🌎 ESP32 Environmental Monitoring System 🚀

This project is WiFi-enabled real-time environmental monitoring system built on ESP32 WROOM 32D microcontroller. It captures and displays key atmospheric parameters such as temperature🌡️, humidity💧, PM2.5 dust density🌫️, dust levels💨, air PPM levels🏭 and air quality index(AQI)⚠️ using various sensors. This data is displayed locally on a 128x64 OLED display and also served through a responsive web interface hosted on ESP32 itself over the local network.

🚀 Features

• 📡 WiFi Based Server: ESP32 hosts a dynamic webpage accessible to any device on the same network acting as a webserver
• 🌡️ Temperature monitoring: Captures accurate ambient temperature using digital temperature sensor
• 💧 Humidity Monitoring: uses humidity sensor for relative humidity data
• 🌫️ PM2.5 Air Quality Measurement: Uses dust density sensor to estimate PM2.5 levels
• 💨 Dust Level: Based on PM2.5 level, it classifies the value into dust density levels
• 🏭 Air PPM Levels: Uses air quality/gas detector sensor to estimate PPM levels
• ⚠️ AQI Level: Based on PPM level, it categorizes the value into Air Quality Index
• 🕙 Live Clock with NTP: Fetches real time date and time using NTP(Network Time Protocol)
• 📺 OLED Display Output: Display the readings on a OLED screen
• 🔁 Timed sensor Updates: Reads and updates sensor values after every 60 seconds
• 🌐 Responsive Web Dashboard: Presents clean and styled HTML output of live data

🔧 Hardware Used

🧩 Component	🔍 Description	📦 Model/Type
🧠 Microcontroller	Main controller of the system - with WiFi & Bluetooth	ESP32 WROOM 32D IoT development board
🧠 Secondary Microcontroller	Main controller - To calibrate air quality/dust detector sensor	Arduino UNO Rev3 development board
🌡️ Temperature Sensor	To measure ambient temperature	Dallas Semiconductors DS18B20 Digital Temperature Sensor (Breakout Board)
💧 Humidity Sensor	To measure ambient humidity	DHT11 Sensor (Breakout Board)
🌫️ Dust Sensor	To measure suspended 2.5um particulate matter in air	PM2.5 GP2Y1010AU0F Dust Smoke Particle Sensor
🌫️ Air Quality/Gas Detection Sensor	To measure air quality & Parts Per Million in Air	MQ-135 Air Quality/Gas Detection Sensor (Breakout Board)
📺 Display Screen	To display sensor readings locally	SSD1306 driver based 0.96" 7Pin 128x64 monochromatic(Blue) SPI/I2C OLED display (Breakout Board)
150Ω resistor + 220µF Capacitor	Resistor to limit current in IR LED, Capacitor for signal smoothening	For PM2.5 GP2Y1010AU0F Dust Smoke Particle Sensor
2x 10kΩ resistor	Resistors act as voltage divider to protect ESP32 Analog pins from voltage surge from analog pin of the sensor	For MQ-135 Air Quality/Gas Detection Sensor
🔌 Electrical Components	Prototyping components	Dupont Jumper wires(M-M, M-F, F-F), Breadboard, Acrylic board
🔋 Power Supply	To power the whole system	Laptop USB adapter
🛠️ Multimeter	For voltage, current & continuity testing	Kaiweets HT118E 20000 count Digital Multimeter
🪛 Soldering Iron	For assembling and soldering components	25W soldering iron

📐 Pin Configuration

Module	Pin Name	ESP32 GPIO
OLED Display (SPI)	VCC	5V
	GND	GND
	MOSI	GPIO 23
	CLK(SCK)	GPIO 18
	DC	GPIO 4
	CS	GPIO 5
	RESET	GPIO 16
DHT11 Sensor	VCC	3.3V
	GND	GND
	DATA	GPIO 13
DS18B20 Sensor	VCC	3.3V
	GND	GND
	DATA	GPIO 15
PM2.5 Sensor	V-LED	5V (**through 150ohm resistor & 220uF capacitor)
	LED-GND	GND
	LED Control	GPIO 25
	S-GND	GND
	Vo(Analog Output)	GPIO 34
	VCC	5V
MQ135 Sensor	VCC	5V
	GND	GND
	DO
	AO	GPIO 32 (**Voltage Divider with 2x 10 kilo-ohm resistors)

**Please Note: Make the electrical connections for PM2.5 and MQ135 sensors as shown in pictures in datasheets folder since it includes extra components such as capacitors & resistors

🧠 Software Functionality

✅ Setup

• Sets designated esp32 gpio pins as inputs/outputs
• Configures humidity sensor, temperature sensor, MQ135 sensor
• Configures the oled display to default settings
• Connects ESP32 to WiFi with given credentials having a retry logic for 30sec to establish a connection
• Setup ESP32 as a server to listen to requests sent by other devices on the same network
• Configures time to be fetched from NTP server

✅ Sensor Reading Cycle (every 60 seconds)

• DHT11: Reads Humidity
• DS18B20: Reads temperature with retry logic to avoid invalid readings
• PM2.5 (GP2Y1010AU0F):
  • Activates LED
  • Reads analog voltage
  • Converts voltage into µg/m³
  • Categorizes dust density level
• MQ-135 Sensor:
  • Reads analog voltage
  • Converts voltage into ppm level
  • Categorizes air quality level

🖥️ Display Output (OLED)

• Day, Date, Time
• Humidity(%)
• Temperature(°C)
• PM2.5 Dust Density (µg/m³)
• Air PPM Level
• AQI Level (e.g., Clean Air, Moderate, Unhealthy, Hazardous)

