IoT Air Quality & Weather Monitoring with ESP32 & BME688

Monitoring indoor air quality is important for maintaining a healthy living environment. In this tutorial, we will learn how to build a smart IoT-based air quality monitoring system using ESP32 and BME688 sensors that measure temperature, humidity, atmospheric pressure, and gas levels (IAQ—Indoor Air Quality). This system can send real-time data to a web dashboard for easy access from any device on your local network.

Unlike older sensors like BME280 and BME680, BME688 is an upgraded version with gas sensing capabilities, making it the best for Air quality detection, Weather station, and IoT applications. Checkout IoT Based Temperature Monitoring With Blynk 2.0 & Raspberry Pi

Components Required

You can purchase all these components from Amazon or AliExpress.

S.N	Component	Quantity	Purchase Link
1	ESP32 Board	1	Amazon / AliExpress
2	BME688 Sensor	1	Amazon / AliExpress
3	Jumper Wires	6-8	Amazon / AliExpress
4	Breadboard	1	Amazon / AliExpress
5	Micro-USB Cable	1	Amazon / AliExpress

BME688 Temperature, Humidity, Pressure, and Gas Sensor

The BME688 is an advanced environmental sensor from Bosch, capable of measuring temperature, humidity, pressure, and air quality. It builds on the BME280 and BMP280 by adding a MOX gas sensor, which detects volatile organic compounds (VOCs), ethanol, alcohol, and carbon monoxide—making it great for air quality monitoring.

The BME688 is Bosch’s latest environmental sensor with AI-based gas detection and air quality monitoring. It supports I2C/SPI communication with a voltage range of 1.71V to 3.6V. The sensor measures VOCs, CO2, temperature (±1°C), humidity (±3% RH), and pressure (±1 hPa).

BME688 Pinout & Wiring

Power Pins:

VIN / VCC: 3V to 5V power supply
GND: Ground
3Vo: 3.3V regulated output

SPI Pins (for fast data transfer):

SDO: Data output
CS: Chip Select
SDI: Data input
SCK: Clock signal

I2C Pins (for simple connections):

SDA (SDI): Data line
SCL (SCK): Clock line
ADDR: Changes I2C address

Share SDI, SDO, and SCK for multiple sensors, but use a different CS pin.

Wiring: ESP32 & BME688 Sensor

Connect the BME688 sensor to the ESP32 using I2C:

BME688 Pin	ESP32 Pin
VCC	3.3V
GND	GND
SCL	GPIO 22
SDA	GPIO 21

Note: The default I2C address of BME688 is 0x76. If needed, you can change it to 0x77 by connecting SDO to VDDIO instead of GND.

~~Power the ESP32 via USB or an external power supply.~~

Below is the connection diagram of the BME680 Sensor with the ESP32 Board. You can use the breadboard to assemble the circuit.

Programming ESP32 for BME688

To use BME688 with ESP32, we need to install some libraries.

Required Libraries

Adafruit BME688 Library
Adafruit Unified Sensor Library

Installing Libraries in Arduino IDE

Open Arduino IDE
Go to Sketch → Include Library → Manage Libraries
Search for BME688 and install Adafruit BME688
Search for Adafruit Unified Sensor and install it

Source Code – BME688 IoT Air Quality & Weather Monitoring with ESP32

#include <Wire.h>
#include <SPI.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME680.h>
#include <WiFi.h>
#include <WebServer.h>
#include <SPIFFS.h>
#include <ArduinoJson.h>
#include <time.h>

#define SEALEVELPRESSURE_HPA (1013.25)

Adafruit_BME680 bme; // I2C

// Environmental data structure
struct SensorData {
    float temperature;
    float humidity;
    float pressure;
    float gasResistance;
    float altitude;
    float dewPoint;
    float airQualityIndex;
    String timestamp;
    unsigned long lastUpdate;
};

SensorData sensorData;

// Replace with your network credentials
const char* ssid = "ESP";
const char* password = "aaaaaaaa";

// Time settings
const char* ntpServer = "pool.ntp.org";
const long gmtOffset_sec = 0;
const int daylightOffset_sec = 3600;

// Create WebServer object on port 80
WebServer server(80);

// Cached HTML content
String cachedHTML;

// Function prototypes
void handleRoot();
void handleNotFound();
void handleData();
void readSensorData();
float calculateAirQualityIndex(float gas, float humidity);
float dewPointCalculation(float temperature, float humidity);
String getTimeString();
void setupTime();
String getHTML();
void reconnectWiFi();

void setup() {
    Serial.begin(115200);
    delay(100);
    
    Serial.println(F("BME688 Environmental Monitoring System - Initializing..."));
    
    if (!SPIFFS.begin(true)) {
        Serial.println("SPIFFS Mount Failed - will use embedded HTML");
    } else {
        Serial.println("SPIFFS Mounted Successfully");
    }

    if (!bme.begin()) {
        Serial.println("Could not find a valid BME688 sensor, check wiring!");
        while (1) {
            delay(1000);
        }
    }
    
    bme.setTemperatureOversampling(BME680_OS_8X);
    bme.setHumidityOversampling(BME680_OS_4X);
    bme.setPressureOversampling(BME680_OS_4X);
    bme.setIIRFilterSize(BME680_FILTER_SIZE_3);
    bme.setGasHeater(320, 150);
    Serial.println("BME688 sensor configuration complete");

    reconnectWiFi();
    setupTime();
    
    server.on("/", HTTP_GET, handleRoot);
    server.on("/data", HTTP_GET, handleData);
    server.onNotFound(handleNotFound);
    
    server.begin();
    Serial.print("Web server started at http://");
    Serial.println(WiFi.localIP());
    
    readSensorData();
}

void loop() {
    if (WiFi.status() != WL_CONNECTED) {
        reconnectWiFi();
    }
    server.handleClient();
    
    static unsigned long lastReadTime = 0;
    if (millis() - lastReadTime > 5000) {
        readSensorData();
        lastReadTime = millis();
    }
}

void reconnectWiFi() {
    if (WiFi.status() != WL_CONNECTED) {
        Serial.println("Connecting to WiFi...");
        WiFi.begin(ssid, password);
        
        // Wait up to 20 seconds for connection
        int timeout = 0;
        while (WiFi.status() != WL_CONNECTED && timeout < 40) {
            delay(500);
            Serial.print(".");
            timeout++;
        }
        
        if (WiFi.status() == WL_CONNECTED) {
            Serial.println("\nWiFi connected!");
            Serial.print("IP address: ");
            Serial.println(WiFi.localIP());
        } else {
            Serial.println("\nWiFi connection failed!");
        }
    }
}

void setupTime() {
    configTime(gmtOffset_sec, daylightOffset_sec, ntpServer);
    struct tm timeinfo;
    if (!getLocalTime(&timeinfo)) {
        Serial.println("Failed to obtain time from NTP server");
    }
}

String getTimeString() {
    struct tm timeinfo;
    if (!getLocalTime(&timeinfo)) {
        return "Time not available";
    }
    
    char timeStr[20];
    strftime(timeStr, sizeof(timeStr), "%Y-%m-%d %H:%M:%S", &timeinfo);
    return String(timeStr);
}

void readSensorData() {
    unsigned long endTime = bme.beginReading();
    if (endTime == 0) {
        Serial.println("Failed to begin reading :(");
        return;
    }
    
    delay(50); // Allow time for measurement

    if (!bme.endReading()) {
        Serial.println("Failed to complete reading :(");
        return;
    }

    sensorData.temperature = bme.temperature;
    sensorData.humidity = bme.humidity;
    sensorData.pressure = bme.pressure / 100.0F;
    sensorData.gasResistance = bme.gas_resistance / 1000.0;
    sensorData.altitude = bme.readAltitude(SEALEVELPRESSURE_HPA);
    sensorData.dewPoint = dewPointCalculation(sensorData.temperature, sensorData.humidity);
    sensorData.airQualityIndex = calculateAirQualityIndex(sensorData.gasResistance, sensorData.humidity);
    sensorData.timestamp = getTimeString();
    sensorData.lastUpdate = millis();
    
