Friday, 9 October 2020

Droidcon EMEA 2020

I was a speaker this year's online Droidcon EMEA conference and discussed issues such as the factors which affect application data rate, what really constrains range in Bluetooth communication (and how to increase it) and how Android developers can create applications with which to monitor and control Bluetooth mesh networks.

You can download my slides from here.

Educational resources for developers and other technical roles can be found at the Bluetooth SIG web site in the resources section, here. Note that code for the demonstrated Bluetooth mesh proxy application for Android, iOS and web is available in the study guide entitled "An Introduction to the Bluetooth Mesh Proxy Function".



Wednesday, 22 April 2020

Droidcon Italy Webinar #1

We're in the midst of a global pandemic. People are isolated, working from home or.... just isolated. Conferences everywhere have been cancelled.

But Synesthesia, the company behind the excellent Android developer conference, Droidcon Italy didn't let that stop them. The annual conference itself was rescheduled to 27th/28th November, but to satisfy those of us hungry for knowledge right now, Synesthesia, working with the Bluetooth SIG also launched a series of webinars so that developers could get together virtually and listen to speakers share their knowledge on a range of topics, over the course of the summer.

I've been a speaker at Droidcon Italy a few times and covered a number of different aspects of Bluetooth. Yesterday, I was glad to have the opportunity to deliver the talk I'd created specifically for this year's Droidcon Italy, entitled "Advanced Bluetooth for Android Developers".

I talked about data rate, what it means and how to maximise it when transferring data between two devices using Bluetooth Low Energy (LE). There are various APIs available to Android developers which can be used to exercise key variables in how Bluetooth is working underneath those APIs. I reviewed those variables and the associated APIs and hopefully gave the audience a much deeper knowledge of what's really going on under the hood, what to expect from those APIs and exactly what can be achieved using them. I presented my own test results, where for example, transferring 100k of data took about 10 seconds using default settings but was reduced to about half a second with a larger ATT MTU, faster connection interval, the LE 2M PHY and two devices which support the LE Data Packet Length Extension feature.

I talked about range. There are many people who still think that Bluetooth has a range of about 20 metres. In fact it's now over a kilometre, especially since Bluetooth 5 introduced the LE Coded PHY, which uses Forward Error Correction to increase receiver sensitivity. Android has APIs that lets you use this feature so that you can maximise communication range. There's some good high level information at the Bluetooth SIG web site about this topic:  and a deeper review in a paper about Bluetooth 5:

I also explained how broadcasting can be performed with Bluetooth LE so that communication is between one transmitting device and an unlimited number of receiving devices, what Advertising Extensions are, how they work and how they can be used.

I looked at Bluetooth mesh briefly, focusing on the fact that Android developers can create applications for the monitoring and control of devices and systems in a Bluetooth mesh network, using something called the Proxy Protocol.

Finally, I talked about the future. Platforms and APIs always lag behind the Bluetooth specifications. There are a number of exciting new capabilities in the Bluetooth core specification which have been released over the last year or so, which we may see appearing on Android and other platforms at some point. Key amongst them are Direction Finding using AoD (Angle of Departure) and LE Audio, the new Bluetooth audio technology which uses Bluetooth LE rather than the older Bluetooth BR/EDR, has a higher quality codec, supports multiple concurrent content streams, private or public audio sharing via audio broadcast and is designed for hearing aids. And sitting under LE Audio in the Bluetooth core stack in a feature called Isochronous Channels, which has potential utility beyond audio use cases. It allows time-bound data to be communicated to multiple devices concurrently, but acted upon (e.g in the case of audio, rendered) simultaneously.

My presentation slides are here:

I'm going to be delivering a second talk, on Bluetooth mesh later in the year. Hope you can make it.


