Home Sweet Home

Automating your four walls does not necessarily require commercial solutions. With a little skill, you can develop your own projects on a low budget.

-  Gerhard Schauer

Home automation offers many opportunities, but equally harbors many risks. If you succeed in becoming independent of commercial products, you can save money while retaining control over what data flows where. In this case, the Message Queuing Telemetry Transport (MQTT) protocol proves to be very useful.

A previous article on Z-Wave [1] showed how you can bring the Raspberry Pi up to speed with Home Assistant and components available on the market to attain the goal of achieving automation magic in your home without human interference. Plenty of components can be addressed by Home Assistant, even without the cloud. The only limits are your wallet and your imagination.

This sequel explains how you tweak both the price and the DIY factors of the components. The Raspberry Pi from model 3 onward comes with a wireless interface that is also available in many microcontroller modules and is likely to open many doors. The glue that connects the whole thing to the Home Assistant environment looked at in the previous article is an IP-capable protocol that saw the light of day long before any Internet of Things (IoT) hype did: MQTT.

The MQTT protocol was introduced in 1999 and is a text-based protocol that runs over TCP on any IP network. Transport Layer Security (TLS) can optionally be used for encryption. The sensors and actuators communicate as clients with the broker, which acts as the communications hub. Addressing relies on what are known as "topics." Transmitters are referred to as publishers, and receivers as subscribers.

Testing MQTT

To implement the protocol on the Raspberry Pi, you first need the mosquitto package. For the small implementation tests that follow, you will also need the matching client. You can set up both components on the Raspberry Pi with the commands:

$ sudo apt-get install mosquitto

$ apt-get mosquitto-clients