    Serial.println("New Sensor Readings:");
    Serial.printf("Temperature: %.2f °C\n", sensorData.temperature);
    Serial.printf("Humidity: %.2f %%\n", sensorData.humidity);
    Serial.printf("Pressure: %.2f hPa\n", sensorData.pressure);
    Serial.printf("Gas: %.2f KOhms\n", sensorData.gasResistance);
    Serial.printf("Altitude: %.2f m\n", sensorData.altitude);
    Serial.printf("Dew Point: %.2f °C\n", sensorData.dewPoint);
    Serial.printf("Air Quality Index: %.2f (0-100)\n", sensorData.airQualityIndex);
    Serial.printf("Timestamp: %s\n", sensorData.timestamp.c_str());
}

void handleRoot() {
    Serial.println("Root page requested");
    
    if (cachedHTML.isEmpty()) {
        cachedHTML = getHTML();
    }
    server.send(200, "text/html", cachedHTML);
}

void handleData() {
    Serial.println("Data endpoint requested");
    
    server.sendHeader("Access-Control-Allow-Origin", "*");
    server.sendHeader("Access-Control-Allow-Methods", "GET");
    server.sendHeader("Access-Control-Allow-Headers", "Content-Type");
    
    DynamicJsonDocument doc(1024);
    
    doc["temperature"] = sensorData.temperature;
    doc["humidity"] = sensorData.humidity;
    doc["pressure"] = sensorData.pressure;
    doc["gasResistance"] = sensorData.gasResistance;
    doc["altitude"] = sensorData.altitude;
    doc["dewPoint"] = sensorData.dewPoint;
    doc["airQuality"] = sensorData.airQualityIndex;
    doc["timestamp"] = sensorData.timestamp;
    doc["lastUpdate"] = sensorData.lastUpdate;

    String response;
    serializeJson(doc, response);
    server.send(200, "application/json", response);
}

void handleNotFound() {
    Serial.print("Not found: ");
    Serial.println(server.uri());
    server.send(404, "text/plain", "Not Found");
}

float dewPointCalculation(float temperature, float humidity) {
    float a = 17.271;
    float b = 237.7;
    float temp = (a * temperature) / (b + temperature) + log(humidity / 100);
    return (b * temp) / (a - temp);
}

float calculateAirQualityIndex(float gasResistance, float humidity) {
    float gasScore = map(gasResistance, 5, 500, 0, 100);
    gasScore = constrain(gasScore, 0, 100);
    
    float humidityScore = 100 - abs(humidity - 50) * 2;
    humidityScore = constrain(humidityScore, 0, 100);
    
    return gasScore * 0.7 + humidityScore * 0.3; // Weighted score for AQI
}

String getHTML() {
    String html = R"rawliteral(

<!DOCTYPE HTML>
<html lang="en">
<head>
  <title>BME688 Environmental Monitor | Dashboard</title>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <meta name="description" content="Environmental monitoring system using BME688 sensor">
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.4.2/css/all.min.css">
  <style>
    :root {
      --primary-color: #2c3e50;
      --secondary-color: #34495e;
      --accent-color: #3498db;
      --success-color: #27ae60;
      --warning-color: #f39c12;
      --danger-color: #e74c3c;
      --light-color: #ecf0f1;
      --dark-color: #2c3e50;
      --border-radius: 6px;
      --box-shadow: 0 1px 3px rgba(0,0,0,0.12), 0 1px 2px rgba(0,0,0,0.24);
    }

    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      font-family: 'Segoe UI', system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
    }

    body {
      background-color: #f8f9fa;
      color: var(--dark-color);
      margin: 0;
      padding: 0;
      line-height: 1.6;
    }

    /* Header Styles */
    .header {
      background: var(--primary-color);
      color: white;
      padding: 1rem;
      box-shadow: var(--box-shadow);
    }

    .header-container {
      max-width: 1200px;
      margin: 0 auto;
      display: flex;
      justify-content: space-between;
      align-items: center;
      flex-wrap: wrap; /* Allow items to wrap on smaller screens */
      gap: 0.5rem; /* Add some spacing between header elements */
    }

    .header h1 {
      margin: 0;
      font-size: 1.25rem; /* Slightly smaller header on smaller screens */
      font-weight: 500;
      display: flex;
      align-items: center;
      gap: 0.5rem;
    }

    /* Main Content Container */
    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 1rem; /* Reduced padding for smaller screens */
    }

    .dashboard-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: 1rem;
      flex-wrap: wrap; /* Wrap elements on smaller screens */
      gap: 0.5rem; /* Add spacing between header elements */
    }

    .dashboard-title {
      font-size: 1.25rem; /* Slightly smaller title */
      font-weight: 500;
    }

    .sensor-status {
      display: flex;
      align-items: center;
      gap: 0.375rem; /* Reduced spacing */
      font-size: 0.75rem; /* Smaller font size */
    }

    .sensor-status-dot {
      height: 8px; /* Smaller dot */
      width: 8px; /* Smaller dot */
      border-radius: 50%;
      background-color: var(--success-color);
    }

    .sensor-status-dot.calibrating {
      background-color: var(--warning-color);
    }

    .sensor-status-dot.error {
      background-color: var(--danger-color);
    }

    .date-time {
      font-size: 0.75rem; /* Smaller font size */
      color: #666;
      padding: 0.375rem 0.625rem; /* Reduced padding */
      border-radius: var(--border-radius);
      background-color: #fff;
      display: inline-flex;
      align-items: center;
      gap: 0.375rem; /* Reduced spacing */
      box-shadow: var(--box-shadow);
    }

    /* Status Card Styles */
    .status-card {
      background: #ffffff;
      border-radius: var(--border-radius);
      padding: 0.75rem; /* Reduced padding */
      margin-bottom: 1rem;
      display: flex;
      align-items: center;
      box-shadow: var(--box-shadow);
      border-left: 4px solid var(--success-color);
    }

    .status-card.warning {
      border-left: 4px solid var(--warning-color);
    }

    .status-card.danger {
      border-left: 4px solid var(--danger-color);
    }

    .status-card i {
      font-size: 1.25rem; /* Slightly smaller icon */
      margin-right: 0.75rem; /* Reduced margin */
      padding: 0.5rem; /* Reduced padding */
      border-radius: 50%;
      color: var(--success-color);
    }

    .status-card.warning i {
      color: var(--warning-color);
    }

    .status-card.danger i {
      color: var(--danger-color);
    }

    .status-content {
      flex-grow: 1;
    }

    .status-title {
      font-weight: 500;
      font-size: 0.875rem; /* Smaller font size */
      margin-bottom: 0.125rem;
    }

    .status-message {
      color: #666;
      font-size: 0.75rem; /* Smaller font size */
    }

    .action-button {
      background-color: var(--accent-color);
      color: white;
      border: none;
      border-radius: var(--border-radius);
      padding: 0.375rem 0.75rem; /* Reduced padding */
      cursor: pointer;
      font-size: 0.75rem; /* Smaller font size */
      display: flex;
      align-items: center;
      gap: 0.375rem; /* Reduced spacing */
      transition: background-color 0.2s;
    }

    .action-button:hover {
      background-color: #2980b9;
    }

    /* Grid Styles */
    .grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); /* Slightly smaller cards */
      gap: 0.75rem; /* Reduced gap */
    }

    /* Card Styles */
    .card {
      background: #ffffff;
      border-radius: var(--border-radius);
      padding: 1rem; /* Reduced padding */
      box-shadow: var(--box-shadow);
      height: 100%;
    }

    .card-header {
      display: flex;
      align-items: center;
      margin-bottom: 0.75rem; /* Reduced margin */
    }

    .card-icon {
      font-size: 1rem; /* Smaller icon */
      width: 2rem; /* Smaller icon container */
      height: 2rem; /* Smaller icon container */
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 50%;
      margin-right: 0.5rem; /* Reduced margin */
    }

    .card-title {
      font-size: 0.75rem; /* Smaller font size */
      font-weight: 500;
      color: #666;
    }

    .card-value {
      font-size: 1.5rem; /* Slightly smaller value */
      font-weight: 500;
      color: var(--dark-color);
      margin: 0.5rem 0; /* Reduced margin */
      display: flex;
      align-items: baseline;
    }

    .card-unit {
      font-size: 0.75rem; /* Smaller font size */
      color: #666;
      margin-left: 0.125rem;
      font-weight: 400;
    }

    .card-info {
      font-size: 0.625rem; /* Smaller font size */
      color: #666;
      margin-top: 0.125rem;
    }

    .threshold-range {
      display: flex;
      justify-content: space-between;
      margin-top: 0.5rem; /* Reduced margin */
      font-size: 0.625rem; /* Smaller font size */
      color: #666;
    }

    .threshold-range span {
      white-space: nowrap;
    }

    /* Progress Bar Styles */
    .progress-container {
      width: 100%;
      height: 0.375rem; /* Reduced height */
      background-color: #f1f1f1;
      border-radius: 3px;
      margin-top: 0.5rem; /* Reduced margin */
      overflow: hidden;
    }

    .progress-bar {
      height: 100%;
      border-radius: 3px;
      transition: width 0.8s ease, background-color 0.5s ease;
    }

    .progress-label {
      display: flex;
      justify-content: space-between;
      margin-top: 0.25rem; /* Reduced margin */
      font-size: 0.625rem; /* Smaller font size */
      color: #666;
    }

    .card-secondary-value {
      display: flex;
      font-size: 0.75rem; /* Smaller font size */
      color: #666;
      margin-top: 0.25rem; /* Reduced margin */
      justify-content: space-between;
      flex-wrap: wrap; /* Allow wrapping on smaller screens */
      gap: 0.25rem; /* Add spacing between secondary values */
    }

    .card-badge {
      display: inline-block;
      font-size: 0.625rem; /* Smaller font size */
      padding: 0.0625rem 0.375rem; /* Reduced padding */
      border-radius: 20px;
      background-color: #f8f9fa;
      margin-top: 0.375rem; /* Reduced margin */
    }

    .card-badge.good {
      background-color: rgba(39, 174, 96, 0.15);
      color: var(--success-color);
    }

    .card-badge.ok {
      background-color: rgba(243, 156, 18, 0.15);
      color: var(--warning-color);
    }

    .card-badge.bad {
      background-color: rgba(231, 76, 60, 0.15);
      color: var(--danger-color);
    }

    /* Footer Styles */
    .footer {
      background-color: var(--primary-color);
      color: var(--light-color);
      text-align: center;
      padding: 0.75rem; /* Reduced padding */
      margin-top: 1.5rem; /* Reduced margin */
      font-size: 0.625rem; /* Smaller font size */
      display: flex;
      flex-direction: column;
      gap: 0.375rem; /* Reduced spacing */
    }

    /* Custom card colors */
    .temp-icon { background-color: rgba(231, 76, 60, 0.1); color: #e74c3c; }
    .humid-icon { background-color: rgba(52, 152, 219, 0.1); color: #3498db; }
    .pressure-icon { background-color: rgba(155, 89, 182, 0.1); color: #9b59b6; }
    .altitude-icon { background-color: rgba(243, 156, 18, 0.1); color: #f39c12; }
    .aqi-icon { background-color: rgba(26, 188, 156, 0.1); color: #1abc9c; }

    /* Responsive tweaks */
    @media (max-width: 600px) {
      .header-container, .dashboard-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.25rem; /* Further reduced spacing */
      }

      .status-card {
        flex-direction: column;
        align-items: flex-start;
      }

      .status-card i {
        margin-bottom: 0.25rem;
      }

      .card-secondary-value {
        flex-direction: column;
        gap: 0.125rem;
      }

       /* Make the grid a single column on very small screens */
      .grid {
        grid-template-columns: 1fr;
      }
    }
    
    /* Added refresh button styling */
    .refresh-btn-container {
      margin-left: 0.5rem;
    }
  </style>
</head>
<body>
  <div class="header">
    <div class="header-container">
      <h1><i class="fas fa-microchip"></i> BME688 Environmental Monitor</h1>
      <div class="sensor-status">
        <div id="sensor-status-dot" class="sensor-status-dot"></div>
        <span id="sensor-status-text">Connecting...</span>
        <div class="refresh-btn-container">
          <button id="refresh-button" class="action-button">
            <i class="fas fa-sync-alt"></i> Refresh
          </button>
        </div>
      </div>
    </div>
  </div>

  <div class="container">
    <div class="dashboard-header">
      <div class="dashboard-title">Environmental Metrics</div>
      <div class="date-time">
        <i class="far fa-clock"></i>
        <span id="date-time">Loading...</span>
      </div>
    </div>

    <div class="grid">
    
    
         <!-- Added Air Quality card -->
      <div class="card">
        <div class="card-header">
          <div class="card-icon aqi-icon">
            <i class="fas fa-wind"></i>
          </div>
          <div class="card-title">Air Quality</div>
        </div>
        <div class="card-value" id="air-quality">--<span class="card-unit">/100</span></div>
        <div class="card-info">Air Quality Index</div>
        <div class="progress-container">
          <div id="aqi-bar" class="progress-bar" style="width: 0%; background-color: var(--success-color);"></div>
        </div>
        <div class="progress-label">
          <span>0</span>
          <span id="aqi-text">Measuring...</span>
          <span>100</span>
        </div>
        <div class="card-secondary-value">
          <span>Status:</span>
          <span id="aqi-badge" class="card-badge">--</span>
        </div>
      </div>
 
    
    
      <!-- Temperature card -->
      <div class="card">
        <div class="card-header">
          <div class="card-icon temp-icon">
            <i class="fas fa-thermometer-half"></i>
          </div>
          <div class="card-title">Temperature</div>
        </div>
        <div class="card-value" id="temperature">--<span class="card-unit">°C</span></div>
        <div class="card-info">Ambient temperature</div>
        <div class="progress-container">
          <div id="temp-bar" class="progress-bar" style="width: 0%; background-color: var(--success-color);"></div>
        </div>
        <div class="progress-label">
          <span>0°C</span>
          <span id="temp-text">Measuring...</span>
          <span>40°C</span>
        </div>
        <div class="threshold-range">
          <span>Comfort Zone: 18-24°C</span>
        </div>
      </div>
      
      

      <!-- Humidity card -->
      <div class="card">
        <div class="card-header">
          <div class="card-icon humid-icon">
            <i class="fas fa-tint"></i>
          </div>
          <div class="card-title">Humidity</div>
        </div>
        <div class="card-value" id="humidity">--<span class="card-unit">%</span></div>
        <div class="card-info">Relative humidity</div>
        <div class="progress-container">
          <div id="humidity-bar" class="progress-bar" style="width: 0%; background-color: var(--success-color);"></div>
        </div>
        <div class="progress-label">
          <span>0%</span>
          <span id="humidity-text">Measuring...</span>
          <span>100%</span>
        </div>
        <div class="card-secondary-value">
          <span>Dew Point:</span>
          <span id="dew-point">-- °C</span>
        </div>
      </div>

      <!-- Pressure card -->
      <div class="card">
        <div class="card-header">
          <div class="card-icon pressure-icon">
            <i class="fas fa-tachometer-alt"></i>
          </div>
          <div class="card-title">Pressure</div>
        </div>
        <div class="card-value" id="pressure">--<span class="card-unit">hPa</span></div>
        <div class="card-info">Atmospheric pressure</div>
        <div class="progress-container">
          <div id="pressure-bar" class="progress-bar" style="width: 0%; background-color: var(--success-color);"></div>
        </div>
        <div class="progress-label">
          <span>900 hPa</span>
          <span id="pressure-text">Measuring...</span>
          <span>1100 hPa</span>
        </div>
        <div class="card-secondary-value">
          <span>Sea Level:</span>
          <span id="sea-level-pressure">1013.25 hPa</span>
        </div>
      </div>

      <!-- Altitude card -->
      <div class="card">
        <div class="card-header">
          <div class="card-icon altitude-icon">
            <i class="fas fa-mountain"></i>
          </div>
          <div class="card-title">Altitude</div>
        </div>
        <div class="card-value" id="altitude">--<span class="card-unit">m</span></div>
        <div class="card-info">Approximate altitude</div>
        <div class="progress-container">
          <div id="altitude-bar" class="progress-bar" style="width: 0%; background-color: var(--success-color);"></div>
        </div>
        <div class="progress-label">
          <span>0 m</span>
          <span id="altitude-text">Measuring...</span>
          <span>1000 m</span>
        </div>
        <div class="card-secondary-value">
          <span>Reference pressure:</span>
          <span>1013.25 hPa</span>
        </div>
      </div>
      
</div>
  </div>
 
       
  <div class="footer">
    <div>BME688 Environmental Monitor | ESP32</div>
    <div>Last updated: <span id="last-update-time">--</span></div>
  </div>

  <script>
    // Global variables
    const API_URL = '/data';
    const REFRESH_INTERVAL = 5000; // 5 seconds
    let lastUpdateTime = 0;
    let sensorConnected = false;

    // DOM Elements
    const sensorStatusDot = document.getElementById('sensor-status-dot');
    const sensorStatusText = document.getElementById('sensor-status-text');
    const dateTimeElement = document.getElementById('date-time');
    const lastUpdateTimeElement = document.getElementById('last-update-time'); //Keep last update time

    // Card values
    const temperatureElement = document.getElementById('temperature');
    const humidityElement = document.getElementById('humidity');
    const pressureElement = document.getElementById('pressure');
    const altitudeElement = document.getElementById('altitude');
    const airQualityElement = document.getElementById('air-quality');

    // Progress Bar elements
    const tempBar = document.getElementById('temp-bar');
    const humidityBar = document.getElementById('humidity-bar');
    const pressureBar = document.getElementById('pressure-bar');
    const altitudeBar = document.getElementById('altitude-bar');
    const aqiBar = document.getElementById('aqi-bar');

    // Progress text elements
    const tempText = document.getElementById('temp-text');
    const humidityText = document.getElementById('humidity-text');
    const pressureText = document.getElementById('pressure-text');
    const altitudeText = document.getElementById('altitude-text');
    const aqiText = document.getElementById('aqi-text');

    const dewPointElement = document.getElementById('dew-point');
    const seaLevelPressureElement = document.getElementById('sea-level-pressure');
    const aqiBadge = document.getElementById('aqi-badge');

    // Initialize refresh button
    const refreshButton = document.getElementById('refresh-button');
    refreshButton.addEventListener('click', fetchData);

    // Function to update the date and time
    function updateDateTime() {
      const now = new Date();
      const options = {
        weekday: 'long',
        year: 'numeric',
        month: 'long',
        day: 'numeric',
        hour: '2-digit',
        minute: '2-digit',
        second: '2-digit'
      };
      dateTimeElement.textContent = now.toLocaleDateString('en-US', options);
    }

    // Function to update the sensor connection status
    function updateSensorStatus(connected) {
      sensorConnected = connected;

      if (connected) {
        sensorStatusDot.className = 'sensor-status-dot';
        sensorStatusText.textContent = 'Connected';
        refreshButton.disabled = false;
      } else {
        sensorStatusDot.className = 'sensor-status-dot error';
        sensorStatusText.textContent = 'Disconnected';
        refreshButton.disabled = true;
      }
    }

    // Function to format timestamps from the sensor
    function formatTimestamp(timestamp) {
      if (!timestamp) return '--';
      return timestamp;
    }

    // Function to format the last update time
    function formatLastUpdateTime(lastUpdate) {
      if (!lastUpdate) return '--';

      const now = Date.now();
      const diff = now - lastUpdate;

      if (diff < 60000) {
        return `${Math.floor(diff / 1000)} seconds ago`;
      } else if (diff < 3600000) {
        return `${Math.floor(diff / 60000)} minutes ago`;
      } else {
        return `${Math.floor(diff / 3600000)} hours ago`;
      }
    }

    // Function to map a value from one range to another
    function mapValue(value, inMin, inMax, outMin, outMax) {
      return ((value - inMin) * (outMax - outMin)) / (inMax - inMin) + outMin;
    }

    // Function to update the air quality badge
    function updateAirQualityBadge(value) {
      if (value >= 70) {
        aqiBadge.className = 'card-badge good';
        aqiBadge.textContent = 'Good';
      } else if (value >= 50) {
        aqiBadge.className = 'card-badge ok';
        aqiBadge.textContent = 'Moderate';
      } else {
        aqiBadge.className = 'card-badge bad';
        aqiBadge.textContent = 'Poor';
      }
    }

    // Function to update all UI elements with sensor data
    function updateUI(data) {
      if (!data) return;
      
      // Update air quality index
      airQualityElement.textContent = data.airQuality ? data.airQuality.toFixed(1) : '--';
      if (data.airQuality) {
        aqiBar.style.width = `${data.airQuality}%`;
        aqiText.textContent = `${data.airQuality.toFixed(1)}/100`;
        updateAirQualityBadge(data.airQuality);
      }

      // Update temperature
      temperatureElement.textContent = data.temperature ? data.temperature.toFixed(1) : '--';
      if (data.temperature) {
        const tempPercent = mapValue(data.temperature, 0, 40, 0, 100);
        tempBar.style.width = `${tempPercent}%`;
        tempText.textContent = `${data.temperature.toFixed(1)}°C`;
      }

      // Update humidity
      humidityElement.textContent = data.humidity ? data.humidity.toFixed(1) : '--';
      if (data.humidity) {
        humidityBar.style.width = `${data.humidity}%`;
        humidityText.textContent = `${data.humidity.toFixed(1)}%`;
      }
      dewPointElement.textContent = data.dewPoint ? `${data.dewPoint.toFixed(1)} °C` : '-- °C';

      // Update pressure
      pressureElement.textContent = data.pressure ? data.pressure.toFixed(1) : '--';
      if (data.pressure) {
        const pressurePercent = mapValue(data.pressure, 900, 1100, 0, 100);
        pressureBar.style.width = `${pressurePercent}%`;
        pressureText.textContent = `${data.pressure.toFixed(1)} hPa`;
      }

      // Update altitude
      altitudeElement.textContent = data.altitude ? data.altitude.toFixed(1) : '--';
      if (data.altitude) {
        const altitudePercent = mapValue(data.altitude, 0, 1000, 0, 100);
        altitudeBar.style.width = `${altitudePercent}%`;
        altitudeText.textContent = `${data.altitude.toFixed(1)} m`;
      }

      // Update timestamp
      lastUpdateTimeElement.textContent = formatTimestamp(data.timestamp);
    }

    // Function to fetch data from the ESP32
    function fetchData() {
      refreshButton.disabled = true;
      refreshButton.innerHTML = '<i class="fas fa-spinner fa-spin"></i> Refreshing...';

      fetch(API_URL)
        .then(response => {
          if (!response.ok) {
            throw new Error('Network response was not ok');
          }
          return response.json();
        })
        .then(data => {
          updateSensorStatus(true);
          updateUI(data);
          lastUpdateTime = Date.now();
        })
        .catch(error => {
          console.error('Error fetching sensor data:', error);
          updateSensorStatus(false);
          alert("Connection Error: Could not fetch sensor data. Check connection and ESP32.");
        })
        .finally(() => {
          refreshButton.disabled = false;
          refreshButton.innerHTML = '<i class="fas fa-sync-alt"></i> Refresh';
        });
    }

    // Function to start the periodic data updates
    function startPeriodicUpdates() {
      // Update the date and time immediately and every second
      updateDateTime();
      setInterval(updateDateTime, 1000);

      // Fetch data immediately
      fetchData();

      // Set up periodic data fetching
      setInterval(fetchData, REFRESH_INTERVAL);
    }

