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Build Connected IoT Devices with Arduino and MQTT Telemetry Transport (MQTT)

Percy Bysshe Shelley

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Published in Hands On Internet Of Things With MQTT: Build Connected IoT Devices With Arduino And MQ Telemetry Transport (MQTT)

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<meta name="keywords" content="Arduino, IoT, MQTT, Telemetry, Connected devices, Electronics, Programming"> The Internet of Things (IoT) is rapidly changing the way we live and work. IoT devices are being used in a wide variety of applications, from home automation to industrial monitoring. In order to communicate with each other, IoT devices need a common language. MQTT is a lightweight messaging protocol that is specifically designed for IoT applications. In this tutorial, we will show you how to build connected IoT devices using Arduino and MQTT. We will cover everything from setting up your Arduino board to understanding MQTT topics and subscriptions. By the end of this tutorial, you will be able to build your own IoT devices that can communicate with each other and with the cloud. <h2>What is MQTT?</h2> MQTT is a lightweight messaging protocol that is specifically designed for IoT applications. It is a publish/subscribe protocol, which means that devices can publish messages to a topic and other devices can subscribe to that topic to receive the messages. MQTT is a very efficient protocol, and it can be used to send small amounts of data over low-bandwidth networks. MQTT is a popular choice for IoT applications because it is: * **Lightweight:** MQTT is a very lightweight protocol, which makes it ideal for use on resource-constrained devices. * **Efficient:** MQTT is a very efficient protocol, and it can be used to send small amounts of data over low-bandwidth networks. * **Reliable:** MQTT is a reliable protocol, and it can be used to ensure that messages are delivered even in the event of network disruptions. <h2>Setting Up Your Arduino Board</h2> In order to build connected IoT devices with Arduino, you will need to set up your Arduino board. To do this, you will need the following: * An Arduino board * A USB cable * An MQTT broker Once you have gathered your materials, you can follow these steps to set up your Arduino board: 1. Connect your Arduino board to your computer using the USB cable. 2. Open the Arduino IDE. 3. Select the correct board type and port from the Tools menu. 4. Copy the following code into the Arduino IDE: cpp #include <mqtt.h> MQTTClient client; void setup(){client.begin("127.0.0.1", 1883); client.publish("test", "Hello, world!"); }void loop(){client.loop(); }5. Click the "Upload" button to upload the code to your Arduino board. 6. Open the Serial Monitor in the Arduino IDE. 7. You should see a message that says "Hello, world!" printed in the Serial Monitor. <h2>Understanding MQTT Topics and Subscriptions</h2> MQTT topics are used to organize messages. A topic can be thought of as a channel or a category. Devices can publish messages to a topic, and other devices can subscribe to that topic to receive the messages. MQTT subscriptions are used to specify which topics a device wants to receive messages from. A device can subscribe to multiple topics. To subscribe to a topic, you need to use the `subscribe()` function. The `subscribe()` function takes two parameters: * The topic that you want to subscribe to * The quality of service (QoS) that you want to use The QoS parameter specifies how important it is to receive the message. There are three QoS levels: * **QoS 0:** This is the lowest QoS level. Messages are not guaranteed to be delivered, and they may be lost if the network is congested. * **QoS 1:** This is the middle QoS level. Messages are guaranteed to be delivered at least once, but they may be duplicated if the network is congested. * **QoS 2:** This is the highest QoS level. Messages are guaranteed to be delivered exactly once, even if the network is congested. To publish a message to a topic, you need to use the `publish()` function. The `publish()` function takes three parameters: * The topic that you want to publish to * The payload of the message * The QoS level that you want to use <h2>Building Your Own IoT Devices</h2> Now that you understand the basics of MQTT, you can start building your own IoT devices. Here are a few ideas to get you started: * **Temperature sensor:** A temperature sensor can be used to monitor the temperature of a room or a piece of equipment. The sensor can publish the temperature data to an MQTT topic, and you can use a dashboard or a mobile app to visualize the data. * **Motion sensor:** A motion sensor can be used to detect motion in a room or a building. The sensor can publish the motion data to an MQTT topic, and you can use a dashboard or a mobile app to receive alerts when motion is detected. * **Light sensor:** A light sensor can be used to measure the amount of light in a room or a building. The sensor can publish the light data to an MQTT topic, and you can use a dashboard or a mobile app to visualize the data. These are just a few examples of the many different types of IoT devices that you can build. With a little creativity, you can use Arduino and MQTT to build any type of IoT device that you can imagine. MQTT is a powerful tool that can be used to build connected IoT devices. In this tutorial, we have shown you how to set up your Arduino board, understand MQTT topics and subscriptions, and build your own IoT devices. We encourage you to experiment with MQTT and build your own IoT projects.

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