IoT Environmental Monitoring System with Fire and Smoke Detection (ESP32)

Project Benefits

This project is an IoT-based environmental monitoring system using an ESP32 microcontroller. It integrates sensors for temperature, humidity, smoke, carbon monoxide (CO), and dust to:

• Detect potential fire or smoke hazards in real-time.
• Provide alerts through a buzzer and indicator LEDs.
• Send sensor data to an MQTT broker for remote monitoring.
• Improve safety and air quality awareness in homes, offices, warehouses, or labs.

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Hardware Requirements

• ESP32 (microcontroller)
• DHT22 (temperature & humidity sensor)
• MQ7 (carbon monoxide sensor)
• MQ135 (air quality / smoke sensor)
• Dust sensor (optical-based)
• Buzzer, Red/Yellow/Green LEDs
• Wi-Fi connection
• MQTT Broker (e.g., broker.emqx.io)

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Required Libraries

• WiFi.h
• PubSubClient.h
• DHT.h
• ArduinoJson.h

Install these via Arduino IDE Library Manager.

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Configuration

• Wi-Fi SSID: Your-Wifi-name, example: jo-wifi
• Password: Your-passowrd-name, example: 123
• MQTT Broker: broker.emqx.io
• Port: 1883
• MQTT Topic: example: IoT/group8

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Monitoring Web

click this Link to direct you to the websiete monitorng repository

Sensor Design

Code Overview

WiFi Setup

void setupWifi()

Connects the ESP32 to the configured Wi-Fi network and prints the local IP address.

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MQTT Reconnection

void reconnectMQTT()

Attempts to reconnect to the MQTT broker if disconnected, using client ID ESP32Client.

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Read Temperature & Humidity

float readDHTTemperature()
float readDHTHumidity()

Reads values from the DHT22 sensor. Returns 0 if the reading fails.

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Dust Sensor Reading

int readDustSensor()

Triggers the LED inside the dust sensor, reads analog value from dust pin, and calculates concentration.

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CO Conversion (MQ7)

float convertMQ7(int rawValue)

Converts raw analog value into an estimated CO concentration in ppm using a basic formula.

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MQTT Publish

void publishSensorData(...)

Sends a JSON-formatted payload to the MQTT topic with sensor readings and environment status.

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Output Control

void setOutputs(bool buzzer, bool red, bool yellow, bool green)

Controls the buzzer and LEDs (ON/OFF) based on the condition detected.

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Setup

void setup()

• Initializes sensors and pin modes.
• Turns on the green LED as default state.
• Connects to Wi-Fi and sets up MQTT.

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Main Loop

void loop()

• Reads all sensor data.

• Evaluates the following conditions:

  • 🔴 FIRE DETECTED: MQ135 > 1800, Temp > 45°C, Dust > 2000, Humidity < 30%
  • 🟡 SMOKE DETECTED: MQ135 > 800 and CO > 50 ppm
  • 🟢 NORMAL: All values within safe range

• Controls outputs and sends data via MQTT every second.

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Example JSON Payload

{
  "temperature": 30.5,
  "humidity": 45.3,
  "dust": 1000,
  "co": 80.2,
  "air_quality": 900,
  "status": "WARNING: Smoke detected"
}

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Notes

• For accurate CO measurement, calibrate the MQ7 sensor’s R0 resistance value.
• MQTT data can be visualized using tools like Node-RED, ThingsBoard, or custom dashboards.
• Can be extended with cloud logging or mobile notifications.

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License

This project is open-source and free to use for educational and non-commercial purposes.

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Contributors

Developed by Group 8 - IoT Project 2025

Hotel Room Design 1 (700cm x 320cm)