    // Start the application when the page is loaded
    window.addEventListener('load', startPeriodicUpdates);
  </script>
</body>
</html>

)rawliteral";

    return html;
}

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

366

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

390

391

392

393

394

395

396

397

398

399

400

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

424

425

426

427

428

429

430

431

432

433

434

435

436

437

438

439

440

441

442

443

444

445

446

447

448

449

450

451

452

453

454

455

456

457

458

459

460

461

462

463

464

465

466

467

468

469

470

471

472

473

474

475

476

477

478

479

480

481

482

483

484

485

486

487

488

489

490

491

492

493

494

495

496

497

498

499

500

501

502

503

504

505

506

507

508

509

510

511

512

513

514

515

516

517

518

519

520

521

522

523

524

525

526

527

528

529

530

531

532

533

534

535

536

537

538

539

540

541

542

543

544

545

546

547

548

549

550

551

552

553

554

555

556

557

558

559

560

561

562

563

564

565

566

567

568

569

570

571

572

573

574

575

576

577

578

579

580

581

582

583

584

585

586

587

588

589

590

591

592

593

594

595

596

597

598

599

600

601

602

603

604

605

606

607

608

609

610

611

612

613

614

615

616

617

618

619

620

621

622

623

624

625

626

627

628

629

630

631

632

633

634

635

636

637

638

639

640

641

642

643

644

645

646

647

648

649

650

651

652

653

654

655

656

657

658

659

660

661

662

663

664

665

666

667

668

669

670

671

672

673

674

675

676

677

678

679

680

681

682

683

684

685

686

687

688

689

690

691

692

693

694

695

696

697

698

699

700

701

702

703

704

705

706

707

708

709

710

711

712

713

714

715

716

717

718

719

720

721

722

723

724

725

726

727

728

729

730

731

732

733

734

735

736

737

738

739

740

741

742

743

744

745

746

747

748

749

750

751

752

753

754

755

756

757

758

759

760

761

762

763

764

765

766

767

768

769

770

771

772

773

774

775

776

777

778

779

780

781

782

783

784

785

786

787

788

789

790

791

792

793

794

795

796

797

798

799

800

801

802

803

804

805

806

807

808

809

810

811

812

813

814

815

816

817

818

819

820

821

822

823

824

825

826

827

828

829

830

831

832

833

834

835

836

837

838

839

840

841

842

843

844

845

846

847

848

849

850

851

852

853

854

855

856

857

858

859

860

861

862

863

864

865

866

867

868

869

870

871

872

873

874

875

876

877

878

879

880

881

882

883

884

885

886

887

888

889

890

891

892

893

894

895

896

897

898

899

900

901

902

903

904

905

906

907

908

909

910

911

912

913

914

915

916

917

918

919

920

921

922

923

924

925

926

927

928

929

930

931

932

933

934

935

936

937

938

939

940

941

942

943

944

945

946

947

948

949

950

951

952

953

954

955

956

957

958

959

960

961

962

963

964

965

966

967

968

969

970

971

972

973

974

975

976

977

978

979

980

981

982

983

984

985

986

987

988

989

990

#include <Wire.h>

#include <SPI.h>

#include <Adafruit_Sensor.h>

#include <Adafruit_BME680.h>

#include <WiFi.h>

#include <WebServer.h>

#include <SPIFFS.h>

#include <ArduinoJson.h>

#include <time.h>

#define SEALEVELPRESSURE_HPA (1013.25)

Adafruit_BME680 bme; // I2C

// Environmental data structure

struct SensorData {

float temperature;

float humidity;

float pressure;

float gasResistance;

float altitude;

float dewPoint;

float airQualityIndex;

String timestamp;

unsigned long lastUpdate;

};

SensorData sensorData;

// Replace with your network credentials

const char* ssid = "ESP";

const char* password = "aaaaaaaa";

// Time settings

const char* ntpServer = "pool.ntp.org";

const long gmtOffset_sec = 0;

const int daylightOffset_sec = 3600;

// Create WebServer object on port 80

WebServer server(80);

// Cached HTML content

String cachedHTML;

// Function prototypes

void handleRoot();

void handleNotFound();

void handleData();

void readSensorData();

float calculateAirQualityIndex(float gas, float humidity);

float dewPointCalculation(float temperature, float humidity);

String getTimeString();

void setupTime();

String getHTML();

void reconnectWiFi();

void setup() {

Serial.begin(115200);

delay(100);

Serial.println(F("BME688 Environmental Monitoring System - Initializing..."));

if (!SPIFFS.begin(true)) {

Serial.println("SPIFFS Mount Failed - will use embedded HTML");

} else {

Serial.println("SPIFFS Mounted Successfully");

}

if (!bme.begin()) {

Serial.println("Could not find a valid BME688 sensor, check wiring!");

while (1) {

delay(1000);

}

bme.setTemperatureOversampling(BME680_OS_8X);

bme.setHumidityOversampling(BME680_OS_4X);

bme.setPressureOversampling(BME680_OS_4X);

bme.setIIRFilterSize(BME680_FILTER_SIZE_3);

bme.setGasHeater(320, 150);

Serial.println("BME688 sensor configuration complete");

reconnectWiFi();

setupTime();

server.on("/", HTTP_GET, handleRoot);

server.on("/data", HTTP_GET, handleData);

server.onNotFound(handleNotFound);

server.begin();

Serial.print("Web server started at http://");

Serial.println(WiFi.localIP());

readSensorData();

}

void loop() {

if (WiFi.status() != WL_CONNECTED) {

reconnectWiFi();

}

server.handleClient();

static unsigned long lastReadTime = 0;

if (millis() - lastReadTime > 5000) {

readSensorData();

lastReadTime = millis();

}

void reconnectWiFi() {

if (WiFi.status() != WL_CONNECTED) {

Serial.println("Connecting to WiFi...");

WiFi.begin(ssid, password);

// Wait up to 20 seconds for connection

int timeout = 0;

while (WiFi.status() != WL_CONNECTED && timeout < 40) {

delay(500);

Serial.print(".");

timeout++;

}

if (WiFi.status() == WL_CONNECTED) {

Serial.println("\nWiFi connected!");

Serial.print("IP address: ");

Serial.println(WiFi.localIP());

} else {

Serial.println("\nWiFi connection failed!");

}

void setupTime() {

configTime(gmtOffset_sec, daylightOffset_sec, ntpServer);

struct tm timeinfo;

if (!getLocalTime(&timeinfo)) {

Serial.println("Failed to obtain time from NTP server");

}

String getTimeString() {

struct tm timeinfo;

if (!getLocalTime(&timeinfo)) {

return "Time not available";

}

char timeStr[20];

strftime(timeStr, sizeof(timeStr), "%Y-%m-%d %H:%M:%S", &timeinfo);

return String(timeStr);

}

void readSensorData() {

unsigned long endTime = bme.beginReading();

if (endTime == 0) {

Serial.println("Failed to begin reading :(");

return;

}

delay(50); // Allow time for measurement

if (!bme.endReading()) {

Serial.println("Failed to complete reading :(");

return;

}

sensorData.temperature = bme.temperature;

sensorData.humidity = bme.humidity;

sensorData.pressure = bme.pressure / 100.0F;

sensorData.gasResistance = bme.gas_resistance / 1000.0;

sensorData.altitude = bme.readAltitude(SEALEVELPRESSURE_HPA);

sensorData.dewPoint = dewPointCalculation(sensorData.temperature, sensorData.humidity);

sensorData.airQualityIndex = calculateAirQualityIndex(sensorData.gasResistance, sensorData.humidity);

sensorData.timestamp = getTimeString();

sensorData.lastUpdate = millis();

Serial.println("New Sensor Readings:");

Serial.printf("Temperature: %.2f °C\n", sensorData.temperature);

Serial.printf("Humidity: %.2f %%\n", sensorData.humidity);

Serial.printf("Pressure: %.2f hPa\n", sensorData.pressure);

