IoT-Based Environmental Monitoring System Using ESP32

IoT-Based Environmental Monitoring System Using ESP32

This project uses the ESP32 microcontroller to monitor environmental parameters such as temperature, humidity, and air quality. It then uploads the data to a cloud platform for real-time visualization. The goal is to create a reliable IoT monitoring system with a user-friendly interface for remote data access.

1. Introduction

Monitoring environmental conditions is critical in various sectors like agriculture, smart homes, and industrial environments. This project demonstrates how to design a compact IoT solution using the ESP32, DHT22 (for temperature and humidity), and MQ-135 (for air quality) sensors. The collected data will be sent to a cloud service (such as ThingSpeak or Blynk) for real-time monitoring.

Key Features:

• Monitors temperature, humidity, and air quality in real-time.
• Data is logged to the cloud for remote access and visualization.
• Low power consumption, with sleep mode implementation.

2. Learning Objectives

By completing this project, you will learn:

• How to interface multiple sensors with the ESP32.
• How to connect the ESP32 to a cloud IoT platform.
• How to program the ESP32 for data acquisition and transmission.
• Power management for IoT devices.

3. Tools and Components

Hardware:

• ESP32 Dev Board
• DHT22 Sensor – Temperature and humidity sensor
• MQ-135 Sensor – Air quality sensor
• 10kΩ Resistors (for pull-up configuration)
• Breadboard and jumper wires
• Power supply (5V)

Software:

• Arduino IDE (with ESP32 support installed)
• ThingSpeak or Blynk IoT Platform
• Libraries: WiFi.h, DHT.h, and HTTPClient.h

4. Background and Definitions

ESP32

The ESP32 is a low-cost, low-power system-on-chip microcontroller with integrated Wi-Fi and Bluetooth. It’s highly suitable for IoT applications due to its versatility.

DHT22 Sensor

A digital sensor for measuring temperature and humidity. It offers high accuracy and reliability compared to other DHT variants.

MQ-135 Sensor

An air quality sensor used to detect a wide range of gases, including ammonia, sulfide, and benzene vapor, making it ideal for air quality monitoring.

5. Step-by-Step Guide

Step 1: Circuit Design

The circuit connects the DHT22 and MQ-135 sensors to the ESP32:

• DHT22 Connections:
  • VCC → 3.3V
  • GND → GND
  • Data → GPIO 4 (with a 10kΩ pull-up resistor)
• MQ-135 Connections:
  • VCC → 5V
  • GND → GND
  • Analog Output → GPIO 34
• ESP32 Power Supply: Connect the ESP32 to a 5V power source through USB or an external power supply.

Diagram Description:

• Draw the ESP32 in the center with connections radiating to the DHT22 and MQ-135.
• Use different colored lines to represent power, ground, and data connections.

I can generate this circuit diagram if you want it visualized.

Step 2: Programming the ESP32

1. Set Up the Arduino IDE for ESP32
   Ensure that the ESP32 board is added to the Arduino IDE. Install the necessary libraries (DHT.h, WiFi.h, HTTPClient.h).
2. Full Source Code:

#include <WiFi.h>
#include <HTTPClient.h>
#include <DHT.h>

#define DHTPIN 4      // GPIO pin where the DHT22 is connected
#define DHTTYPE DHT22
#define MQ135_PIN 34  // Analog pin for MQ-135 sensor

DHT dht(DHTPIN, DHTTYPE);

// Replace with your Wi-Fi credentials
const char* ssid = "YOUR_SSID";
const char* password = "YOUR_PASSWORD";

// ThingSpeak or your IoT endpoint
const char* serverName = "http://api.thingspeak.com/update?api_key=YOUR_API_KEY";

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);

  Serial.print("Connecting to Wi-Fi");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nWi-Fi connected.");
  
  dht.begin();
}

void loop() {
  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();
  int airQuality = analogRead(MQ135_PIN);

  if (isnan(temperature) || isnan(humidity)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    String serverPath = serverName + "&field1=" + String(temperature) + "&field2=" + String(humidity) + "&field3=" + String(airQuality);
    
    http.begin(serverPath.c_str());
    int httpResponseCode = http.GET();

    if (httpResponseCode > 0) {
      Serial.print("HTTP Response code: ");
      Serial.println(httpResponseCode);
    } else {
      Serial.print("Error code: ");
      Serial.println(httpResponseCode);
    }
    http.end();
  } else {
    Serial.println("Wi-Fi Disconnected");
  }
  
  delay(30000);  // Send data every 30 seconds
}

6. Testing and Debugging Tips

• Sensor Reading Errors: If the DHT22 fails to provide readings, check the pull-up resistor and connections.
• Wi-Fi Connection Issues: Ensure your credentials are correct and that the ESP32 is within Wi-Fi range.
• Cloud Data Not Updating: Verify the API key and URL endpoint for your IoT platform.

7. Extensions

Here are some ideas for extending the project:

• Add a PM2.5 Sensor for monitoring fine particulate matter.
• Use OLED Display to show real-time data locally.
• Mobile Notifications with Blynk for threshold alerts.
• Low Power Mode: Implement deep sleep to conserve battery life.