Friday, 29 March 2019

Smart Home for Connected and Assisted Living

On Tuesday 26th March 2019, I was the keynote speaker at this event. I chose to talk about Bluetooth mesh but opened with some thoughts on what exactly the word "smart" might mean. How do we recognise the truly smart from the not so smart gadgets? And as a technical architect, how do I personally proceed in identifying the key issues leading to me making foundational smart home technology choices, which allow me to create a building which is smart today, but which can become smarter tomorrow as my requirements evolve and technology advances?

My presentation is available for download here.

Standing room only!

Friday, 21 December 2018

AmsterdamJS Meetup

AmsterdamJS is a popular meetup for web developers, held regularly in.... you guessed it... Amsterdam. I was a speaker there on 6th December and gave a talk on Web Bluetooth with a little bit of Bluetooth mesh thrown in.

I *tried* to do a number of live demos... with mixed results! I was reliant on the event's very flaky Wi-Fi / internet connection, which unfortunately gave out on me and prevented me from showing my Bitty Software controller demo. I also got hit by a loose battery connection which stopped my first mesh demo working at the first attempt (and nearly gave me a heart attack!). After fiddling with the battery connector, it worked though. In fact the mesh demo worked mostly very well despite having traveled in the hold of the plane and having been very much bumped around. Anyway... here it is.

Saturday, 10 November 2018

Embedded Linux Conference

A couple of weeks ago, I was a speaker at the Embedded Linux Conference in Edinburgh. This is an *excellent* event... if you're into that kind of thing. Which I am.

I spoke about Bluetooth mesh and included a live demo of a "thing" I made and have been tinkering with for a while. As demos go... it's not bad but I still need to find the time to finish testing and implementing a few optimisations. Geting there though.

The demo is a 8 x 8 grid of BBC micro:bits, all running the Zephyr OS and with the Bluetooth mesh generic onoff server and generic level server models implemented (by me) on each. I control the grid, or specific parts of it, identified by the various group addresses I used, from another micro:bit acting as a generic onoff client and from a Web Bluetooth application via an nRF52 which is acting as a Bluetooth mesh proxy node.

Anyway. Enjoy the talk!

Thursday, 23 August 2018

Bluetooth mesh developer workshop

Last night, on August 22nd 2018, I ran a Bluetooth mesh developer workshop, hosted by Skills Matter in London.

In truth, this was a pilot for when I run the same or a similar session at Bluetooth World in Santa Clara, in a few weeks time. I told the attendees they were guinea pigs in my evil experiment and happily, they were a good bunch with no particular problem with being likened to rodents.

Each attendee was given a free BBC micro:bit. This may have helped.

I ran through some basic theory to give each person the required foundational knowledge, focusing on "the essentials" from what is after all, a fairly big topic. I then illustrated some of the concepts with a live demonstration, involving a 66 node Bluetooth mesh network. It consisted of 64 BBC micro:bits, a nRF52 DK acting as a mesh proxy node and my laptop running a web application and using the Web Bluetooth APIs to communicate with the proxy and through it, the rest of the network. I'm happy to say it worked rather well, too!

After that, we turned our attention to the question of how firmware for Bluetooth mesh devices might be developed. I used the Zephyr RTOS as an example SDK which supports Bluetooth mesh and the class worked in teams towards having one micro:bit acting as a light switch, running the mesh generic onoff client model and another micro:bit acting as a node (maybe a light) which can be switched on or off through running the generic onoff server model.


I'd hoped we could get more coding done but my estimates of timing turned out to be a bit on the "optimistic" side. The positive side of this was that I had a great collection of people who asked question after question during the theory part, which I was really happy about.

The slides I used (with a few tweaks since yesterday) are here

A video of the entire workshop is here

Another which may be of interest:

Bluetooth mesh for Android developers

The official Bluetooth SIG web site has some great resources including presentation recordings but the one that budding mesh developers should download is the Bluetooth Mesh Study Guide which provides extensive hands on experience through a series of tutorials based around the Zephyr SDK.

A big thank you to my very nice guinea pigs and to Skills Matter for hosting!