#include <WiFi.h>
#include <PubSubClient.h>
const char* mqttHost = "broker.hivemq.com";
const int mqttPort = 1883;
const char* topic = "esp32/testme";
String clientId = "ESP32Client-" + String(random(0xffff), HEX);
void callback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message arrived [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}
Serial.println();
}
WiFiClient wifiClient;
PubSubClient mqttClient(mqttHost, mqttPort, callback, wifiClient);
void setup() {
Serial.begin(115200);
setup_wifi();
}
void setup_wifi() {
delay(10);
WiFi.begin("Wokwi-GUEST", "");
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
randomSeed(micros());
Serial.println("");
Serial.println("WiFi connected. IP address:");
Serial.println(WiFi.localIP());
}
void reconnect() {
// Loop until we're reconnected
while (!mqttClient.connected()) {
Serial.println("Client is not connected to MQTT broker. Calling client.connect()...");
// Attempt to connect
Serial.print("ClientId:");
Serial.println(clientId);
if (mqttClient.connect(clientId.c_str())) {
Serial.println("Client is connected to MQTT broker.");
// subscribe to something...
if (mqttClient.subscribe(topic)) {
Serial.println("SUBSCRIBE successful.");
} else {
Serial.println("SUBSCRIBE unsuccessful.");
}
// publish something...
if (mqttClient.publish(topic, "Hello, I am ready!")) {
Serial.println("PUBLISH successful.");
} else {
Serial.println("PUBLISH unsuccessful.");
}
} else {
Serial.print("Client.connect() has failed, Reason Code =");
Serial.print(mqttClient.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
void loop() {
if (!mqttClient.connected()) {
Serial.println("Client is not connected to MQTT broker. Calling reconnect()...");
reconnect();
}
mqttClient.loop();
}