Serial.printf("Gas: %.2f KOhms\n", sensorData.gasResistance);

Serial.printf("Altitude: %.2f m\n", sensorData.altitude);

Serial.printf("Dew Point: %.2f °C\n", sensorData.dewPoint);

Serial.printf("Air Quality Index: %.2f (0-100)\n", sensorData.airQualityIndex);

Serial.printf("Timestamp: %s\n", sensorData.timestamp.c_str());

}

void handleRoot() {

Serial.println("Root page requested");

if (cachedHTML.isEmpty()) {

cachedHTML = getHTML();

}

server.send(200, "text/html", cachedHTML);

}

void handleData() {

Serial.println("Data endpoint requested");

server.sendHeader("Access-Control-Allow-Origin", "*");

server.sendHeader("Access-Control-Allow-Methods", "GET");

server.sendHeader("Access-Control-Allow-Headers", "Content-Type");

DynamicJsonDocument doc(1024);

doc["temperature"] = sensorData.temperature;

doc["humidity"] = sensorData.humidity;

doc["pressure"] = sensorData.pressure;

doc["gasResistance"] = sensorData.gasResistance;

doc["altitude"] = sensorData.altitude;

doc["dewPoint"] = sensorData.dewPoint;

doc["airQuality"] = sensorData.airQualityIndex;

doc["timestamp"] = sensorData.timestamp;

doc["lastUpdate"] = sensorData.lastUpdate;

String response;

serializeJson(doc, response);

server.send(200, "application/json", response);

}

void handleNotFound() {

Serial.print("Not found: ");

Serial.println(server.uri());

server.send(404, "text/plain", "Not Found");

}

float dewPointCalculation(float temperature, float humidity) {

float a = 17.271;

float b = 237.7;

float temp = (a * temperature) / (b + temperature) + log(humidity / 100);

return (b * temp) / (a - temp);

}

float calculateAirQualityIndex(float gasResistance, float humidity) {

float gasScore = map(gasResistance, 5, 500, 0, 100);

gasScore = constrain(gasScore, 0, 100);

float humidityScore = 100 - abs(humidity - 50) * 2;

humidityScore = constrain(humidityScore, 0, 100);

return gasScore * 0.7 + humidityScore * 0.3; // Weighted score for AQI

}

String getHTML() {

String html = R"rawliteral(

<!DOCTYPE HTML>

<head>

<title>BME688 Environmental Monitor | Dashboard</title>

<style>

:root {

--primary-color: #2c3e50;

--secondary-color: #34495e;

--accent-color: #3498db;

--success-color: #27ae60;

--warning-color: #f39c12;

--danger-color: #e74c3c;

--light-color: #ecf0f1;

--dark-color: #2c3e50;

--border-radius: 6px;

--box-shadow: 0 1px 3px rgba(0,0,0,0.12), 0 1px 2px rgba(0,0,0,0.24);

}

* {

box-sizing: border-box;

margin: 0;

padding: 0;

font-family: 'Segoe UI', system-ui, -apple-system, BlinkMacSystemFont, sans-serif;

}

body {

background-color: #f8f9fa;

color: var(--dark-color);

margin: 0;

padding: 0;

line-height: 1.6;

}

/* Header Styles */

.header {

background: var(--primary-color);

color: white;

padding: 1rem;

box-shadow: var(--box-shadow);

}

.header-container {

max-width: 1200px;

margin: 0 auto;

display: flex;

justify-content: space-between;

align-items: center;

flex-wrap: wrap; /* Allow items to wrap on smaller screens */

gap: 0.5rem; /* Add some spacing between header elements */

}

.header h1 {

margin: 0;

font-size: 1.25rem; /* Slightly smaller header on smaller screens */

font-weight: 500;

display: flex;

align-items: center;

gap: 0.5rem;

}

/* Main Content Container */

.container {

max-width: 1200px;

margin: 0 auto;

padding: 1rem; /* Reduced padding for smaller screens */

}

.dashboard-header {

display: flex;

justify-content: space-between;

align-items: center;

margin-bottom: 1rem;

flex-wrap: wrap; /* Wrap elements on smaller screens */

gap: 0.5rem; /* Add spacing between header elements */

}

.dashboard-title {

font-size: 1.25rem; /* Slightly smaller title */

font-weight: 500;

}

.sensor-status {

display: flex;

align-items: center;

gap: 0.375rem; /* Reduced spacing */

font-size: 0.75rem; /* Smaller font size */

}

.sensor-status-dot {

height: 8px; /* Smaller dot */

width: 8px; /* Smaller dot */

border-radius: 50%;

background-color: var(--success-color);

}

.sensor-status-dot.calibrating {

background-color: var(--warning-color);

}

.sensor-status-dot.error {

background-color: var(--danger-color);

}

.date-time {

font-size: 0.75rem; /* Smaller font size */

color: #666;

padding: 0.375rem 0.625rem; /* Reduced padding */

border-radius: var(--border-radius);

background-color: #fff;

display: inline-flex;

align-items: center;

gap: 0.375rem; /* Reduced spacing */

box-shadow: var(--box-shadow);

}

/* Status Card Styles */

.status-card {

background: #ffffff;

border-radius: var(--border-radius);

padding: 0.75rem; /* Reduced padding */

margin-bottom: 1rem;

display: flex;

align-items: center;

box-shadow: var(--box-shadow);

border-left: 4px solid var(--success-color);

}

.status-card.warning {

border-left: 4px solid var(--warning-color);

}

.status-card.danger {

border-left: 4px solid var(--danger-color);

}

.status-card i {

font-size: 1.25rem; /* Slightly smaller icon */

margin-right: 0.75rem; /* Reduced margin */

padding: 0.5rem; /* Reduced padding */

border-radius: 50%;

color: var(--success-color);

}

.status-card.warning i {

color: var(--warning-color);

}

.status-card.danger i {

color: var(--danger-color);

}

.status-content {

flex-grow: 1;

}

.status-title {

font-weight: 500;

font-size: 0.875rem; /* Smaller font size */

margin-bottom: 0.125rem;

}

.status-message {

color: #666;

font-size: 0.75rem; /* Smaller font size */

}

.action-button {

background-color: var(--accent-color);

color: white;

border: none;

border-radius: var(--border-radius);

padding: 0.375rem 0.75rem; /* Reduced padding */

cursor: pointer;

font-size: 0.75rem; /* Smaller font size */

display: flex;

align-items: center;

gap: 0.375rem; /* Reduced spacing */

transition: background-color 0.2s;

}

.action-button:hover {

background-color: #2980b9;

}

/* Grid Styles */

.grid {

display: grid;

grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); /* Slightly smaller cards */

gap: 0.75rem; /* Reduced gap */

}

/* Card Styles */

.card {

background: #ffffff;

border-radius: var(--border-radius);

padding: 1rem; /* Reduced padding */

box-shadow: var(--box-shadow);

height: 100%;

}

.card-header {

display: flex;

align-items: center;

margin-bottom: 0.75rem; /* Reduced margin */

}

.card-icon {

font-size: 1rem; /* Smaller icon */

width: 2rem; /* Smaller icon container */

height: 2rem; /* Smaller icon container */

display: flex;

align-items: center;

justify-content: center;

border-radius: 50%;

margin-right: 0.5rem; /* Reduced margin */

}

.card-title {

font-size: 0.75rem; /* Smaller font size */

font-weight: 500;

color: #666;

}

.card-value {

font-size: 1.5rem; /* Slightly smaller value */

font-weight: 500;

color: var(--dark-color);

margin: 0.5rem 0; /* Reduced margin */

display: flex;

align-items: baseline;

}

.card-unit {

font-size: 0.75rem; /* Smaller font size */

color: #666;

margin-left: 0.125rem;

font-weight: 400;

}

.card-info {

font-size: 0.625rem; /* Smaller font size */

color: #666;

margin-top: 0.125rem;

}

.threshold-range {

display: flex;

justify-content: space-between;

margin-top: 0.5rem; /* Reduced margin */

font-size: 0.625rem; /* Smaller font size */

color: #666;

