Simulasi Telemetri ESP32 & MQTT HiveMQ di Browser (Tanpa Alat Fisik)

1. Tujuan Praktikum

Menyelesaikan praktikum Internet of Things (IoT) protokol Machine-to-Machine (M2M) menggunakan MQTT (Message Queuing Telemetry Transport) tanpa kendala hardware rusak, kekurangan kabel jumper, atau ketiadaan router WiFi fisik.

2. Prasyarat & Lingkungan

Akses browser ke simulator online gratis: Wokwi.com.
Broker MQTT Publik: broker.hivemq.com (Port TCP: 1883).
MQTT Client Dashboard: MQTTX Desktop Client atau web client di http://www.hivemq.com/demos/websocket-client/.

3. Rangkaian Virtual di Wokwi

Buka Wokwi, buat proyek baru: ESP32 Arduino.
Tambahkan komponen sensor suhu dan kelembaban DHT22.
Hubungkan pin:
- VCC DHT22 -> 3V3 ESP32
- GND DHT22 -> GND ESP32
- SDA DHT22 -> GPIO 15 ESP32

4. Kode Lengkap Arduino / C++

CPP

#include <WiFi.h>
#include <PubSubClient.h>
#include <DHTesp.h>

const int DHT_PIN = 15;
DHTesp dhtSensor;

// Konfigurasi WiFi Wokwi Virtual
const char* ssid = "Wokwi-GUEST";
const char* password = "";

// Konfigurasi MQTT Broker Publik
const char* mqtt_server = "broker.hivemq.com";
const int mqtt_port = 1883;
const char* mqtt_topic = "boash/trm/telemetry/suhu";

WiFiClient espClient;
PubSubClient client(espClient);

void setup_wifi() {
  delay(10);
  Serial.println("Menghubungkan ke Virtual WiFi...");
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nWiFi Terkoneksi!");
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Mencoba koneksi MQTT...");
    String clientId = "ESP32Boash-" + String(random(0xffff), HEX);
    if (client.connect(clientId.c_str())) {
      Serial.println("Terhubung ke HiveMQ Broker!");
    } else {
      delay(5000);
    }
  }
}

void setup() {
  Serial.begin(115200);
  dhtSensor.setup(DHT_PIN, DHTesp::DHT22);
  setup_wifi();
  client.setServer(mqtt_server, mqtt_port);
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  TempAndHumidity data = dhtSensor.getTempAndHumidity();
  String payload = "{\"suhu\":" + String(data.temperature, 2) + 
                   ",\"lembab\":" + String(data.humidity, 1) + "}";
                   
  client.publish(mqtt_topic, payload.c_str());
  Serial.println("Publikasi data: " + payload);
  delay(3000);
}

5. Pengujian & Monitoring

Klik tombol Play (Simulate) di Wokwi.
Buka web dashboard HiveMQ WebSocket Client di tab browser baru.
Hubungkan ke broker.hivemq.com port 8000 (atau 8884 SSL).
Klik Subscribe to topic, masukkan topik: boash/trm/telemetry/suhu.
Klik sensor DHT22 di simulator Wokwi untuk mengubah suhu. Anda akan melihat payload JSON diterima secara instan tanpa jeda!

6. Referensi

Oasis Standard: MQTT Version 5.0 Specification.
Wokwi Documentation: ESP32 WiFi Simulation.