LedControl MQTT - ESP32 - TKS

#include <WiFi.h>
#include <PubSubClient.h>

const char* ssid = "Wokwi-GUEST";
const char* password = "";

const char* mqtt_server = "test.mosquitto.org";
const char* mqtt_topic  = "tks/led/control";

const int LED_PIN = 32;

WiFiClient espClient;
PubSubClient client(espClient);

void callback(char* topic, byte* payload, unsigned int length) {
  String msg;
  for (unsigned int i = 0; i < length; i++) {
    msg += (char)payload[i];
  }
  msg.trim();

  if (msg == "on") {
    digitalWrite(LED_PIN, HIGH);
  }
  else if (msg == "off") {
    digitalWrite(LED_PIN, LOW);
  }
}

void setup() {
  pinMode(LED_PIN, OUTPUT);
  digitalWrite(LED_PIN, LOW);

  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(200);
  }

  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);

  //УНИКАЛНО MQTT CLIENT ID
  String clientId = "wokwi-led-" + WiFi.macAddress();

  while (!client.connected()) {
    client.connect(clientId.c_str());
    delay(500);
  }

  client.subscribe(mqtt_topic);
}

void loop() {
  client.loop();
}