ESP32 Web Server - Room Monitoring and Controlling System

Hello! This week's blog is the last blog for my Embedded Systems projects :'( In this post, I will talk about ESP32 Web Server and how to implement it by making a room monitoring and controlling system that can monitor the temperature in the room and turn on or off the cooling fan from a distance by using a browser.

First, let's prepare the components you'll need:

1. ESP32

2. Breadboard

3. LED

4. 330-ohm resistors

5. Male-to-male jumpers

6. BMP280

7. Laptop/PC

8. Micro USB

This is the circuit I made:

Now, make sure you have the right libraries. You can check my blog post when I explained about BMP280 sensor. After you're done installing it, let's follow these steps:

1. Open Arduino IDE

2. Copy this code, but don't upload it yet! You have to make some adjustments that I'll explain below

// Load Wi-Fi library
#include <WiFi.h>
#include <Wire.h>
#include <SPI.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BMP280.h>
#define BMP_SCK (13)
#define BMP_MISO (12)
#define BMP_MOSI (11)
#define BMP_CS (10)
#define SEALEVELPRESSURE_HPA (1013.25)
Adafruit_BMP280 bmp; // I2C
// Replace with your network credentials
const char* ssid = "REPLACE_WITH_YOUR_SSID";
const char* password = "REPLACE_WITH_YOUR_PASSWORD";
// Set web server port number to 80
WiFiServer server(80);
// Variable to store the HTTP request
String header;
// Auxiliar variables to store the current output state
String outputLEDState = "off";
// Assign output variables to GPIO pins
const int outputLED = 23;
// Current time
unsigned long currentTime = millis();
// Previous time
unsigned long previousTime = 0;
// Define timeout time in milliseconds (example: 2000ms = 2s)
const long timeoutTime = 2000;
void setup() {
Serial.begin(115200);
while ( !Serial ) delay(100);

// Initialize the output variables as outputs
pinMode(outputLED, OUTPUT);
// Set outputs to LOW
digitalWrite(outputLED, LOW);
// setting bmp280
if (!bmp.begin(0x76)) {
Serial.println("Could not find a valid BMP280 sensor, check wiring!");
while (1);
}
// Default settings from datasheet.
bmp.setSampling(Adafruit_BMP280::MODE_NORMAL, /* Operating Mode. */
Adafruit_BMP280::SAMPLING_X2, /* Temp. oversampling */
Adafruit_BMP280::SAMPLING_X16, /* Pressure oversampling */
Adafruit_BMP280::FILTER_X16, /* Filtering. */
Adafruit_BMP280::STANDBY_MS_500); /* Standby time. */
// Connect to Wi-Fi network with SSID and password
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
// Print local IP address and start web server
Serial.println("");
Serial.println("WiFi connected.");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
server.begin();
}
void loop(){
WiFiClient client = server.available(); // Listen for incoming clients
if (client) { // If a new client connects,
currentTime = millis();
previousTime = currentTime;
Serial.println("New Client."); // print a message out in the serial port
String currentLine = ""; // make a String to hold incoming data from the client
while (client.connected() && currentTime - previousTime <= timeoutTime) { // loop while the client's connected
currentTime = millis();
if (client.available()) { // if there's bytes to read from the client,
char c = client.read(); // read a byte, then
Serial.write(c); // print it out the serial monitor
header += c;
if (c == '\n') { // if the byte is a newline character
// if the current line is blank, you got two newline characters in a row.
// that's the end of the client HTTP request, so send a response:
if (currentLine.length() == 0) {
// HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
// and a content-type so the client knows what's coming, then a blank line:
client.println("HTTP/1.1 200 OK");
client.println("Content-type:text/html");
client.println("Connection: close");
client.println();

// turns the GPIOs on and off
if (header.indexOf("GET /LED/on")>= 0) {
Serial.println("Fan is on");
outputLEDState = "on";
digitalWrite(outputLED, HIGH);
} else if (header.indexOf("GET /LED/off") >= 0) {
Serial.println("Fan is off");
outputLEDState = "off";
digitalWrite(outputLED, LOW);
}

// Display the HTML web page
client.println("<!DOCTYPE html><html>");
client.println("<head><meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">");
client.println("<link rel=\"icon\" href=\"data:,\">");

// CSS to style the table
client.println("<style>body { text-align: center; font-family: \"Trebuchet MS\", Arial;}");
client.println("table { border-collapse: collapse; width:35%; margin-left:auto; margin-right:auto; }");
client.println("th { padding: 12px; background-color: #58c6cc; color: white; }");
client.println("tr { border: 1px solid #ddd; padding: 12px; }");
client.println("tr:hover { background-color: #bcbcbc; }");
client.println("td { border: none; padding: 12px; }");
client.println(".sensor { color:white; font-weight: bold; background-color: #bcbcbc; padding: 1px; }");
// CSS to style the on/off buttons
client.println("<style>html { font-family: Helvetica; display: inline-block; margin: 0px auto; text-align: center;}");
client.println(".button { background-color: #4CAF50; border: none; color: white; padding: 16px 40px;");
client.println("text-decoration: none; font-size: 30px; margin: 2px; cursor: pointer;}");
client.println(".button2 {background-color: #ff0000;}</style></head>");

// Web Page Heading
client.println("</style></head><body><h1>Room Monitoring and Controlling System</h1>");
// table
client.println("<table><tr><th>MEASUREMENT</th><th>VALUE</th></tr>");
client.println("<tr><td>Temp. Celsius</td><td><span class=\"sensor\">");
client.println(bmp.readTemperature());
client.println(" *C</span></td></tr>");
client.println("<tr><td>Temp. Fahrenheit</td><td><span class=\"sensor\">");
client.println(1.8 * bmp.readTemperature() + 32);
client.println(" *F</span></td></tr>");
client.println("<tr><td>Pressure</td><td><span class=\"sensor\">");
client.println(bmp.readPressure() / 100.0F);
client.println(" hPa</span></td></tr>");
client.println("<tr><td>Approx. Altitude</td><td><span class=\"sensor\">");
client.println(bmp.readAltitude(SEALEVELPRESSURE_HPA));
client.println(" m</span></td></tr>");
client.println("</body></html>");

// Display current state, and ON/OFF buttons for GPIO 23
client.println("<p>Fan is " + outputLEDState + "</p>");
// If the outputLED is off, it displays the OFF button
if (outputLEDState=="off") {
client.println("<p><a href=\"/LED/on\"><button class=\"button\">ON</button></a></p>");
} else {
client.println("<p><a href=\"/LED/off\"><button class=\"button button2\">OFF</button></a></p>");
}

client.println("</body></html>");

// The HTTP response ends with another blank line
client.println();
// Break out of the while loop
break;
} else { // if you got a newline, then clear currentLine
currentLine = "";
}
} else if (c != '\r') { // if you got anything else but a carriage return character,
currentLine += c; // add it to the end of the currentLine
}
}
}
// Clear the header variable
header = "";
// Close the connection
client.stop();
Serial.println("Client disconnected.");
Serial.println("");
}
}

3. Change these lines in your code with your network credentials. ssid is your Wi-Fi name and password is your Wi-Fi password.

// Replace with your network credentials

const char* ssid = "REPLACE_WITH_YOUR_SSID";

const char* password = "REPLACE_WITH_YOUR_PASSWORD";

4. Connect your ESP32 board with your computer.