MQTT in Arduino 2

You can use this library with different MQTT Brokers for ESP8266 or ESP32

Install

Sketch --> Include Library --> Manage Libraries --> search:"EspMQTT"

choos the "EspMQTTClient" by Patrick Lapointe

Example

<source lang="js" line start="2" highlight="4-6">

/*

 SimpleMQTTClient.ino
 The purpose of this exemple is to illustrate a simple handling of MQTT and Wifi connection.
 Once it connects successfully to a Wifi network and a MQTT broker, it subscribe to a topic and send a message to it.
 It will also send a message delayed 5 seconds later.

• /

1. include "EspMQTTClient.h"

EspMQTTClient client(

 "wifissid",           //WifiSSID
 "password", //WifiPassword
 "192.168.X.X.",  // MQTT Broker server ip
 "MQTTusername",     // MQTTUsername Can be omitted if not needed
 "MQTTpassword",     // MQTTPassword Can be omitted if not needed
 "Lolin",       // Client name that uniquely identify your device
 1883                // The MQTT port, default to 1883. this line can be omitted
 );

void setup() {

 Serial.begin(115200);

 // Optional functionalities of EspMQTTClient
 client.enableDebuggingMessages(); // Enable debugging messages sent to serial output
 client.enableHTTPWebUpdater(); // Enable the web updater. User and password default to values of MQTTUsername and MQTTPassword. These can be overridded with enableHTTPWebUpdater("user", "password").
 client.enableOTA(); // Enable OTA (Over The Air) updates. Password defaults to MQTTPassword. Port is the default OTA port. Can be overridden with enableOTA("password", port).
 client.enableLastWillMessage("TestClient/lastwill", "I am going offline");  // You can activate the retain flag by setting the third parameter to true

}

// This function is called once everything is connected (Wifi and MQTT) // WARNING : YOU MUST IMPLEMENT IT IF YOU USE EspMQTTClient void onConnectionEstablished() {

 // Subscribe to "mytopic/test" and display received message to Serial
 client.subscribe("mytopic/test", [](const String & payload) {
   Serial.println(payload);
 });

 // Subscribe to "mytopic/wildcardtest/#" and display received message to Serial
 client.subscribe("mytopic/wildcardtest/#", [](const String & topic, const String & payload) {
   Serial.println("(From wildcard) topic: " + topic + ", payload: " + payload);
 });

 // Publish a message to "mytopic/test"
 client.publish("mytopic/test", "This is a message"); // You can activate the retain flag by setting the third parameter to true

 // Execute delayed instructions
 client.executeDelayed(5 * 1000, []() {
   client.publish("mytopic/wildcardtest/test123", "This is a message sent 5 seconds later");
 });

}

void loop() {

 client.loop();

}

<\source>