ESP32 Gửi Dữ Liệu MQTT Qua Wi-Fi và Điều Khiển LED

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

// Định nghĩa chân LED (LOW là bật)
#define LED1 5
#define LED2 12
#define LED3 13

// WiFi Config
const char* WIFI_SSID = "iMTrongThan";
const char* WIFI_PASS = "imaker12345";

// MQTT Config
const char* MQTT_SERVER = "broker.hivemq.com";
const int   MQTT_PORT   = 1883;

// MQTT client sử dụng WiFi
WiFiClient wifiClient;
PubSubClient mqttClient(wifiClient);

// Xử lý tin nhắn MQTT nhận được
void mqttCallback(char* topic, byte* payload, unsigned int length) {
  String topicStr = String(topic);
  String message;

  for (unsigned int i = 0; i < length; i++) {
    message += (char)payload[i];
  }

  Serial.println("📩 Topic: " + topicStr);
  Serial.println("📄 Message: " + message);

  // Điều khiển LED dựa vào topic
  if (topicStr == "esp32/zenopcb/led1") {
    digitalWrite(LED1, message == "on" ? LOW : HIGH);
  } else if (topicStr == "esp32/zenopcb/led2") {
    digitalWrite(LED2, message == "on" ? LOW : HIGH);
  } else if (topicStr == "esp32/zenopcb/led3") {
    digitalWrite(LED3, message == "on" ? LOW : HIGH);
  }
}

// Kết nối lại MQTT nếu mất
void reconnectMQTT() {
  while (!mqttClient.connected()) {
    Serial.print("🔄 Kết nối MQTT...");
    String clientId = "ESP32Client-ZENOPCB";
    if (mqttClient.connect(clientId.c_str())) {
      Serial.println("✅ Thành công!");

      // Subscribe các topic điều khiển LED
      mqttClient.subscribe("esp32/zenopcb/led1");
      mqttClient.subscribe("esp32/zenopcb/led2");
      mqttClient.subscribe("esp32/zenopcb/led3");
    } else {
      Serial.print("❌ Thất bại, lỗi: ");
      Serial.println(mqttClient.state());
      delay(2000);
    }
  }
}

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

  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);

  // Nháy LED khi khởi động
  digitalWrite(LED1, LOW);
  digitalWrite(LED2, LOW);
  digitalWrite(LED3, LOW);
  delay(500);
  digitalWrite(LED1, HIGH);
  digitalWrite(LED2, HIGH);
  digitalWrite(LED3, HIGH);
  delay(500);
  digitalWrite(LED1, LOW);
  digitalWrite(LED2, LOW);
  digitalWrite(LED3, LOW);

  // Kết nối WiFi
  WiFi.begin(WIFI_SSID, WIFI_PASS);
  Serial.print("📡 Đang kết nối WiFi");
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print(".");
    delay(500);
  }
  Serial.print("\n✅ WiFi Connected. IP: ");
  Serial.println(WiFi.localIP());

  // Cấu hình MQTT
  mqttClient.setServer(MQTT_SERVER, MQTT_PORT);
  mqttClient.setCallback(mqttCallback);
}

void loop() {
  if (!mqttClient.connected()) {
    reconnectMQTT();
  }

  static unsigned long lastSend = 0;
  if (millis() - lastSend > 3000) {
    String message = "Hello from ESP32 WiFi -> " + String(random(100, 900));
    mqttClient.publish("esp32/zenopcb", message.c_str());
    Serial.println("📤 Đã gửi: " + message);
    lastSend = millis();
  }

  mqttClient.loop();
}