Implementasi MQTT dalam Arduino

Summary

The lesson demonstrates how to connect an Arduino-compatible ESP8266 or ESP32 board to MQTT and use messages to control hardware.

MQTT Basics

The instructor reviews the publisher–subscriber model: publishers send messages to topics, subscribers receive messages from topics, and an MQTT broker routes messages. MQTT Explorer is used to inspect and publish messages.

Arduino Setup

In the Arduino IDE, select the board and port, then install a compatible MQTT library through Library Manager. The lesson checks the library examples and board compatibility, noting that ESP8266 and ESP32 boards may require different examples or settings.

Wi-Fi and Broker Configuration

The ESP board connects over Wi-Fi, using a hotspot in the demonstration. The sketch’s Wi-Fi credentials, broker address, and topic names must match the MQTT Explorer settings. A public Mosquitto test broker is used. The instructor recommends choosing a distinctive topic to avoid collisions with other users.

Testing Messages

The board publishes a test message that appears in MQTT Explorer. Messages can also be sent from MQTT Explorer to the board. The Serial Monitor helps check connection progress and incoming or outgoing messages. Connection failures and Wi-Fi scanning issues are discussed as common troubleshooting problems.

Controlling LEDs

An example callback checks the received message payload and switches an LED based on its contents. Because the built-in LED’s logic may be inverted, the instructor recommends testing whether HIGH or LOW turns it on. The demonstration also adapts the code to control an external LED connected to a selected output pin.

Exercise

Extend the sketch to control four lights using a message such as 1100 or 1001. Students are encouraged to parse the message so that each character determines the state of one light.

Project Reviews and Assessment

The latter part of the class reviews student IoT project ideas, including hydroponics, water-level monitoring, poultry-house automation, and safety monitoring. The instructor recommends checking whether similar products already exist, finding a credible reference or real-world example, and adding a useful feature rather than simply copying an existing product.

Students are also advised to improve the presentation of their prototypes and submit a video of their work. The upcoming assessment will cover IoT theory and students’ projects.

Main Speakers and Sources

• Main speaker: The instructor leading the Arduino/MQTT lesson and project reviews.
• Other voices: Students asking questions and discussing their projects.
• Tools and examples: Arduino IDE, MQTT Explorer, an ESP8266/ESP32 board, and a public Mosquitto test broker.