Wokwi - Online ESP32, STM32, Arduino Simulator

#include <WiFi.h>

// Replace with your network credentials
const char* ssid = "Wokwi-GUEST";
const char* 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 outputState = "off";

// Assign output variable to GPIO 2
const int output = 2;

void setup() {
  Serial.begin(115200);
  // Initialize the output variable as an output
  pinMode(output, OUTPUT);
  // Set output to LOW
  digitalWrite(output, LOW);

  // Connect to Wi-Fi network
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected.");
  
  // Start the server
  server.begin();
  Serial.println("Server started");

  // Print the IP address
  Serial.print("Use this URL to connect: ");
  Serial.print("http://");
  Serial.print(WiFi.localIP());
  Serial.println("/");
}

void loop() {
  WiFiClient client = server.available();   // Listen for incoming clients

  if (client) {                             // If a new client connects,
    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()) {            // loop while the client's connected
      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();

            // Display the HTML web page
            client.println("<!DOCTYPE html><html>");
            client.println("<head><title>ESP32 LED Control</title></head>");
            client.println("<body><h1>ESP32 LED Control</h1>");
            client.println("<p>Click to turn the LED on or off.</p>");
            client.println("<p><a href=\"/H\"><button>ON</button></a></p>");
            client.println("<p><a href=\"/L\"><button>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
        }
        
        // Check to see if the client request was "GET /H" or "GET /L":
        if (header.indexOf("GET /H") >= 0) {
          Serial.println("LED ON");
          outputState = "on";
          digitalWrite(output, HIGH);
        } else if (header.indexOf("GET /L") >= 0) {
          Serial.println("LED OFF");
          outputState = "off";
          digitalWrite(output, LOW);
        }
      }
    }
    // Clear the header variable
    header = "";
    // Close the connection
    client.stop();
    Serial.println("Client disconnected.");
    Serial.println("");
  }
}