Category: Smart Home

Automating your home with openHAB

In the past few weeks, I’ve been actively looking at how I can manage all my ‘smart’ (or ZigBee/WiFi connected) IoT devices in my home from a central place.

I started with Home Assistant, but quickly found the user interface a bit too clunky for my appetite. Searching around, openHAB came up as a good contender and it meets almost all of my wants – active development, an APT repository, the ability to run under Docker and well-used by many people.

Data structure

The thinking behind openHAB’s data structure confused me at first – a combination of things, channels and items didn’t seem logical to me until I got stuck in. It turns out it’s quite clever:

  • A thing is a physical device, such as a smart plug or bulb
  • Each thing has one or more channels, which are individually accessible data points on the device, such as an on/off switch (input), or energy usage monitor (output)
  • Links connect a channel to an item, such as energy usage to a metric (output) or on/off toggle (input). Channels can have multiple links too

Where a thing is accessed via another device, such as a Hue bulb, a special type of thing called a bridge needs to be defined. The bridge discovers other things connected to it and publishes them ready for configuration. Bridges are instances of a binding, so if you have three Hue controllers, you have three bridges defined.

Lighting things up

Connecting my Hue lights was trivial. The Hue binding is included in the openHAB distribution, and is installed by clicking ‘Install’. Adding the bridge requires the IP address of the Hue bridge and a username, and a quick press of the hardware button on the bridge to pair things together. At this point, the bridge reports the devices connected to it, and it’s just a case of adding them as things.

Conclusion

Despite the UI feeling a bit fiddly to edit – similar to writing HTML in Notepad but having to indent it as it’s YAML – I absolutely love openHAB. In the coming weeks, I’ll write up how I connected my Glow IHD and CAB, a Tasmota switch for my porch light, my Ring doorbell and the problems I had with my TP-Link Tapo devices and how easy it was to fix them.

Monitoring your appliances’ power

I recently posted about real-time data from your smart meter and all was good, but then thread by Robin Hawkes on Twitter caught my eye:

These devices connect to your WiFi network and allow you to switch a connected device on or off, on a schedule if you require, and also monitor power consumption. That last bit is the most important for me – knowing how much energy I’m consuming.

After researching Tasmota, an open firmware for simple home automation devices, and checking a bunch of reviews on the TP-Link Tapo P110‘s firmware, it looked like these P110s would do just what I needed – simple power monitoring for not much of an initial outlay.

LocalBytes were out of stock of both of these items when I looked, so I took the plunge and ordered one from elsewhere. Well, I ordered eight because I was feeling quite bold.

Initial setup

Trivial. Download the Android (or iOS presumably) app, plug in a device, find its wireless network and configure it to connect to your wireless network. It reboots and that’s about it.

Firmware updates can be scheduled automatically, but I don’t know whether this will switch the power off to any connected device or not. Something to check later.

Control and monitoring

The mobile app makes it quite easy to switch a device on and off, to set a schedule, and to see power consumption. But it’s a mobile app, and I want the data somewhere I can analyse it easily.

Home Assistant to the rescue! Running HA under Docker is really easy if you know Docker. I could have re-purposed one of my Raspberry Pi as I can’t get a new OpenVMS Community licence for VAX any more, but I wanted to try HA quickly to see if it fitted my needs.

Support for the P110 devices doesn’t come as standard, but there’s a community-written workaround for that. A little fiddly and not really what I’d expect, but it works.

Next steps

Oh boy, there’s a lot I want to do.

First off, I want to push the sensor data out from these devices in to an MQTT server such as Mosquitto and have Telegraf pull this data in to a time-series database so I can visualise it with Grafana.

Other things I want to do include automatically checking my Google Calendar and setting the heating to come up early when I’m doing a morning clinic, or having it come on a bit later when I’m at home that day. I want to get an inline power switch for my porch light and turn that on between dusk and sometime around midnight.

Real-time Smart Meter data

A year or two ago, I took the plunge and had a smart meter installed. I naively thought that being able to read energy usage was a simple case of connecting a ConBee-II or similar to the ZigBee HAN.

To save anyone else from going through the same range of emotions as I did, here’s how you can read your own smart meter data.

Technology primer

Your electricity meter has two parts – a metering device, and a communications device located at the top. The electricity meter periodically sends energy usage information over a communications network to your supplier. It’s easy when you have a continual supply of electricity.

If you have a gas meter, it doesn’t have its own communications device. To do so would require a power supply to the gas meter – readily available on an electricity meter. Instead, the gas meter sends energy usage to the electricity meter every 30 minutes and therefore only has a long-life battery installed.

Getting access to the data

There are two ways to get access to real-time electricity and real-ish time gas usage data. Neither of them involve pairing your own device.

The best option is to buy a combined In-Home Display (IHD) and Customer Access Device (CAD) from Glow (Hildebrand Technology) sell a combined in-home display (IHD) and Customer Access Device (CAD) for around £65. This arrives already paired with your smart meter, and you connect it to your home wireless network, and it sends out data from your smart meter to an MQTT server (which can be on your local network too), ready for you to consume yourself. The device needs Internet access for firmware updates, but your data is kept locally.

The other option is to use intermediary such as Glowmarkt, who are a DCC Other User and can request your metering data from the Data Communications Company, then make it available to you. This is a straightforward process, although you need to go through an industry-mandated security process to prove you are requesting access to your data and not somebody else’s. They make your data available via their MQTT server, although it’s not at the same level of granularity as having your own IHD/CAD.

The data

You can use the CAD as a simple IHD – it’s a lot prettier than the one supplied by my energy supplier (which I can still use). Electricity usage arrives every few seconds, with gas usage as and when the metering equipment makes it available.

The real power comes when you work with data in real-time, or at least as close to real-time as it’ll give you. Want to work out how much the tumble dryer cost to run? Or find out whether you’re OK with having your home a little cooler to save a bunch of energy?

Data format

The MQTT messages you receive are in JSON format, and contain data for three ‘clusters’ – Metering (0x0702), Prepayment (0x0705) and Device Management (0x0708). Each of these clusters has an attribute set – the Metering cluster presents the Reading Information Set (0x00), Formatting (0x03) and Historical Consumption (0x04). Finally, each attribute set has a set of key/value pairs. From this, you can decode that cluster 0x0708 (Device Management), attribute set 0x01 (Supplier Control Attribute Set) value 0x01 is the provider name.

Since the data is sent in JSON format, it’s quite easy to parse. If you want to dive straight in to the detail about what clusters and attribute sets are, the ZigBee Smart Energy Standard is available, although at 628 pages, it’s a heavy read.

Problems

The entire process was quick – the CAD arrived within a day or two of placing my order and was ready to use the moment I plugged it in. Getting my data in real-time took a little longer – it’s a manual process for the staff at Glow, but once it’s set up, that’s it.

The only problem is that there’s no formal support. For the first six months, the CAD disconnected itself from my WiFi network for no reason. Despite posting about my issue, there’s was no progress on it – but out of the blue, a firmware update arrived which fixed the issue.

Is the lack of formal support a problem? Likely not – unless you’re having an issue. Since the firmware update, I’ve had no problems with the IHD, other than a lack of time to play with and analyse the data.

Recommendation: go buy one!