This fall my Measure Your City sensor hub fell out of a tree during a storm. It seemed to be damaged, so I put it aside until I could think how or when to reinstate it. Later on I noticed from the log files that it seemed to have stopped working before it fell from the tree but I did not think it important. A few weeks ago I handed the sensor hub in with the team of Measure Your City that does repairs. It turns out the sensor hub was fully functional except for …. the batteries.

The problem was the firmware using too much battery power. Which is problematic given the stated aim of these LoRa sensors, to work on low power for a long time.
With a firmware upgrade and fresh batteries, the sensor hub is now back in action. The past day I’ve used it to measure the relative humidity in various rooms around the house as we suspected it might be too dry (it was, around 30-35% humidity). As there are 2 similar sensor hubs nearby, we are not without info on current outside conditions. I’ll reinstate the sensor hub outside again this weekend.

Meanwhile my own sensor hub as well as the two others a street away, use my recently installed The Things Network gateway to transport the data to the Measure Your City back-end. The gateway also sees several other sensors sending data through the gateway, although I don’t know what type of sensors those are.

Screenshot of the data passing through the gateway. The device in the first line is my own sensor hub.

After receiving the hardware for The Things Network, I now activated the gateway. I had first planned to run up a Cat6 to the top floor but I couldn’t successfully get the cable through the empty conduit that was available for that. Deciding not to wait until I get a cable through the conduit, I connected the Gateway to an ethernet port on the Netgear Orbi satellite that is installed on the top floor. This means it has a steady internet connection, even if not directly wired to the router yet.

The first few messages were sent, so now that ‘hello world’ is behind me, I am curious to see if there will be any traffic my gateway sees passing by.

A little over 2 years ago I backed a Kickstarter project The Things Network. It’s an order of magnitude cheaper version of a gateway for a LoRa (long range) network, for internet of things sensors etc. The fascinating thing about this The Things Network gateway is that it provides an infrastructure for very little money. With just 2 or 3 of these your entire city becomes your sandbox for IoT experiments. Usually it’s the other way around: you have cheap prototypes but to scale you need expensive infrastructure (a prototype car is fun, but also having to roll out a road system isn’t.) Now you are just as easy rolling out the infrastructure, as well as your prototypes.

It took a long time to arrive. The original team I think learned the hard way that setting up production and supply chains for hardware from scratch has a quite different dynamic compared to software development. This is not a new lesson for Kickstarter projects either. So the hardware which should have been delivered in June 2016 took until January 2018, some 18 months of delay. But now it’s here.

In the mean time I’ve co-initiated an IoT community in Enschede (community site here), before moving house to Amersfoort where another group is active. Here in Amersfoort I participated in the Measure Your City project, by placing a IoT sensor hub in my garden. With the hardware now arrived, I can’t wait to start experimenting. My gateway will come on-line as soon as I have run up a Cat 6 cable to our attic space, and can then help support the Measure Your City network, and any other projects that might take place in the vicinity.


The Things Network goodies arriving today: a gateway (shown), 4 uno’s (sensor platforms) and 2 nodes (prototyping platforms)

I’ve backed the Kickstarter project Point. Point is a device that on the front-end, in your home, works as a sensor hub and alarm. At the back-end it feeds a machine learning database that learns your patterns, and shows them to you over time. The whole set-up can be controlled by an app (both iPhone and Android). An API is provided, and it can also talk to IFTTT so you can connect your own triggers and devices if you want (and I do).

Point is an existing product, and this Kickstarter is meant to collect pre-orders for the second generation device.

To me the alarm part of the Point devices is less interesting than having a very capable sensorhub in the home. I’ve pre-ordered 4 Points, one for each floor of our home, and one for the garden shed. The sensors it has on board are:

  • Sound
  • Temperature
  • Humidity
  • Tamper
  • Barometric pressure
  • Ambient light
  • Motion/PIR

The company behind Point is Minut based in Sweden and China, and they state they take privacy protection seriously. It delivers on this, the company says, by doing a lot of the sensor signal processing locally in the device, and then only forwarding exceptions or events of interest (sudden sound e.g. in dB, though not the sound itself) to the centralised database at Minut. Traffic is encrypted, though the owner of the device has no posession of the keys. So in the event that the company should close up shop, there is the risk of having 4 smart but bricked devices, because there would be no way to read out the data it is sending, nor redirect the data to another database for instance. Given they’ve been around since 2014, this is their second run (and they know all about production and supply chains already) and that Thomas is now an investor and advisor to them, is reassuring. Hopefully over time they realise that true privacy also means I should have full control over how and where the traffic gets send, even if it means foregoing their entire back-end service. By the time the devices get delivered (May, so likely just in time for the Stuff That Matters 2018 Smart Homes unconference), I intend to open a discussion with them on those ‘privacy by design‘ aspects.

Now that we moved from Enschede to Amersfoort two weeks ago, we are starting to participate in local activities. Today I joined a workshop to build a sensor-hut for the ‘Measure your city‘ project. Initiated by amongst others ‘De War‘, also the people who started FabLab Amersfoort, it is a project to crowdsource measurements to track climate and climate changes inside the city.

The national metereological institute does not measure inside cities as it does not provide data that can be compared with other measurements across the country. By building a dense grid of sensors across the city it becomes possible however to track the emergence of ‘heat islands’ or see how paving over gardens or making them greener influences the city’s microclimates.

The sensor-hub I built this afternoon is based on Arduino, and uses LoRaWan, by means of the The Things Network, to communicate. It currently holds sensors for temperature and humidity, but is prepared to also measure sunlight exposure, rain fall and soil humidity / aridity. It also has a GPS antenna, to capture the location of the device correctly.

It had been a good while since I last handled a soldering iron, but following the ‘fit for all’ building instructions after a while I ended up with a ready device. After loading the right software, it became sensor 51 in the Measure Your City network. The second stage was building a hut for the sensor device, so it measures adequately: shielded from direct sunlight, with air allowed to float around it. This so it matches up with the standards that normal metereological measurements adhere to. After a few hours me and half a dozen or so others had their own sensor-hut to install at home.


the finished device


the hut for the sensors

I haven’t properly installed the device yet: the hut still needs a white coat of paint to reflect sunlight, before mounting it in our garden at about 2 meters height. It is already taking measurements however, and it can be followed through the online database of the network’s measurements. If you look at the current data for my sensor 51, you see it also hasn’t measured its location yet. If that persists as I properly mount it outside, there might be something wrong with the GPS antenna. The temp readings are still in-house readings, and do not reflect outside temperatures.


hello world: first data log entries

I will be running a The Things Network gateway in the near future (when the Kickstarter project delivers) as well, and helped initiate a LoRaWan/The Things Network group in my previous home city Enschede. Building this sensor-hut is the first foray into exploring how I will use that cheap IoT infrastructure currently emerging in the Netherlands. I am looking to add other sensors, along the lines of what e.g. FabLab Barcelona and Waag Society have created with the smart citizen kit, or this project from Freiburg measuring particulate matter in the air.

UPDATE: GPS is working now that the sensor is placed outside. Still need to paint it white though.

Meetjestad.nl sensorhut
Sensor hut in its intended spot in the garden