 Gas / Smoke Sensor	1
16x2 I2C LCD Display	1
Piezo Buzzer	1
LED (Blue)	1
Resistor (220Ω)	1
Breadboard	1
Jumper Wires	As needed

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🔌 Pin Connections

Component	Pin	Arduino Pin
MQ-2 Sensor	VCC	5V
MQ-2 Sensor	GND	GND
MQ-2 Sensor	AOUT	A0
LCD (I2C)	VCC	5V
LCD (I2C)	GND	GND
LCD (I2C)	SDA	A4
LCD (I2C)	SCL	A5
Buzzer	Signal	Digital 8
LED (+ 220Ω resistor)	Anode	Digital 9

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🔌 Circuit Diagram

Built and simulated in Tinkercad

Breadboard View:

Schematic View:

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🚀 Getting Started

Prerequisites

• Arduino IDE (1.8.x or 2.x)
• LiquidCrystal_I2C library

Install the library via Arduino IDE Library Manager:

Sketch → Include Library → Manage Libraries → Search "LiquidCrystal I2C" → Install

Installation

1. Clone the repository

git clone https://github.com/deep-chatterjee/Fire-Alarm-System.git
cd Fire-Alarm-System

2. Open the sketch

   • Open Fire_Alarm_System.ino in the Arduino IDE
   • Select your board: Arduino UNO
   • Select the correct COM port

3. Upload to your board

   • Click Upload
   • Open Serial Monitor (baud rate: 9600) to view live sensor readings

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💻 How It Works

MQ-2 sensor reads analog smoke level (0–1023)
               ↓
     Compare against thresholds
    ┌──────────┬───────────┬──────────┐
    │  < 300   │  300–449  │  ≥ 450   │
    │   LOW    │  MEDIUM   │   HIGH   │
    └──────────┴───────────┴──────────┘
         ↓            ↓           ↓
    LCD: SAFE    LCD: Warning  LCD: FIRE ALERT!!!
    Buzzer: OFF  Buzzer: OFF   Buzzer: ON
    LED: OFF     LED: ON       LED: ON

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⚙️ Threshold Configuration

Thresholds can be adjusted in the sketch to suit your environment and sensor:

int lowThreshold    = 300;   // Below this → SAFE
int mediumThreshold = 450;   // Between low & medium → WARNING
                             // Above medium → FIRE ALERT

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📁 Project Structure

Fire-Alarm-System/
├── Fire_Alarm_System.ino              # Arduino sketch
├── Fire_Alarm_System_Circuit.png      # Tinkercad breadboard view
├── Fire_Alarm_System_Schematic.png    # Tinkercad schematic view
└── README.md

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🧠 What I Learned

• Reading and interpreting analog sensor output from an MQ-2 gas sensor
• I2C communication protocol for driving an LCD display with only two signal wires
• Multi-threshold classification logic for graduated alert levels
• Coordinating multiple output peripherals (LCD, buzzer, LED) based on sensor state

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🔮 Future Improvements

• Add a temperature sensor (DHT11/DHT22) for combined fire and heat detection
• Implement PWM buzzer tones that escalate with smoke severity
• Send SMS or push notifications via GSM module (SIM800L) or Wi-Fi (ESP8266)
• Log sensor data to an SD card for historical analysis
• Add a manual reset button to silence the alarm

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👤 Author

Deep Chatterjee
GitHub

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📄 License

This project is licensed under the MIT License — see LICENSE for details.