🌐 Web Server Output

• Styled HTML web page accessible at http://<ESP32_IP> showing all live sensor readings

🖥️ Serial Output Monitor

• Day, Date, Time
• Humidity(%)
• Temperature(°C)
• PM2.5 Dust Density (µg/m³)
• PM2.5 Dust Level
• Air PPM Level
• AQI Level (e.g., Clean Air, Moderate, Unhealthy, Hazardous)

🕓 Time Sync via NTP

• NTP Server: pool.ntp.org
• Timezone: GMT + 5:30(Indian Standard Time)
• Displays synchronized date, time, and day of the week

🧪 Dust Level Mapping Logic

PM2.5 Range (µg/m³)	Air Quality Level
0 - 12	🟢 Clean Air
12.1 - 35.4	🟡 Moderate
35.5 - 55.4	🟠 Unhealthy for Sensitive Groups
55.5 - 150.4	🔴 Unhealthy
150.5 - 250.4	🟣 Very Unhealthy
250.5+	🟤 Hazardous

🚥 Air Quality Mapping Logic

Air PPM Level	Air Quality Level
0 - 50.0	🟢 Clean Air
50.1 - 100.0	🟡 Moderate
100.1 - 150.0	🟠 Unhealthy for Sensitive Groups
150.1 - 200.0	🔴 Unhealthy
200.1 - 300.0	🟣 Very Unhealthy
300.1+	🟤 Hazardous

⚙️ MQ135 Sensor Prerequisites & Calibration Instructions

MQ135 air quality/dust detector sensor requires an initial burn-in time of 24-48hrs(brand new sensor). For that purpose, please connect the following mentioned pins of the sensor to arduino UNO, powering UNO through PC and burn in for atleast 24hrs to get stable results.

Module	Pin Name	Arduino UNO GPIO
MQ135 Sensor	VCC	5V
	GND	GND

Once preheat is complete, perform calibration through arduino UNO to determine RO value of the sensor:

1. Install Arduino IDE and Arduino UNO board support via board manager
2. Make the necessary electrical connections(VCC, GND and analog input)

Module	Pin Name	Arduino GPIO
MQ135 Sensor	VCC	5V
	GND	GND
	A0	A0 (No voltage divider required)

4. Select the correct port and board(Arduino UNO)
5. Upload the code from sensor_calibration folder to Arduino UNO
6. Open Serial Monitor -> Get the RO values displayed
7. Open the project code from src folder and make the following changes to RO and RL

void setup_MQ135()
{
  delay(10000);
  MQ135.setRegressionMethod(1); 
  MQ135.init();

  MQ135.setRL(20); // Look up this value from the datasheet
  MQ135.setR0(28.8); // Punch the RO value received from sensor calibration
  MQ135.setA(110.47);
  MQ135.setB(-2.862);
}

8. Once finished, proceed with main project execution

⚙️ Project Setup Instructions

1. Install Arduino IDE and ESP32 board support via board manager
2. Make the necessary electrical connections
3. Install required libraries
   • WiFi.h
   • DHT.h
   • OneWire.h
   • DallasTemperature.h
   • AdaFruit_SSD1306.h
   • AdaFruit_GFX.h
   • MQUnifiedsensor.h
4. Configure WiFi credentials in the code:

const char* ssid = "Your_SSID";
const char* password = "Your_PASSWORD";

5. Select the correct port and board
6. Upload the code from src folder to ESP32
7. Open Serial Monitor -> Get the ESP32 IP Address -> Open in Browser(ensure you are on same netowrk as ESP32)

📂 File Structure

ESP32-Environmental-Monitoring/
|--- sensor_calibration/
|       |--- mq135_sensor_calibrate.ino
|--- Datasheets/
|       |--- ESP32-WROOM-32D_Pinout.png
|       |--- DHT11_Pinout.png
|       |--- Dust_Sensor_Pinout.png
|       |--- OLED_Display_Pinout.png
|       |--- ESP32_DevBoard_Pinout.png
|       |--- Dust_Sensor_Connection.png
|       |--- MQ135_sensor_pinout.png
|       |--- MQ135_sensor_voltagedivider.png
|       |--- DS18B20_Pinout.png
|       |--- DS18B20_Datasheet.pdf
|       |--- ESP32_Datasheet.pdf
|       |--- PM2.5_Datasheet.pdf
|       |--- DHT11_Datasheet.pdf
|       |--- MQ135_datasheet.pdf
|--- images/  
|       |--- OLED_Display.jpeg
|       |--- SerialOutput1.png
|       |--- Setup1.jpeg
|       |--- Setup2.jpeg
|       |--- WebInterface.jpeg
|--- src/  
|       |--- environmental_monitoring_system.ino  
|--- LICENSE  
|--- README.md  

🛠️ Future Improvements

• Battery powered deployment
• Mobile notification for threshold breach
• Data logging on a server like Raspberry Pi/PC for storage and data analysis
• Integration with IoT cloud based dashboards like Blynk, ThingsBoard, Home Assistant
• Accessing ESP32 webserver from around the world(outside home/local network)

📸 Project Setup

📸 OLED Screen Readings

📸 Web Interface Display

📸 Serial Monitor Output

🙌 Acknowledgements

• Inspired by practical environmental IoT monitoring solutions - targeted for deployment in a household setup
• Thanks to extensive libraries by Adafruit, Dallas Semiconductors

📜 License

This project is open souce under MIT License

🧑‍💻 Author

🧑‍💻 Anmol Singh
📍 Pune, India