Thursday, February 11, 2016

SIGFOX Makers tour Lisbon

I just spent the afternoon at SIGFOX’s event in Lisbon, learning about the company offering and doing some hands-on demos with an Arduino Uno and SIGFOX’s network.
What is SIGFOX? To be honest, I didn’t exactly know, when I got the Meetup email from Productized about the event. SIGFOX is an telecom operator, exploring a range of radio frequencies and a kind of modulation (UNB – Ultra-Narrow Band) that makes it especially interesting for the IoT world.

Up until today, my only experience with IoT was with the Raspberry Pi, and the code to handle the wifi connectivity in case of failures has given me several headaches. It seems bluetooth, which is more widely used with Arduinos, is also not a simple process, due to the need to pair, for example. SIGFOX’s network promises several advantages in this area: simplicity in sending (and receving messages) from the network is a question of doing a send call – no need to pair, connect, authenticate, etc. There are base stations (much like in GSM) that get the message, de-duplicate it, make it reach SIGFOX’s infrastructure, and either process it there or route it to our own application server via an HTTP call. Another major selling point is the low power usage: the protocol used is designed to maximize energy efficiency and use energy only when needed - essentially, it uses 20-35mA when sending messages, and the chip is supposed to be in standby most of the time, when not communicating – the communications pattern assumes the device polls for incoming commands when required/regularly. A solution using this approach is supposed to have up to have several years of autonomy, supposedly.

This simplicity and low power consumption, clearly major selling points, are offset by some limitations in the range of applications: messages have a payload of 12 bytes (xml and json are out, as are applications regarding media transmission) – this means you’ll be optimizing messages on the bit level; additionally, to comply with european regulations in the usage of the spectrum, you can only send up to 140 messages per day (about one message every 10 minutes), and finally the transmission rate is pretty low: 100 bits/sec – so it pays to keep messages as small as possible. Even with these limitations, it’s pretty clear there is a wide range of applications for this approach – my Raspberry Pi temperature setup uses Wifi and is constantly plugged in, a SIGFOX+Arduino solution would probably just require batteries.

Interestingly, there is already network coverage in Portugal (an in the Netherlands, France and Spain – as well as several other major cities worldwide), and prices are supposed to be very affordable (2€ to 25€/year, if I understood correctly), depending on factors such as usage. In one of the demos, a message sent by the board was picked up by 4 base stations – the workshop was in the city’s downtown.
The platform has mechanisms (callbacks) that can handle requests from the devices, either semi-automatically by parametrizing preset responses (ex: return the current time), or by making HTTP calls to a configured application server on our end. Interestingly, Azure Event Hubs (which I also use in the Raspberry Pi tests) are also natively supported, with the network automatically posting incoming messages from devices into a configured event hub – and the Azure IoT Suite will also be supported.

I thoroughly enjoyed the afternoon in the workshop, and was surprised at how easy it was to use the network and the Arduino. I’d seen demos of Arduino before, and to be honest was not looking forward to be back in coding C, but it was easier than it thought (I still have this book around, from when I learned the language in high school).

As to doubts and issues: IoT security seems to be in the news every day, so this is obviously a concern. I don’t know much on the topic, but device authentication, server authorization, and server authentication in the device seem obvious concerns. The trainer, Nicolas (great job!), didn’t have much time so he didn’t expand on the topic (and I still don’t have the slides with me), but it is a concern I’ll have to explore.

The SIGFOX demos done in the workshop are available on GitHub. The board provided can read the temperature (with a degree resolution), so I might do the exercise of converting my C# code from the Raspberry to run on the Arduino.

PS: I have very basic electricity/electronics know-how, and somehow see myself with a couple of Raspberry’s, now an Arduino, and several sensors, cables and breadboards on the way from AliExpress. What is happening to me? :-)


  1. Hi João, you may find additional and more technical information on SIGFOX here:

    Check also the DASH7 technology, also very interesting...


  2. I also found a couple of other interesting links:

    This is the board given away in the workshop:

    This 2014 post on using Sigfox is also very interesting: