Bluetooth: Part 1

Written by Jeremy Loslaw, Eventys

There are more Bluetooth enabled devices in the world than there are people. Such is the importance and widespread adoption of the short range wireless technology that more than 2 billion Bluetooth products have shipped each year since 2013, topping out at approximately 4 billion devices last year and still growing. It is a technology that has gained widespread adoption and has a massive influence on our daily tech lives. It is the core technology that powers so many of our devices from the ubiquitous speakers and headsets and headphones to phones, keyboards, mice, lights, door locks, fitness trackers, and other smart devices. Seated at my desk as I write, I count no less than 6 Bluetooth enabled products in my immediate field of view.

The ubiquitous Bluetooth speaker allows us to listen to tunes anywhere in the world…. Within 30 feet of phones.

It is a powerful technology that allows devices of disparate design to communicate with each other. Apple can talk to Fitbit. Samsung can talk to Sony. Because it is device agnostic and versatile, it has become the de facto wireless technology of so many smart devices. Since it is ubiquitous and has been adopted world wide, product developers and prototypers need to know how it works, when and how to use it, and how to build prototypes that use it. In this two part series, I will discuss the history and core concepts around Bluetooth before delving into details of the communication protocol and easy ways to create Bluetooth enabled prototypes.

Bluetooth is a wireless communication standard for peer to peer device communication. It is meant for generally short range personal area networks (PAN) for devices to communicate with each other. Bluetooth can carry different types of payloads such as sensor data, sound, and even video. The range is usually about 30ft which is perfect for speakers and headphones which are one its most popular uses, but depending on the device setup can be anywhere from 1-1000 meters. Bluetooth comes in two different flavors, Bluetooth classic and Bluetooth Low Energy (BTLE), more on this later, and as of this writing the latest release of the standard is Bluetooth 5.2. It uses a frequency of 2.4GHz which is the same as WiFi. However it has lower bandwidth and range and thus has lower power requirements than WiFi and it is viable to run Bluetooth devices from battery power whereas WiFi devices usually need to have access to continuous wall power. The name Bluetooth is a reference to the 10th century king of what is now Denmark and Norway, Harald “Bluetooth” Gormsson. He was known for uniting Nordic tribes under a common kingdom, which is a fitting given that Bluetooth technology helps to unite different devices under a common standard. The angular Bluetooth logo is an amalgam of the runes of Haralds initials.

The Bluetooth logo is a reference to King Harald.

While Bluetooth devices have been popular in consumer applications for about the last decade, the development of protocol has its roots in the 90s. Researchers at Swedish technology company Ericsson were the first to develop the short range wireless communication technique using UHF (ultra high frequency) radios. Jaap Haartsen is listed on many of the early patents and considered the grandfather of the technology. The original goal was to find a wireless alternative to RS-232 cables which use a 9-pin connector and were commonly found on printers more than a decade ago. They were also a common way to transmit data between computers and devices and are still used sometimes in industrial applications. 

It was these pesky RS-232 cables that Bluetooth was conceived to get rid of.

It was not until the turn of the millennium that Bluetooth was ready for the consumer space. The first Bluetooth product was a hands free headset, a sort of precursor to the ubiquitous jawbone style earbuds. It was launched at COMDEX, the Computer Dealers’ Exhibition tradeshow in 1999 and won Best of Show. Two years later, the Sony Ericsson T39, a flip phone with the classic early oughts monochrome screen became the first cell phone with Bluetooth inside to make it to store shelves. 

The launch of the first Bluetooth devices coincided with the publication of the Bluetooth 1.0 standard in 1999. This paved the way for Bluetooth chips to become available to device makers and they were immediately integrated into many different types of products. The first standard allowed for maximum data speeds of just 721 kbps, but in application this was often much lower. Since then, there have been four additional top level releases of the Bluetooth standard. Bluetooth 2.0 upgraded the core transfer speed to 1Mbs and increased max range from 10 to 30 meters as well as easier pairing. Bluetooth 3.0 offered an optional high speed data transfer that actually used WiFi to boost transfer speeds to 24 MBs. Bluetooth 4.0 is the first version where there is a differentiation between Bluetooth Classic and Low Energy and it improved maximum range to 60, and has better IoT device support. This brings us to Bluetooth 5, which was launched in 2016 which added longer range as well as low energy support for audio devices. Despite the number of upgrades and enhancements to the protocol the core data rate is set to 1Mbs which allows for maximum backward compatibility for legacy devices.

It has been 20 years since the launch of the first Bluetooth enabled cell phones and devices, and the technology has matured from being a quirky tech feature to a mainstream and globally used protocol. Where the devices were once very finicky, hard to connect and prone to losing connection, they are now easy to use and friendly to use for the un-tech savvy users. It is resident in our homes and our cars, and new generation phones easily connect to devices anywhere in the world. With the advent of the low energy standard we are seeing new types of devices that can live off of a single battery for 5 years or more and can thus be put into harsh or relatively remote environments. They are also being leveraged in retail environments where Bluetooth beacons can notify our phones of flash sales or provide additional product information. The applications are endless and any new product that is electrified needs to at least consider adding Bluetooth to its featureset. Because of how useful and widespread the technology is, prototypers and product developers need to be comfortable with how it works. In part two I will explore in more detail how Bluetooth devices communicate with each other and some easy ways to prototype them.

In part 2, we will learn about quick ways to prototype Bluetooth enabled devices.

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