Temperature Sensor – Mk II

My first go at creating a simple battery powered temperature sensor was really interesting and fun to do, but, like any project, there are always way to make it better!

For my Mark II sensor, there were a few things I wanted to improve:

Mesh Networking

I’m interesting in exploring the concept of mesh networking. Within the Expressif family of devices, there are two flavors that I’m aware of; WiFi mesh and Bluetooth Low Energy Mesh. The ESP32 platform supports both of these. My current Temperature Sensor is built upon the ESP8266, but moving to the ESP32 should be straight forward.

In Progress – .

More Data

Mk I of my sensor was a simple temperature probe. I wanted to expand on this after I found the Bosch BME280 sensor. This little sensor can capture temperature, pressure and humidity. The boards I ordered work on the I2C protocol, so I’ll have to figure that out.

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MQTT Discovery

I use the Hass.io platform to manage my automation at home. It supports a simple MQTT interface for receiving data and sending commands. Typically, you would configure the devices within a config file, but it does support a discovery protocol, which allows devices to make themselves known to Hass and to provide all the information required for Hass to use them.

I would like my temperature sensors to support this mode, so that when they fire themselves up for the first time, they would register themselves automatically.

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Battery Life

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I’d like to enclose my sensor in a nice case, so that I can mount them on the wall in way that doesn’t look completely ugly!

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Low battery notifications

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My home network needs an upgrade!

After a long wait, I finally got a decent broadband connection and I’m thrilled. Unfortunately, this isn’t the end of the story!

Plusnet are now providing me with a 40MB FTTC based broadband connection and I get a reported connection speed of 38MB when I use www.speedtest.net. An awesome speed really. But there is one issue. I only get this speed when I’m connected to the router via an ethernet cable. As soon as I connect my Macbook Pro to the router’s WiFi, I get a reported 20MB connection, just over half the speed I’m expecting.

And it gets worse. In my apartment, my PC is in a spare bedroom, about as far from the router as possible. WiFi can’t stretch that far, so I’ve been using a Netgear Powerline setup (with a 200MB max connection speed). When I run the speedtest from my PC, I get a miserable 4MB reported connection speed ;( The tools to run tests on my Powerline configuration won’t install on my PC, so I’m unable to see what sort of connection speed I’m getting across the electicity based connection.

Since this lousy speed needs to be addressed, I’ve put my Apple Airport Express in the main room, which offers a 802.11N connection and my laptop is now reporting a satisfying 30-32 MB connection. I’ve also ordered a Devolo Powerline kit and I hope that four years of advancements (I bought my Netgear kit in 2007) will ensure a better connection between the two rooms. If it doesn’t, I’ll have to think about using WiFi extenders or running a very long ethernet cable between the two rooms.

The kit is due to arrive from Amazon tomorrow, so I’ll update this post with the results!


After installing my brand new Devolo dLAN 200 wireless Homeplug kit and I’m pleased to report I’m seeing much improved speeds across the electricity network in my apartment.

The wireless network in the second bedroom is now reporting a 30MB connection, whilst the PC is getting just over 34! This is about what I’d was hoping for so I’m very pleased. In the four years since I purchased the Netgear kit, there have been some impressive performance gains!

The Devolo kit does come with a build-in 802.11N router, so I’ll give that a try in the living room and see what happens. I might even try “extending” the WiFi network.

Another Update

Seems that the WiFi network created by the Devolo plug cannot be extended. At least that is what my Apple Airport Express is saying. I’m not going to spend any time investigating this so I guess I’ll have to solve that another day.