}

.threshold-range span {

white-space: nowrap;

}

/* Progress Bar Styles */

.progress-container {

width: 100%;

height: 0.375rem; /* Reduced height */

background-color: #f1f1f1;

border-radius: 3px;

margin-top: 0.5rem; /* Reduced margin */

overflow: hidden;

}

.progress-bar {

height: 100%;

border-radius: 3px;

transition: width 0.8s ease, background-color 0.5s ease;

}

.progress-label {

display: flex;

justify-content: space-between;

margin-top: 0.25rem; /* Reduced margin */

font-size: 0.625rem; /* Smaller font size */

color: #666;

}

.card-secondary-value {

display: flex;

font-size: 0.75rem; /* Smaller font size */

color: #666;

margin-top: 0.25rem; /* Reduced margin */

justify-content: space-between;

flex-wrap: wrap; /* Allow wrapping on smaller screens */

gap: 0.25rem; /* Add spacing between secondary values */

}

.card-badge {

display: inline-block;

font-size: 0.625rem; /* Smaller font size */

padding: 0.0625rem 0.375rem; /* Reduced padding */

border-radius: 20px;

background-color: #f8f9fa;

margin-top: 0.375rem; /* Reduced margin */

}

.card-badge.good {

background-color: rgba(39, 174, 96, 0.15);

color: var(--success-color);

}

.card-badge.ok {

background-color: rgba(243, 156, 18, 0.15);

color: var(--warning-color);

}

.card-badge.bad {

background-color: rgba(231, 76, 60, 0.15);

color: var(--danger-color);

}

/* Footer Styles */

.footer {

background-color: var(--primary-color);

color: var(--light-color);

text-align: center;

padding: 0.75rem; /* Reduced padding */

margin-top: 1.5rem; /* Reduced margin */

font-size: 0.625rem; /* Smaller font size */

display: flex;

flex-direction: column;

gap: 0.375rem; /* Reduced spacing */

}

/* Custom card colors */

.temp-icon { background-color: rgba(231, 76, 60, 0.1); color: #e74c3c; }

.humid-icon { background-color: rgba(52, 152, 219, 0.1); color: #3498db; }

.pressure-icon { background-color: rgba(155, 89, 182, 0.1); color: #9b59b6; }

.altitude-icon { background-color: rgba(243, 156, 18, 0.1); color: #f39c12; }

.aqi-icon { background-color: rgba(26, 188, 156, 0.1); color: #1abc9c; }

/* Responsive tweaks */

@media (max-width: 600px) {

.header-container, .dashboard-header {

flex-direction: column;

align-items: flex-start;

gap: 0.25rem; /* Further reduced spacing */

}

.status-card {

flex-direction: column;

align-items: flex-start;

}

.status-card i {

margin-bottom: 0.25rem;

}

.card-secondary-value {

flex-direction: column;

gap: 0.125rem;

}

/* Make the grid a single column on very small screens */

.grid {

grid-template-columns: 1fr;

}

/* Added refresh button styling */

.refresh-btn-container {

margin-left: 0.5rem;

}

</style>

</head>

<body>

<h1><i class="fas fa-microchip"></i> BME688 Environmental Monitor</h1>

<span id="sensor-status-text">Connecting...</span>

<i class="fas fa-sync-alt"></i> Refresh

</button>

</div>

<div class="dashboard-title">Environmental Metrics</div>

<span id="date-time">Loading...</span>

</div>

</div>

<div class="card-title">Air Quality</div>

</div>

<div class="card-info">Air Quality Index</div>

</div>

<span id="aqi-text">Measuring...</span>

</div>

<span>Status:</span>

</div>

</div>

<div class="card-title">Temperature</div>

</div>

<div class="card-info">Ambient temperature</div>

</div>

<span id="temp-text">Measuring...</span>

</div>

<span>Comfort Zone: 18-24°C</span>

</div>

</div>

<div class="card-title">Humidity</div>

</div>

<div class="card-info">Relative humidity</div>

</div>

<span id="humidity-text">Measuring...</span>

</div>

<span>Dew Point:</span>

</div>

</div>

<div class="card-title">Pressure</div>

</div>

<div class="card-info">Atmospheric pressure</div>

</div>

<span id="pressure-text">Measuring...</span>

</div>

<span>Sea Level:</span>

</div>

</div>

<div class="card-title">Altitude</div>

</div>

<div class="card-info">Approximate altitude</div>

</div>

<span id="altitude-text">Measuring...</span>

</div>

<span>Reference pressure:</span>

</div>

<div>BME688 Environmental Monitor | ESP32</div>

<div>Last updated: <span id="last-update-time">--</span></div>

</div>

// Global variables

const API_URL = '/data';

const REFRESH_INTERVAL = 5000; // 5 seconds

let lastUpdateTime = 0;

let sensorConnected = false;

// DOM Elements

const sensorStatusDot = document.getElementById('sensor-status-dot');

const sensorStatusText = document.getElementById('sensor-status-text');

const dateTimeElement = document.getElementById('date-time');

const lastUpdateTimeElement = document.getElementById('last-update-time'); //Keep last update time

// Card values

const temperatureElement = document.getElementById('temperature');

const humidityElement = document.getElementById('humidity');

const pressureElement = document.getElementById('pressure');

const altitudeElement = document.getElementById('altitude');

const airQualityElement = document.getElementById('air-quality');

// Progress Bar elements

const tempBar = document.getElementById('temp-bar');

const humidityBar = document.getElementById('humidity-bar');

const pressureBar = document.getElementById('pressure-bar');

const altitudeBar = document.getElementById('altitude-bar');

const aqiBar = document.getElementById('aqi-bar');

// Progress text elements

const tempText = document.getElementById('temp-text');

const humidityText = document.getElementById('humidity-text');

const pressureText = document.getElementById('pressure-text');

const altitudeText = document.getElementById('altitude-text');

const aqiText = document.getElementById('aqi-text');

const dewPointElement = document.getElementById('dew-point');

const seaLevelPressureElement = document.getElementById('sea-level-pressure');

const aqiBadge = document.getElementById('aqi-badge');

// Initialize refresh button

const refreshButton = document.getElementById('refresh-button');

refreshButton.addEventListener('click', fetchData);

// Function to update the date and time

function updateDateTime() {

const now = new Date();

const options = {

weekday: 'long',

year: 'numeric',

month: 'long',

day: 'numeric',

hour: '2-digit',

minute: '2-digit',

second: '2-digit'

};

dateTimeElement.textContent = now.toLocaleDateString('en-US', options);

}

// Function to update the sensor connection status

function updateSensorStatus(connected) {

sensorConnected = connected;

if (connected) {

sensorStatusDot.className = 'sensor-status-dot';

sensorStatusText.textContent = 'Connected';

refreshButton.disabled = false;

} else {

sensorStatusDot.className = 'sensor-status-dot error';

sensorStatusText.textContent = 'Disconnected';

refreshButton.disabled = true;

}

// Function to format timestamps from the sensor

function formatTimestamp(timestamp) {

if (!timestamp) return '--';

return timestamp;

}

// Function to format the last update time

function formatLastUpdateTime(lastUpdate) {

if (!lastUpdate) return '--';

const now = Date.now();

const diff = now - lastUpdate;

if (diff < 60000) {

return `${Math.floor(diff / 1000)} seconds ago`;

} else if (diff < 3600000) {

return `${Math.floor(diff / 60000)} minutes ago`;

} else {

return `${Math.floor(diff / 3600000)} hours ago`;

}

// Function to map a value from one range to another

function mapValue(value, inMin, inMax, outMin, outMax) {

return ((value - inMin) * (outMax - outMin)) / (inMax - inMin) + outMin;

}

// Function to update the air quality badge

function updateAirQualityBadge(value) {

if (value >= 70) {

aqiBadge.className = 'card-badge good';

aqiBadge.textContent = 'Good';

} else if (value >= 50) {

aqiBadge.className = 'card-badge ok';

aqiBadge.textContent = 'Moderate';

