esp32.ino

#include <WiFi.h>
extern "C" {
  #include "freertos/FreeRTOS.h"
  #include "freertos/timers.h"
}
#include <AsyncMqttClient.h>
#define LED_BUILTIN 2

#define WIFI_SSID "Error-404"
#define WIFI_PASSWORD "123452345"

#define MQTT_HOST IPAddress(192, 168, 1, 20) //MQTT BROKER IP ADDRESS

#define MQTT_PORT 1883
#define BROKER_USER "deepak"
#define BROKER_PASS "Letsfly1!"

AsyncMqttClient mqttClient;
TimerHandle_t mqttReconnectTimer;
TimerHandle_t wifiReconnectTimer;

unsigned long previousMillis = 0;   // Stores last time a message was published
const long interval = 10000;        // Interval at which to publish values

void connectToWifi() {
  Serial.println("Connecting to Wi-Fi...");
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
}

void connectToMqtt() {
  Serial.println("Connecting to MQTT...");
  mqttClient.connect();
}

void WiFiEvent(WiFiEvent_t event) {
  Serial.printf("[WiFi-event] event: %d\n", event);
  switch(event) {
    case SYSTEM_EVENT_STA_GOT_IP:
      Serial.println("WiFi connected");
      Serial.println("IP address: ");
      Serial.println(WiFi.localIP());
      connectToMqtt();
      break;
    case SYSTEM_EVENT_STA_DISCONNECTED:
      Serial.println("WiFi lost connection");
      xTimerStop(mqttReconnectTimer, 0); // ensure we don't reconnect to MQTT while reconnecting to Wi-Fi
      xTimerStart(wifiReconnectTimer, 0);
      break;
  }
}

void onMqttConnect(bool sessionPresent) {
  Serial.println("Connected to MQTT.");
  Serial.print("Session present: ");
  Serial.println(sessionPresent);
  
  // Subscribe to topic "led" when it connects to the broker
  uint16_t packetIdSub = mqttClient.subscribe("led", 0);
  Serial.print("Subscribing at QoS 2, packetId: ");
  Serial.println(packetIdSub);
  
  
}

void onMqttDisconnect(AsyncMqttClientDisconnectReason reason) {
  Serial.println("Disconnected from MQTT.");

  if (WiFi.isConnected()) {
    xTimerStart(mqttReconnectTimer, 0);
  }
}

void onMqttSubscribe(uint16_t packetId, uint8_t qos) {
  Serial.println("Subscribe acknowledged.");
  Serial.print("  packetId: ");
  Serial.println(packetId);
  Serial.print("  qos: ");
  Serial.println(qos);
}

void onMqttUnsubscribe(uint16_t packetId) {
  Serial.println("Unsubscribe acknowledged.");
  Serial.print("  packetId: ");
  Serial.println(packetId);
}

void onMqttMessage(char* topic, char* payload, AsyncMqttClientMessageProperties properties, size_t len, size_t index, size_t total) {
  
  String receivedMessage;
  for (int i = 0; i < len; i++) {
    Serial.println((char)payload[i]);
    receivedMessage += (char)payload[i];
  }
  // Turn the LED on or off accordingly to the message content
  if (strcmp(topic, "led") == 0) {
    if (receivedMessage == "true"){
      digitalWrite(LED_BUILTIN, HIGH);
    }
    if (receivedMessage == "false"){
      digitalWrite(LED_BUILTIN, LOW);
    }
  }
 
}



void setup() {
  Serial.begin(115200);
  Serial.println();
  Serial.println();
  pinMode (LED_BUILTIN, OUTPUT);
  digitalWrite(LED_BUILTIN, LOW);

  mqttReconnectTimer = xTimerCreate("mqttTimer", pdMS_TO_TICKS(2000), pdFALSE, (void*)0, reinterpret_cast<TimerCallbackFunction_t>(connectToMqtt));
  wifiReconnectTimer = xTimerCreate("wifiTimer", pdMS_TO_TICKS(2000), pdFALSE, (void*)0, reinterpret_cast<TimerCallbackFunction_t>(connectToWifi));

  WiFi.onEvent(WiFiEvent);

  mqttClient.onConnect(onMqttConnect);
  mqttClient.onDisconnect(onMqttDisconnect);
  mqttClient.onSubscribe(onMqttSubscribe);
  mqttClient.onUnsubscribe(onMqttUnsubscribe);
  mqttClient.onMessage(onMqttMessage);

  mqttClient.setServer(MQTT_HOST, MQTT_PORT);
  mqttClient.setCredentials(BROKER_USER, BROKER_PASS);

  connectToWifi();
}

void loop() {


}