The History of Bluetooth: From Viking Roots to Global Connectivity

 The story of Bluetooth, a ubiquitous technology enabling wireless communication, is a fascinating blend of technological innovation and strategic collaboration. Its name, surprisingly, isn't rooted in technical jargon but in history. It's a tribute to Harald "Bluetooth" Gormsson, a 10th-century Viking king who united Denmark and Norway, mirroring the technology's aim to unite different communication protocols.

The Early Years (Late 1990s): A Necessary Convergence

The seeds of Bluetooth were sown in the mid-1990s. The burgeoning mobile phone industry and the growing popularity of personal computers faced a critical challenge: a lack of a simple, low-power, short-range wireless communication standard. Each device used its own proprietary system, creating a fragmented and incompatible landscape. This hindered the seamless exchange of data between devices.

In 1994, Ericsson, a Swedish telecommunications company, initiated a project aimed at resolving this fragmentation. They envisioned a universal wireless communication solution that would eliminate the need for various cables and connectors. Ericsson collaborated with several other companies, forming the Special Interest Group (SIG) in 1998. This group included IBM, Intel, Nokia, and Toshiba – a powerful consortium with the resources and expertise to develop and promote a new standard.

The Birth of a Standard (1999): The 1.0 Specification

The SIG worked tirelessly to develop a standard that addressed the limitations of existing technologies. The result was the first Bluetooth specification (version 1.0) released in 1999. This version established the core functionalities of Bluetooth, enabling short-range wireless communication between devices. However, early implementations were plagued by range limitations and interoperability issues.

Evolution and Adoption (2000s – Present): A Technological Journey

The subsequent years witnessed rapid advancements in Bluetooth technology. Each new version brought significant improvements in speed, range, power consumption, and features. The crucial 2.0 specification (Enhanced Data Rate) in 2004 dramatically increased the data transfer speed, making it suitable for applications beyond simple data exchange.

Later versions, like Bluetooth 3.0 (High Speed) and 4.0 (Low Energy), further propelled its adoption. Bluetooth Low Energy (BLE), in particular, proved transformative. Its low power consumption enabled its use in a wide range of battery-powered devices, such as wearables, sensors, and health monitoring equipment.

Bluetooth Today: A Pervasive Technology

Today, Bluetooth is ubiquitous. It’s integral to countless devices, facilitating seamless connectivity in diverse applications:

• Wireless headphones and speakers: A dominant application, offering convenience and freedom from wires.
• Wearable technology: Smartwatches, fitness trackers, and health monitoring devices rely heavily on Bluetooth for data transmission.
• Automotive industry: Bluetooth connects smartphones to infotainment systems, providing hands-free calling and audio streaming.
• Internet of Things (IoT): BLE enables connectivity for a vast array of smart home devices and sensors.
• Healthcare: Medical devices utilize Bluetooth for data transmission and remote monitoring.

The Future of Bluetooth:

The Bluetooth SIG continues to innovate, regularly releasing new specifications that enhance performance and functionalities. Future development focuses on increased speed, extended range, improved security, and enhanced power efficiency to support the ever-growing demands of the connected world. The technology's future seems bright, solidifying its position as a cornerstone of wireless communication for years to come.

Design Guide for Scalable Ultra-Low Power Weather Station Based on Bluetooth Low Energy Technology

 

Introduction
This blog post will detail a Bluetooth Low Energy-based system that serves as the foundation for a scalable centralized wireless system consisting of low-power nodes that gather environmental sensor data.

Traditionally, it has been impossible to design a low-power and scalable system that also allows bidirectional communication between end nodes and a central node using Bluetooth Low Energy (LE). However, this is now possible with the right hardware and by utilizing a relatively new Bluetooth feature called Periodic Advertising with Responses (PAwR).

In this project, we will be using Nordic Semiconductor's popular Bluetooth Low Energy platform (including SDK, hardware, tools, and more!). Specifically, we will be using a few nRF52840 development kits.

System Design and Operation

The example project we’ll design and build is a Bluetooth LE-based Weather Station.

For simplicity, we’ll use a single sensor (on each sensor node) that can read both temperature and humidity.

This can easily be expanded to include more sensors or a different sensor that can read other environmental parameters (e.g., barometric pressure, CO, CO2, gas, etc.).

Below is a diagram that shows the different components of the system:

As you can see, our system has three main types of components.

Let’s list each one and describe its role and behavior.