} else {

aqiBadge.className = 'card-badge bad';

aqiBadge.textContent = 'Poor';

}

// Function to update all UI elements with sensor data

function updateUI(data) {

if (!data) return;

// Update air quality index

airQualityElement.textContent = data.airQuality ? data.airQuality.toFixed(1) : '--';

if (data.airQuality) {

aqiBar.style.width = `${data.airQuality}%`;

aqiText.textContent = `${data.airQuality.toFixed(1)}/100`;

updateAirQualityBadge(data.airQuality);

}

// Update temperature

temperatureElement.textContent = data.temperature ? data.temperature.toFixed(1) : '--';

if (data.temperature) {

const tempPercent = mapValue(data.temperature, 0, 40, 0, 100);

tempBar.style.width = `${tempPercent}%`;

tempText.textContent = `${data.temperature.toFixed(1)}°C`;

}

// Update humidity

humidityElement.textContent = data.humidity ? data.humidity.toFixed(1) : '--';

if (data.humidity) {

humidityBar.style.width = `${data.humidity}%`;

humidityText.textContent = `${data.humidity.toFixed(1)}%`;

}

dewPointElement.textContent = data.dewPoint ? `${data.dewPoint.toFixed(1)} °C` : '-- °C';

// Update pressure

pressureElement.textContent = data.pressure ? data.pressure.toFixed(1) : '--';

if (data.pressure) {

const pressurePercent = mapValue(data.pressure, 900, 1100, 0, 100);

pressureBar.style.width = `${pressurePercent}%`;

pressureText.textContent = `${data.pressure.toFixed(1)} hPa`;

}

// Update altitude

altitudeElement.textContent = data.altitude ? data.altitude.toFixed(1) : '--';

if (data.altitude) {

const altitudePercent = mapValue(data.altitude, 0, 1000, 0, 100);

altitudeBar.style.width = `${altitudePercent}%`;

altitudeText.textContent = `${data.altitude.toFixed(1)} m`;

}

// Update timestamp

lastUpdateTimeElement.textContent = formatTimestamp(data.timestamp);

}

// Function to fetch data from the ESP32

function fetchData() {

refreshButton.disabled = true;

refreshButton.innerHTML = '<i class="fas fa-spinner fa-spin"></i> Refreshing...';

fetch(API_URL)

.then(response => {

if (!response.ok) {

throw new Error('Network response was not ok');

}

return response.json();

})

.then(data => {

updateSensorStatus(true);

updateUI(data);

lastUpdateTime = Date.now();

})

.catch(error => {

console.error('Error fetching sensor data:', error);

updateSensorStatus(false);

alert("Connection Error: Could not fetch sensor data. Check connection and ESP32.");

})

.finally(() => {

refreshButton.disabled = false;

refreshButton.innerHTML = '<i class="fas fa-sync-alt"></i> Refresh';

});

}

// Function to start the periodic data updates

function startPeriodicUpdates() {

// Update the date and time immediately and every second

updateDateTime();

setInterval(updateDateTime, 1000);

// Fetch data immediately

fetchData();

// Set up periodic data fetching

setInterval(fetchData, REFRESH_INTERVAL);

}

// Start the application when the page is loaded

window.addEventListener('load', startPeriodicUpdates);

</script>

</body>

</html>

)rawliteral";

return html;

}

Upload the code to ESP32 using Arduino IDE.
Open Serial Monitor (Baud Rate: 115200).
Check IP Address (e.g., 192.168.81.238).

Sensor Configuration

The BME688 is initialized with specific settings to optimize its performance:

bme.setTemperatureOversampling(BME680_OS_8X);
bme.setHumidityOversampling(BME680_OS_4X);
bme.setPressureOversampling(BME680_OS_4X);
bme.setIIRFilterSize(BME680_FILTER_SIZE_3);
bme.setGasHeater(320, 150); // 320°C for 150ms

bme.setTemperatureOversampling(BME680_OS_8X);

bme.setHumidityOversampling(BME680_OS_4X);

bme.setPressureOversampling(BME680_OS_4X);

bme.setIIRFilterSize(BME680_FILTER_SIZE_3);

bme.setGasHeater(320, 150); // 320°C for 150ms

These settings provide a good balance between accuracy and power consumption.

Data Collection and Processing

The system collects raw sensor data and then processes it to derive valuable metrics:

Dew Point Calculation

float dewPointCalculation(float temperature, float humidity) {
float a = 17.271;
float b = 237.7;
float temp = (a * temperature) / (b + temperature) + log(humidity / 100);
return (b * temp) / (a - temp);
}

float dewPointCalculation(float temperature, float humidity) {

float a = 17.271;

float b = 237.7;

float temp = (a * temperature) / (b + temperature) + log(humidity / 100);

return (b * temp) / (a - temp);

}

Air Quality Index

float calculateAirQualityIndex(float gasResistance, float humidity) {
float gasScore = map(gasResistance, 5, 500, 0, 100);
gasScore = constrain(gasScore, 0, 100);

float humidityScore = 100 - abs(humidity - 50) * 2;
humidityScore = constrain(humidityScore, 0, 100);

return gasScore * 0.7 + humidityScore * 0.3; // Weighted score for AQI
}

float calculateAirQualityIndex(float gasResistance, float humidity) {

float gasScore = map(gasResistance, 5, 500, 0, 100);

gasScore = constrain(gasScore, 0, 100);

float humidityScore = 100 - abs(humidity - 50) * 2;

humidityScore = constrain(humidityScore, 0, 100);

return gasScore * 0.7 + humidityScore * 0.3; // Weighted score for AQI

}

This calculation creates a 0-100 scale where higher values indicate better air quality.

The project has a web dashboard built with HTML, CSS, and JavaScript. The interface displays:

Real-time sensor readings
Visual indicators for each metric
Progress bars showing values about normal ranges
Connection status and timestamp information

Testing IoT Air Quality & Weather Monitoring ESP32 BME688

Open a web browser and enter the ESP32’s IP address.
The webpage will display temperature, humidity, pressure, and air quality data.

This is how we can interface the BME688 Environmental Sensor with ESP32 or ESP8266 WiFi module to measure IAQ (Indoor Air Quality) and other environmental parameters, detect harmful gases, measure IAQ, and estimate CO2 levels. This makes it ideal for home automation, IoT, and weather monitoring applications.

IoT Air Quality & Weather Monitoring with ESP32 & BME688

DIY ESP32 Thermal Camera with MLX90640 and TFT Display

IoT Based ESP32 Prepaid Energy Meter with PZEM-004T | Power Monitoring & Web Control

Step-by-Step: Build an IoT Energy Meter with ESP32 & PZEM-004T V3 (TFT + Web Dashboard)

IoT Based Fire and Smoke Detection System with Alert Notifications Using ESP32

Interfacing ZMPT101B Voltage Sensor with ESP32

Getting Started with ESP32 UWB DW3000 Board Ultra-Wideband

DIY ESP32 Thermal Camera with MLX90640 and TFT Display

IoT Based ESP32 Prepaid Energy Meter with PZEM-004T | Power Monitoring & Web Control

Step-by-Step: Build an IoT Energy Meter with ESP32 & PZEM-004T V3 (TFT + Web Dashboard)

IoT Air Quality & Weather Monitoring with ESP32 & BME688

Quick Links

Company

Services

Ads Blocker Detected!!!

Ads Blocker Detected!!!

IoT Air Quality & Weather Monitoring with ESP32 & BME688

Components Required

BME688 Temperature, Humidity, Pressure, and Gas Sensor

BME688 Pinout & Wiring

Wiring: ESP32 & BME688 Sensor

Programming ESP32 for BME688

Required Libraries

Installing Libraries in Arduino IDE

Source Code – BME688 IoT Air Quality & Weather Monitoring with ESP32

Data Collection and Processing

Related Posts

Quick Links

Company

Services

Subscribe to Updates

Ads Blocker Detected!!!

Ads Blocker Detected!!!