MicroPython MQTT: A Non-blocking Way to Communicate with MQTT Broker

The MicroPython MQTT library is designed for developers using MicroPython, providing a non-blocking way to communicate with an MQTT Broker. This library supports various small devices, such as ESP8266, ESP32, and Pyboard D, allowing developers to easily handle message passing between devices and achieve data exchange through a publish/subscribe model.

Basics of MQTT Protocol

MQTT is a lightweight messaging protocol primarily used for communication between devices. It employs a publish/subscribe mechanism, allowing multiple clients to interact with a server (Broker). Clients can subscribe to specific topics and receive messages published by other clients. MQTT also offers three different Quality of Service (QoS) levels to meet the needs of various application scenarios.

Features and Advantages of the Library

The MicroPython MQTT library has several notable features:

• • Non-blocking Operation: The library is designed using non-blocking techniques, ensuring that message processing does not block the execution of the main program, allowing it to work seamlessly with other asynchronous operations.

• • Automatic Recovery Mechanism: When WiFi or the Broker encounters issues, the library can automatically recover the connection to the Broker, maintaining communication continuity.

• • Reliable Data Transmission: Fully supports QoS level 1, ensuring that messages are not lost during transmission. Additionally, the retransmission mechanism maintains data integrity even in unstable network conditions.

Supported Hardware Platforms

The MicroPython MQTT library supports various hardware platforms, including:

• • ESP8266

• • ESP32

• • Pyboard D

• • Arduino Nano RP2040 Connect

• • Raspberry Pi Pico W

Installation and Configuration

Installing the MicroPython MQTT library can be done in several ways, with the most common being through the command line tool mpremote to install the required library files. Users need to configure the mqtt_local.py file, which includes WiFi credentials and the address of the Broker, to connect correctly to the MQTT Broker.

For example:

from mqtt_as import config

config['server'] = '192.168.0.10'  # Change to the actual Broker address
config['ssid'] = 'your_network_name'
config['wifi_pw'] = 'your_password'

Simple Usage Example

Below is a basic usage example demonstrating how to connect and communicate with an MQTT Broker:

from mqtt_as import MQTTClient, config
import asyncio

async def main(client):
    await client.connect()
    await client.subscribe('foo_topic', 1)

    while True:
        await asyncio.sleep(5)
        print('Publishing message')
        await client.publish('result', 'Hello from MicroPython!', qos=1)

config['ssid'] = 'your_network_name'
config['wifi_pw'] = 'your_password'
client = MQTTClient(config)

try:
    asyncio.run(main(client))
finally:
    client.close()

By running this code, you can easily publish messages to the specified topic while subscribing to receive messages from other clients.

Conclusion

The MicroPython MQTT library provides a powerful and flexible way for communication between IoT devices. Its non-blocking architecture and automatic recovery features ensure efficient operation even in unstable network environments. Whether for simple data transmission or complex IoT application development, this library is an indispensable tool for developers.

Project URL: https://github.com/peterhinch/micropython-mqtt