esp32 mqtt.ino

#include <WiFiManager.h>  // https://github.com/tzapu/WiFiManager
#include <PubSubClient.h> // https://github.com/knolleary/pubsubclient/

#define BUILTIN_LED 2
#define CONNECTION_TOPIC "/F-litter/connection/status"
#define MQTT_RECONNECTIO_MS_TIME 5000

WiFiClient espClient;
PubSubClient mqttClient(espClient);

long lastReconnectAttempt = 0;
const char * mqttServer = "broker.mqttdashboard.com";
String clientId = "F-litterCat-";

void callback(char *topic, byte *payload, unsigned int payloadLenght)
{
  Serial.println("recibiendo informacion desde el topico:");
  Serial.println(topic);
}

boolean reconnectMqtt()
{
  
  clientId += String(random(0xffff), HEX);
  // Attempt to connect
  if (mqttClient.connect(clientId.c_str(), CONNECTION_TOPIC, 2, false, "0"))
  {

    // Once connected, publish an announcement...
    mqttClient.publish(CONNECTION_TOPIC, "1");
    // ... and resubscribe
    mqttClient.subscribe("inTopic");
  }
  return mqttClient.connected();
}

void setup()
{
  // put your setup code here, to run once:
  WiFi.mode(WIFI_STA); // explicitly set mode, esp defaults to STA+AP
  // define the pin on board as output
  pinMode(BUILTIN_LED, OUTPUT);

  Serial.begin(115200);

  //WiFiManager, Local intialization. Once its business is done, there is no need to keep it around
  WiFiManager wm;

  // Automatically connect using saved credentials,
  // if connection fails, it starts an access point with the specified name ( "AutoConnectAP"),
  // if empty will auto generate SSID, if password is blank it will be anonymous AP (wm.autoConnect())
  // then goes into a blocking loop awaiting configuration and will return success result

  bool res;
  res = wm.autoConnect("F-litterCat AP", "IOT12345"); // password protected ap

  if (!res)
  {
    Serial.println("Failed to connect");
    // ESP.restart();
    while (1)
    {
      digitalWrite(BUILTIN_LED, HIGH);
      delay(100);
      digitalWrite(BUILTIN_LED, LOW);
      delay(100);
    }
  }
  else
  {
    //if you get here you have connected to the WiFi
    Serial.println("connected...yeey :)");
  }

  mqttClient.setServer(mqttServer, 1883);
  mqttClient.setCallback(callback);
}

void loop()
{
  // put your main code here, to run repeatedly:
  if (!mqttClient.connected())
  {
    long now = millis();
    if (now - lastReconnectAttempt > MQTT_RECONNECTIO_MS_TIME)
    {
      lastReconnectAttempt = now;
      // Attempt to reconnect
      if (reconnectMqtt())
      {
        lastReconnectAttempt = 0;
      }
    }
  }
  else
  {
    // Client connected

    mqttClient.loop();
  }

}