IoT-Based Environmental Monitoring System

A real-time environmental monitoring system built with ESP32 that collects and transmits temperature, humidity, air quality, and light level data to ThingSpeak for cloud-based logging and visualization.

Overview

This project implements a complete IoT solution for environmental monitoring. The system continuously reads sensor data from a network of environmental sensors connected to an ESP32 microcontroller, processes the readings, and uploads them to ThingSpeak—a popular IoT analytics platform—where data can be visualized, analyzed, and stored indefinitely.

Features

• Real-time Data Collection: Continuously monitors environmental parameters every 15 seconds
• Temperature & Humidity Monitoring: Uses DHT22 sensor for accurate climate readings
• Light Level Detection: LDR sensor measures ambient light intensity
• Air Quality Simulation: Potentiometer simulates MQ-135 air quality sensor for testing
• WiFi Connectivity: ESP32 connects to networks for seamless cloud data transmission
• ThingSpeak Integration: Automatic data upload to ThingSpeak platform for cloud storage and visualization
• Serial Monitoring: Real-time data display via serial console for debugging and verification
• Optimized Update Interval: 15-second intervals respect ThingSpeak API rate limits

Hardware Requirements

Component	Specifications	GPIO Pin
ESP32	Microcontroller with WiFi/Bluetooth	N/A
DHT22	Temperature & Humidity Sensor	GPIO4
LDR	Light Dependent Resistor (Photoresistor)	GPIO34 (ADC)
Potentiometer	10kΩ resistor (simulates MQ-135 air quality)	GPIO35 (ADC)
Wokwi Simulator	Online simulation platform	N/A

How It Works

1. Sensor Reading: The system reads temperature and humidity from the DHT22 sensor and analog values from the LDR and potentiometer
2. Data Processing: Raw values are converted to user-friendly units (temperature in °C, humidity in %, light level 0-100%, air quality 0-500 scale)
3. Serial Output: Data is printed to the serial console for real-time monitoring
4. WiFi Connection: Establishes connection to the configured WiFi network
5. Cloud Upload: Every 15 seconds, data is sent to ThingSpeak using HTTP GET requests
6. Data Visualization: ThingSpeak displays the data in real-time charts and graphs

Measured Parameters

• Temperature: Measured in Celsius (°C) via DHT22
• Humidity: Measured as percentage (%) via DHT22
• Air Quality: Mapped to 0-500 scale (simulated with potentiometer)
• Light Level: Measured as percentage (0-100%) via LDR

Required Libraries

• DHT sensor library: Handles DHT22 temperature and humidity sensor communication
• Adafruit Unified Sensor: Provides standardized sensor interface
• WiFi.h: Built-in ESP32 library for WiFi connectivity
• HTTPClient.h: Built-in ESP32 library for HTTP communications

Setup Instructions

1. Install Required Libraries (Wokwi)

The libraries are automatically imported from libraries.txt. The required libraries are:

• DHT sensor library
• Adafruit Unified Sensor

2. Configure WiFi Credentials

Edit the credentials in sketch.ino:

const char* ssid = "Wokwi-GUEST";        // Your network SSID
const char* password = "";                 // Your network password

3. Set ThingSpeak API Key

Update the API key in sketch.ino:

String apiKey = "DOVDZPTBBR0G7NNU";       // Your ThingSpeak API key

4. Hardware Wiring

• Connect DHT22 data pin to GPIO4
• Connect LDR analog output to GPIO34
• Connect potentiometer wiper to GPIO35

5. Upload & Monitor

• Upload the sketch to your ESP32
• Open the Serial Monitor at 115200 baud to view real-time data
• Visit ThingSpeak to see cloud-stored data and visualizations

ThingSpeak Channel Configuration

The system sends data to four ThingSpeak fields:

• Field 1: Temperature (°C)
• Field 2: Humidity (%)
• Field 3: Air Quality (0-500)
• Field 4: Light Level (0-100%)

Visit ThingSpeak to create a channel and view your environmental data in real-time charts.

Project Structure

IoT-Based-Environmental-Monitoring-System/
├── README.md                    # Project documentation
├── code/
│   ├── sketch.ino              # ESP32 Arduino sketch (main code)
│   └── libraries.txt           # Required libraries list
└── media/
    ├── circuit-diagram.png     # Hardware connection diagram
    └── ThingSpeak_chart.png    # Example data visualization

Serial Output Example

WiFi connected!
Temp: 28.45 °C, Hum: 65.30 %, Air: 245.67, Light: 78.50 %
ThingSpeak response: 200
Temp: 28.47 °C, Hum: 65.28 %, Air: 246.12, Light: 79.10 %
ThingSpeak response: 200

Sensor Calibration

• LDR: Mapped to 0-100% where 0 is complete darkness and 100 is maximum brightness
• Air Quality Potentiometer: Mapped to 0-500 scale to simulate realistic MQ-135 readings (in a real deployment, this would be replaced with an actual MQ-135 sensor)

Troubleshooting

Issue	Solution
DHT22 read failures	Ensure sensor is properly wired and powered; check GPIO4 connection
WiFi connection fails	Verify SSID and password are correct for your network
ThingSpeak errors	Confirm API key is valid and has write permissions; check internet connectivity
Serial shows no data	Verify baud rate is set to 115200 and correct COM port is selected

Future Enhancements

• Add actual MQ-135 air quality sensor for real air quality measurements
• Implement data logging to SD card for local backup
• Add mobile app for remote monitoring
• Integrate alerts for abnormal environmental conditions
• Support multiple sensor nodes with mesh networking
• Add battery power with low-power sleep modes

Platform Notes

This project is designed to run on the Wokwi Online Simulator for Arduino/ESP32, making it accessible without physical hardware. For production deployment on real hardware, ensure proper power supply and environmental protection for outdoor sensors.

License

This project is open-source and available for educational and personal use.