WOKWI ESP32 connects to the free public MQTT broker

WOKWI ESP32 connects to the free public MQTT broker

WOKWI程式

#include <WiFi.h>

#include <PubSubClient.h>

// WiFi

const char *ssid = "Wokwi-GUEST"; // Enter your WiFi name

const char *password = "";  // Enter WiFi password

// MQTT Broker

const char *mqtt_broker = "broker.emqx.io";

const char *topic = "alex9ufo/esp32/test";

const char *mqtt_username = "emqx";

const char *mqtt_password = "public";

const int mqtt_port = 1883;

WiFiClient espClient;

PubSubClient client(espClient);

unsigned long previousMillis = 0;

unsigned long interval = 10000;

//===========================================================

void setup() {

 // Set software serial baud to 115200;

 Serial.begin(115200);

 // connecting to a WiFi network

 WiFi.begin(ssid, password);

 while (WiFi.status() != WL_CONNECTED) {

     delay(500);

     Serial.println("Connecting to WiFi..");

 }

 Serial.println("Connected to the WiFi network");

 //connecting to a mqtt broker

 client.setServer(mqtt_broker, mqtt_port);

 client.setCallback(callback);

 while (!client.connected()) {

     String client_id = "esp32-client-";

     client_id += String(WiFi.macAddress());

     Serial.printf("The client %s connects to the public mqtt broker\n", client_id.c_str());

     if (client.connect(client_id.c_str(), mqtt_username, mqtt_password)) {

         Serial.println("Public emqx mqtt broker connected");

     } else {

         Serial.print("failed with state ");

         Serial.print(client.state());

         delay(2000);

     }

 }

 // publish and subscribe

 client.publish(topic, "Hi EMQX I'm ESP32 ^^");

 client.subscribe(topic);

}

//===========================================================

void callback(char *topic, byte *payload, unsigned int length) {

 Serial.print("Message arrived in topic: ");

 Serial.println(topic);

 Serial.print("Message:");

 for (int i = 0; i < length; i++) {

     Serial.print((char) payload[i]);

 }

 Serial.println();

 Serial.println("-----------------------");

}

//===========================================================

void loop() {

 client.loop();

 unsigned long currentMillis = millis();

 if (currentMillis - previousMillis >=interval) {

    client.publish(topic, "Hi EMQX I'm ESP32 ^^");

    previousMillis = currentMillis;

 }

}

MQTT X client設定