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ST Developers Conference: Understanding Bluetooth LE as Bluetooth 5 and Bluetooth mesh Loom

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The latest developments in the world of Bluetooth have taught us one thing: understanding the technology is more crucial than ever. This is why Hary Radakichenane will hold a talk on Bluetooth Low Energy at the ST Developers Conference in Santa Clara, California, on September 6. Not too long ago, a popular meme on the Internet was to ask if any gadget or ordinary object “had Bluetooth.” Today, the technology is so ubiquitous we could ask if there are still things that “don’t have Bluetooth.”

Governed by a Special Interest Group (SIG), of which ST is a member, Bluetooth was first developed in 1989 under a different name. At the time, engineers were looking into wireless headsets for mobile phones. Later on, as other manufacturers studied wireless communications between portable devices and computers, the name Bluetooth came up in remembrance of Harald Bluetooth, the king who consolidated Denmark around 960 AD. The idea was that the Bluetooth protocol would unite all mobile devices and one must admit that it has been pretty successful. Smartwatches, smart bands, headsets, medical devices, speakers, keyboards, mice, and many others, have made it a mainstream protocol.

Bluetooth: More Communication, Less Power Consumption

Bluetooth 5

Bluetooth 5 is coming soon

Today, Bluetooth Low Energy (BLE) is the most common flavor of Bluetooth. Officially integrated into the standard in 2010 with the release of Bluetooth 4.0, it uses the same 2.4 GHz frequency as Bluetooth Classic, and thus offers a similar range, but its much simpler modulation significantly reduces power consumption and the cost of the transceiver. BLE is actually so popular that Bluetooth 5, the upcoming protocol, builds on it to double the speed (2 Mbit/s) or quadruple the range (240 meters or 800 feet) while keeping consumption low.

To achieve such a feat, Bluetooth 5 will reduce timings, increase the data rate from one mega symbols per second (1 Ms/s) to 2 Ms/s, and use coded physical (PHY) layers that will increase the range and sensitivity without necessarily aggravating the power consumption. In a nutshell, the new coded layer ensures that the controller transmits more symbols with each bit, which decreases the data rate to 125 Kbit/s or 500 Kbit/s depending on the mode, but offers a much greater tolerance to noise since it’s easier to apply error correction algorithms.

Understanding Bluetooth Today

Very recently, Bluetooth SIG launched Bluetooth mesh, a derivative of Bluetooth LE that can create a mesh network of up to 32,767 nodes. Designed for IoT devices, the 10 Kbit/s ensure the propagation of small messages throughout the network and this system solves the range problem, which makes it a great alternative to sub-Gigahertz networks like 6LoWPAN. As a result, we can see that BLE is alive and transforming the industry with each passing year.

Hence, it is a real treat to have someone like Hary Radakichenane give a talk on the standard’s history as well as the biggest challenges developers face every day. He joined ST 21 years ago and started with the Discrete Group, which manages, among other things, different RF structures. For the past year and a half, Hary has been focusing on Bluetooth LE as the RF Marketing Manager for the Americas. One of his many responsibilities is to meet developers and customers to understand how they implement BLE in their products. As a result, he has amassed a wealth of experience that will greatly benefit the attendants of the Developers Conference.

Power and Flexibility

Bluetooth modules

Diverse Bluetooth modules from ST (click to enlarge)

Bluetooth LE has a special place in ST’s portfolio thanks to powerful components like BlueNRG–1, which consumes very little energy. Furthermore, BlueCoin was one of the darlings of last year’s Developers Conference, and the company has recently updated its STM32Cube BLE software pack in anticipation of this year’s event. However, as we have seen many times, augmenting life means going beyond all expectations to bring something extraordinary. For example, because ST’s BlueNRG-MS was the first device on the market to offer high output power (+8 dBm) despite having a current consumption of only 1.7 µA, new products were suddenly made possible, like the Snuza Pico, which monitors the movements of a baby’s chest to sense distress.

ST also offers real flexibility by providing two kinds of solutions: one with an embedded MCU, like BlueNRG–1 or BlueNRG–2, and one with just an external network controller, like BlueNRG-MS. As a result, engineers only looking to add Bluetooth to an existing design can use the latter without having to learn a new SDK or throw out their existing code. They can also combine BlueNRG with ST’s balun to substantially reduce the need for specialized expertise, which can be a significant advantage for small teams. On the other hand, those hoping for a more comprehensive solution have access to a Bluetooth LE System-on-Chip (SoC), like BlueNRG–1 or 2, which makes it easy to run application code directly from the Flash memory to optimize a design.

Practical Presentation


The main windows of the application STSW-BNRG001 (click to enlarge)

Furthermore, Mr. Radakichenane’s talk will be something extraordinary for engineers because he will walk the audience through the hoops of designing a device with BLE. Hence, this isn’t a presentation about products, but the passing down of practical wisdom from a specialist with years of experience. For instance, he’ll go through the process of implementing the technology. As we sat down with him to discuss his presentation, he emphasized that too often designers are led astray by focusing on the wrong specification. Peak RMS is often the primary focus. However, the vast majority of Bluetooth LE controllers turn on and off to save energy. Hence, the average power consumption is usually a much more appropriate metric when selecting a component.

The session will also go over some of the ST tools that make the developers’ jobs a lot easier, like the STSW-BNRG001, a free software that enables engineers to estimate the power consumption of their Bluetooth solution under different conditions to get information like data rate and battery life estimates. These tools are great to ensure that teams have chosen the right component for their design.

Hary Radakichenane’s talk is “Understanding Bluetooth Low Energy.”