New Bluetooth LE Book

There’s a new book Develop your own Bluetooth Low Energy Applications by Koen Vervloesem. It introduces Bluetooth Low Energy and shows how to programming with Python and the Bleak library on a Raspberry Pi or PC, with C++ with NimBLE-Arduino on Espressif’s ESP32 development boards and with C on Nordic Semiconductor’s nRF52 boards.

Koen has a blog where you can read an abridged version of the book. He explains Bluetooth Low Energy, the Bluetooth stack, advertising and connecting. You can also view the samples on GitHub.

Python and Bluetooth on Linux

Barry Byford has a new blog post on D-Bus and Bluez. It documents his experiences creating a BLE central client on Linux. Barry deliberates over dbus-python and pydbus. He then provides an example how to create a Bluetooth GATT connection, converting D-Bus typed data to python types and interacting with a BBC micro:bit.

While you are on Barry’s site, read his notes from workshops and further notes on using Bluetooth.

Beacon Re-Designs

We are increasingly seeing beacon manufacturers providing updated versions of their beacons, not to provide extra functionality but to instead simplify the designs so as to reduce the component count or use fewer or cheaper semiconductors. The semiconductor manufacture crisis has resulted in a shortage of semiconductors that has resulted in component shortages and price rises. Beacon re-designs are an attempt by manufacturers to keep prices lower and in some cases prevent an existential crisis for a particular beacon model.

System on a Chip (SoC)

Some manufacturers are using simpler versions of the System On a Chip (SoC). These typically have less memory or have less functionality. Often the more-capable functionality wasn’t even used in the older beacon variant. Other times, things can be done in software that were performed in hardware. There’s also a trend to remove crystals that provide timing and instead perform this in software. Some manufactures are switching between SoC hardware manufacturers, for example from Nordic to Texas Instruments that requires a total hardware and software re-design.

Care needs to be taken when purchasing beacons especially when purchasing just a few samples and much later purchasing a larger quantity. Changes in hardware design mean that you won’t necessary get the same behaviour. This can affect aspects such as range and battery life. Doing things in software rather than hardware often affects battery use. At BeaconZone we are taking special care to ensure that current stocks of items behave as previously, if necessary specifying a particular variant when re-stocking.

Introduction to Bluetooth Direction Finding

The Bluetooth SIG, the owner of Bluetooth standards, has a useful video introduction to Bluetooth® Location Services and High-Accuracy Direction Finding. It’s the 4th video from Embedded World 2020. Strangely, you need to view direct from the Bluetooth SIG site because this video isn’t available direct from Vimeo.

Martin Woolley, Senior Developer Relations Manager, provides a high level overview and explains how direction finding differs to positioning using RSSI signal strength. He describes how Bluetooth Angle of Arrival (AoA) and Angle of Departure (AoD) make use of multiple angles to provide accurate location.

Martin dives deeper into direction finding theory and phase sampling. He explains how Bluetooth uses Frequency Shift Keying (FSK) of the radio carrier signal that necessitates use of a Constant Tone Extension (CTE) to enable direction finding. It’s explained how Bluetooth Controller IQ sampling fits into the Bluetooth stack.

View G2 AoA Gateway Kit

Read about PrecisionRTLS™

Fingerprinting Positioning Using Multiple Advertising Slots

There’s interesting research from Spain on Multi-Slot BLE Raw Database for Accurate Positioning in Mixed Indoor/Outdoor Environments. It looks into fingerprinting with beacons simultaneously advertising six slots rather than one slot.

Fingerprinting is where you first measure the signal levels at various known points and then later compare new data with the old to work out the position. This is usually performed with one signal from each beacon. The researchers increased this to six signals to attempt to improve positional accuracy.

Tests were performed at the campus of the University of Extremadura in Badajoz in the Physics and Mathematics buildings and also outside. Beacons were set up to transmit four slots using the Eddystone protocol and two using the iBeacon protocol. Different transmit powers were used for each slot. Measurements were performed using three different smartphones with a custom developed Android application. The resultant data is available on Zonodo.

The researchers compared a simple Nearest Neighbours algorithm (NN) using all the slots, the one slot with the highest transmission power and the average of all slots from the same beacon. The results showed that using all the slots or just one per beacon gives similar results for accuracy, floor, and Tag ID recognition. Results using the averaged values increased the accuracy by 10%.

New Silicon Labs Bluetooth Direction Finding Design

Silicon Labs has a new range of Bluetooth System on a Chip (SoC), the EFR32BG22 (BG22) boasting power efficiency with up to ten years on a coin cell battery. It supports the Bluetooth 5.2 specification, Bluetooth direction finding and Bluetooth mesh. The Bluetooth direction finding provides Bluetooth Angle of Arrival (AoA) and Angle of Departure (AoD) capabilities with sub-one-meter location accuracy.

Silicon Labs have announced a new direction finding kit with a 4×4 antenna array board for evaluation and development. Note that this is a reference design rather than a product that can be rolled out.

The antenna array design and user guide make interesting reading if you want to learn about AoA hardware design.

Many of our customers have misconceptions about direction finding reference design kits. They exist to prove direction finding and are intended as a base design on which to create your own custom hardware using the same components. They aren’t intended for rollout as they generally aren’t physically robust and also don’t have software that will scale to more than a few assets.

Instead, see the Minew AoA kit for a production product.

Read about PrecisionRTLS™

Using Beacons in Building Information Modelling (BIM)

The Journal of Information Technology in Construction has a new new paper on BIM Integrated Post-Occupancy Evaluation System for Office Buildings (pdf). It describes a system that enables conducting space-time queries and visualization of collected feedback to support effective decision-making in facilities management (FM).

The system collected occupant feedback on their comfort needs along with the contextual information and presented this to facility managers. This data is critical for assessing occupant satisfaction and for identifying the operation and maintenance (O&M) issues in good time so as to improve resource efficiency in buildings.

Bluetooth beacons were used for locating the occupants which has the advantages of wide range of usage, low cost and being simple to use. Beacons had to be placed so that they were not obscured by the building elements and signal levels were adjusted to avoid interference between the beacon signals.

The system demonstrated that such systems are practical, usable and that real-time building performance data can be collected and analysed.

Who Controls Your Beacons?

One of our most popular FAQs is

“Which Beacons Don’t Require Registration/Login/Subscription to a Platform to Configure Them?”

Conversations with our customers are showing that people are starting to become wary of beacons that require online logins because:

  • They can’t be administered ‘in the field’ where there might be no connectivity
  • They can’t be easily used with other people’s platforms
  • They tie you into platform availability that you can’t control
  • They tie you into future changes of platform subscription model you can’t control

None of our beacons require you to register, login or subscribe to a proprietary platform to administer them. All can use stand-alone apps for configuration.

Beacon Jewellery as a Personal Security device

IT World Canada recently reported Telus launches personal security beacons disguised as jewellery.

A problem with beacons is that they tend to look ugly when worn. Telus have solved this problem and have developed an app and service so they can be used as a SOS lifeline.

The Telus SmartWear looks like jewellery or a keychain. It connects using Bluetooth to a smartphone. When the back of the charm is double clicked it sends a alert. Telus will ring you back to confirm you need help and, if necessary, send emergency services.