• Sensor Collector:
  • The sensor collector will be very simple in terms of hardware components. It will consist of only an nRF52840 DK without peripherals or additional attached components.
  • This is the “central” node in the system (not to be confused with the Bluetooth LE central role).
  • Instead, this refers to the device acting like a gateway, access point, or hub, meaning the system will not operate without it. The system will be configured in a star topology setup (hub spoke model).
  • The sensor collector’s role is to collect data from all the sensors and expose the data to the user(s) via a smartphone interface.
  • It acts in three LE roles: the PAwR advertiser (receiving data and sending commands from/to the sensor nodes), LE Central (connecting to the sensor nodes), and LE Peripheral (exposing the sensor data to a smartphone app).
  • It will be mains-powered, so no power optimization is needed.
  • The sensor collector stores the last received values and exposes them via a GATT Server that can be read by a connected smartphone.
• Sensor Nodes:
  • In terms of hardware, each sensor node will be made up of the following:
    • nRF52840 DK
    • e-Paper display
    • A temperature+humidity sensor (the Sensirion SHT40)
  • Sensor nodes will act in both LE PAwR synchronized and LE Peripheral roles.
  • PAwR allows the sensor nodes to report the sensor data to and receive commands from the sensor collector.
  • The LE Peripheral role allows the sensor collector to transfer the periodic advertising sync information to each sensor node (via the Periodic Advertising Sync Transfer procedure).
  • This process helps save power on the sensor nodes since they don’t have to go through the process of discovering the PA (Periodic Advertising) train. This might not seem significant, but over time, if the devices repeatedly lose sync and need to re-sync, then power consumption from the PA train discovery process adds up.
  • This device will be battery-powered, so we have to optimize its operation for power consumption.
  • The e-paper display will be used to report three pieces of information:
    • Device ID
    • Temperature reading
    • Humidity reading
    • A sensor node will periodically read both temperature and humidity.
    • It will also print those to the local e-paper display.
  • A Sensor Node will receive commands from the sensor collector.
  • A command will indicate whether it wants to read the temperature or humidity reading.
  • The command will apply to all synchronized Sensor Nodes, and they will all report these values back to the sensor collector.
  • Each Sensor Node will be assigned an ID at compile-time
  • The ID will be included in the advertising data and the responses that are sent back to the sensor collector for identification purposes.
• Smartphone:
  • To mimic a real-world application, we will design the sensor collector to implement an LE Peripheral.
  • This will allow the sensor collector to report the temperature and humidity measurements coming from all the sensor nodes in the system in a unified manner.
  • A connected smartphone can read each sensor node’s latest data, including temperature and humidity measurements.
  • A connected smartphone can subscribe to notifications of temperature and humidity readings from each sensor node and will know exactly which sensor node the readings come from.
  • We’ll use the Nordic nRF Connect for Mobile application to interface (as an LE Central) with the sensor collector.
  • It is recommended to use an Android phone for this purpose due to some necessary features not being available in the iOS version of the nRF Connect for Mobile app.

For the purposes of the project implementation in the course, we will be using only three sensor nodes. However, the system design allows us to scale it to potentially thousands of sensor nodes without having to change much in the architecture. This is the power of PAwR!

💡Note: The full implementation of this project is available in a free course here.

Hardware Components

In terms of hardware components, here’s a complete list of what you’ll need to build the whole project:

Quantity	Hardware Component
4	Nordic Semiconductor nRF52840 DK
1	Nordic Semiconductor Power Profiler Kit II
3	Waveshare 250×122, 2.13inch E-Ink raw display panel
3	Waveshare Universal E-Paper Raw Panel Driver Shield (B)
3	Adafruit Sensirion SHT40 Temperature & Humidity Sensor
3	STEMMA QT / Qwiic JST SH 4-pin to Premium Male Headers Cable Alternative Link (in case out of stock)
1	Glarks 240Pcs 2.54mm Straight Single Row PCB Board Female Pin Header Kit
1	Soldering Iron Kit

Software Components

Here’s a list of the various software components used in the project:

• nRF Connect SDK: we’ll start with v2.6.0, but the course will be updated to support newer versions as they get released.
• Visual Studio Code IDE
• nRF Connect for VS Code Extension Pack
• Third-Party Modules
  • LVGL
  • State Machine Framework
• Various patches that have not been merged into the current SDK version (included in the GitHub repo, linked below)
• nRF Connect for Desktop
• nRF Connect for Mobile

We also have all the source code hosted in a GitHub repo to accompany the course. You can find the repo here.

💡Note: The full implementation of this project is available in a free course here.

Power Consumption Optimization

Achieving low power consumption is crucial for the sensor nodes in our system, especially since they will be running on batteries.

For this purpose, we dedicate a full lesson to optimizing power consumption on the sensor node devices in the course. For this, we employ a few strategies:

• We will use Nordic Semiconductor’s Power Profiler Kit II (PPK2) to measure our application’s current draw and electric charge consumption.
• This is used alongside nRF Connect for Desktop (and specifically the Power Profiler application included within it).
• After the measurement process, we prioritize the device operations based on electric charge consumption (the higher the consumption, the higher the priority).
• We employ a few strategies to optimize power consumption, including turning off peripherals, adjusting how often operations occur, and adjusting the PAwR timing parameters.

💡Note: The full implementation of this project is available in a free course here.

Video Demo

Course Prerequisites

• [Required] Nordic DevAcademy nRF Connect SDK Fundamentals course
• [Required] Nordic DevAcademy Bluetooth Low Energy Fundamentals course

My Honest Thoughts On The nRF Connect SDK

Even though this is a sponsored course and blog post, you may already know that I’ve been working with Nordic Semiconductor’s solutions and ecosystem long before they sponsored any of my work.

So, I wanted to weigh in with my honest personal opinion on the whole nRF Connect SDK ecosystem:

• Pros
  • A comprehensive collection of tools that are well-integrated and streamlined.
  • Integrated with Visual Studio Code, which is fast, modern, and user-friendly.
  • The availability of third-party modules helps you focus on designing and developing the more important parts of your application rather than reinventing the wheel!
  • The solution’s modularity helps you keep your application organized from a source code perspective and makes it easy for teams to collaborate on projects.
  • The solution is updated regularly with new features and bug fixes, which gives you confidence that you’re working with a robust and up-to-date ecosystem.
• Cons
  • It can have a steep learning curve in the beginning.
  • However, it becomes a hard-to-give-up ecosystem once you are past the learning curve and up and running.
  • Also, it helps that there are numerous resources available to help make the learning process faster and easier:
    • Nordic DevAcademy nRF Connect SDK Fundamentals course
    • Nordic DevAcademy Bluetooth Low Energy Fundamentals course
    • Nordic DevAcademy nRF Connect SDK Intermediate course
    • Novel Bits Bluetooth Developer Academy

So, overall, this is my verdict:

The nRF Connect SDK is a pleasure to work with, and its advantages far outweigh the challenges you may encounter at the beginning of the learning journey. Once you get used to it, you want to keep on using it for every project from thereon!