Wokwi - Online ESP32, STM32, Arduino Simulator

#include <WiFi.h>
#include <WiFiClient.h>
#include <WebServer.h>
#include <uri/UriBraces.h>

#define WIFI_SSID "Atharva's Galaxy"
#define WIFI_PASSWORD "samsungS24"
// Defining the WiFi channel speeds up the connection:
#define WIFI_CHANNEL 6

WebServer server(80);

// Original pins (kept for compatibility)
const int LED1 = 19; // repurposed for RELAY by default
const int LED2 = 27; // stays as a regular LED

// Relay configuration (uses LED1 pin by default)
const int RELAY_PIN = LED1; // change this if your relay is wired to other GPIO
const bool RELAY_ACTIVE_LOW = true; // set to false if your relay activates on HIGH

bool led1State = false; // used as relay state (false = off, true = on)
bool led2State = false;

void applyRelayOutput() {
  // Drive the relay pin according to led1State and whether it's active-low
  if (RELAY_ACTIVE_LOW) {
    // ON  -> LOW, OFF -> HIGH
    digitalWrite(RELAY_PIN, led1State ? LOW : HIGH);
  } else {
    // ON  -> HIGH, OFF -> LOW
    digitalWrite(RELAY_PIN, led1State ? HIGH : LOW);
  }
}

void sendHtml() {
  String response = R"(
    <!DOCTYPE html><html>
      <head>
        <title>ESP32 Web Server Demo</title>
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <style>
          html { font-family: sans-serif; text-align: center; }
          body { display: inline-flex; flex-direction: column; }
          h1 { margin-bottom: 1.2em; } 
          h2 { margin: 0; }
          div { display: grid; grid-template-columns: 1fr 1fr; grid-template-rows: auto auto; grid-auto-flow: column; grid-gap: 1em; }
          .btn { background-color: #5B5; border: none; color: #fff; padding: 0.5em 1em;
                 font-size: 2em; text-decoration: none; border-radius:8px; display:inline-block; }
          .btn.OFF { background-color: #333; }
        </style>
      </head>
            
      <body>
        <h1>ESP32 Web Server</h1>

        <div>
          <h2>Relay (Buzzer)</h2>
          <a href="/toggle/1" class="btn RELAY_TEXT">RELAY_TEXT</a>
          <h2>LED 2</h2>
          <a href="/toggle/2" class="btn LED2_TEXT">LED2_TEXT</a>
        </div>
      </body>
    </html>
  )";
  // Replace placeholders with actual states
  response.replace("RELAY_TEXT", led1State ? "ON" : "OFF");
  response.replace("LED2_TEXT", led2State ? "ON" : "OFF");
  server.send(200, "text/html", response);
}

void setup(void) {
  Serial.begin(115200);

  // Initialize pins
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(LED2, OUTPUT);

  // Ensure relay is OFF at boot
  led1State = false;
  applyRelayOutput();
  digitalWrite(LED2, LOW);
  led2State = false;

  WiFi.begin(WIFI_SSID, WIFI_PASSWORD, WIFI_CHANNEL);
  Serial.print("Connecting to WiFi ");
  Serial.print(WIFI_SSID);
  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(100);
    Serial.print(".");
  }
  Serial.println(" Connected!");

  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  server.on("/", sendHtml);

  server.on(UriBraces("/toggle/{}"), []() {
    String which = server.pathArg(0);
    Serial.print("Toggle #");
    Serial.println(which);

    switch (which.toInt()) {
      case 1:
        // Toggle relay (using led1State variable)
        led1State = !led1State;
        applyRelayOutput();
        Serial.printf("Relay -> %s\n", led1State ? "ON" : "OFF");
        break;
      case 2:
        // Toggle LED2 (regular LED)
        led2State = !led2State;
        digitalWrite(LED2, led2State ? HIGH : LOW);
        Serial.printf("LED2 -> %s\n", led2State ? "ON" : "OFF");
        break;
      default:
        Serial.println("Unknown toggle");
        break;
    }

    sendHtml();
  });

  server.begin();
  Serial.println("HTTP server started");
}

void loop(void) {
  server.handleClient();
  delay(2);
}