Building Bluetooth Low Energy Systems: Take your first steps in IoT

The idea of a modern day Internet of Things is not significantly old. In 2013, the perception of the Internet of Things evolved. The reasons being the merger of wireless technologies, increase the range of wireless communication and significant advancement in embedded technology. It was now possible to connect devices, buildings, light bulbs and theoretically any device which has a power source and can be connected wirelessly. The combination of electronics, software, and network connectivity has already shown enough marvels in the computer industry in the last century and Internet of Things is no different.

Internet of Things is a network of connected devices that are aware of their surrounding. Those devices are constantly or eventually transferring data to its neighboring devices in order to fulfill certain responsibility. These devices can be automobiles, sensors, lights, solar panels, refrigerators, heart monitoring implants or any day-to-day device. These things have their dedicated software's and electronics to support the wireless connectivity. It also implements the protocol stack and the application level programming to achieve the required functionality:

An illustration of connected devices in the Internet of Things

Internet of Things is fascinatingly spread in our surroundings and the best way to check it is to go to a shopping mall and turn on your Bluetooth. The devices you will see is merely a drop in the bucket of the Internet of Things. Cars, watches, printers, jackets, cameras, light bulbs, street lights, and other devices that were too simple before are now connected and continuously transferring data. It is to keep in mind that this progress in the Internet of Things is only three years old and it is not improbable to expect that the adoption rate of this technology will be something that we have never seen before.

The last decade tells us that the increase in the Internet users was exponential where it reached the first billion in 2005, the second in 2010 and the third in 2014. Currently, there are 3.4 billion Internet users in the world. Although this trend looks unrealistic, the adoption rate of the Internet of Things is even more excessive. The reports say that by 2020, there will be 50 billion connected devices in the world and 90% of the vehicles will be connected to the Internet. This expansion will bring $19 trillion in profits by the same year. By the end of this year, wearables will become a $6 billion market with 171 million devices sold.

As the section suggests, we will discuss different kinds of IoT devices available in the market today. The section will not cover them all, but to an extent where the reader will get an idea about the possibilities in future. The reader will also be able to define and identify the potential candidates for future IoT devices.

Wearables

The most important and widely recognized form of Internet of Things is wearables. In the traditional definition, wearables can be any item that can be worn. The wearables technology can range from fashion accessories to smart watches. Apple Watch is a prime example of wearables. It contains fitness tracking and health-oriented sensors/apps which work with iOS and other Apple products. A competitor of Apple Watch is Samsung Gear S2 which provides compatibility with Android devices and fitness sensors. Likewise, there are many other manufacturers who are building smart watches, including Motorola, Pebble, Sony, Huawei, Asus, LG and Tag Heuer. The reason that makes them a part of the Internet of Things is that they are more than just watches. It can now transfer data, talk to your phone, read your heart rate and connect directly to Wi-Fi. For example, a watch can now keep track of your steps and transfer this information to the cell phone:

Fitbit Blaze and Apple Watch

Smart home devices

The evolution of the Internet of Things is transforming the way we live our daily lives. People have already started using wearables and many other Internet of Things devices. The next big thing in the field of the Internet of Things is the Smart Home. Home Automation or simply Smart Homes is a concept when we extend our home by including automated controls to the things like heating, ventilation, lighting, air-conditioning, and security. This concept is fully supported by the Internet of Things which demands the connection of devices in an environment. Although the concept of smart home came on the surface in the 1990s, it hardly got any significant popularity in the masses. In the last decade, many smart home devices came into the market by major technology companies.

Amazon Echo

One of the important development in the world of home automation was the launch of Amazon Echo in late 2014. Amazon Echo is a voice-enabled device that performs tasks just by recognizing your voice. The device responds to the name Alexa, a keyword that can be used to wake up the device and perform tasks. This keyword can be used followed by a command to perform specific tasks. Some basic commands that can be used to fulfill home automation tasks are:

• Alexa, play some Adele.
• Alexa, play playlist XYZ.
• Alexa, turn the bedroom lights on (Bluetooth enabled lights bulbs (for example Philips Hue) should be present in order to fulfill this command).
• Alexa, turn the heat up to 80 (a connected thermostat should be present to execute this command).
• Alexa, what is the weather?
• Alexa, what is my commute?
• Alexa, play audiobook a Game of Thrones.
• Alexa, Wikipedia Packt Publishing.
• Alexa, how many teaspoons are in one cup?
• Alexa, set a timer for 10 minutes.

With these voice commands, Alexa is fully operable:

Amazon Echo, Amazon Tap and Amazon Dot (from left to right)

Amazon Echo's main connectivity is through Bluetooth and Wi-Fi. It uses Internet network to run the commands. On the other hand, it uses Bluetooth to connect to other devices in the home. For example, the connectivity to Philips Hue and Thermostat is through Bluetooth.

In Google IO 2016, Google announced a smart home device that will use Google as a backbone to perform various tasks. The device will challenge the power of Alexa on the commercial level. This will be a significant step for Google in the smart home market.

Note

Amazon also launched Amazon Dot and Amazon Tap. Amazon Dot is a smaller version of Echo which does not have speakers. External speakers can be connected to the Dot in order to get full access to Alexa. Amazon Tap is a more affordable, cheaper and wireless version of Amazon Echo.

Wireless bulbs

Philips Hue Wireless Bulb is another example of smart home devices. It is a Bluetooth connected light bulb that give full control to the user through his cellphone. The bulbs can change millions of colors and can be controlled remotely through away from home feature. The lights are smart enough to sync with the music:

Illustration of controlling Philips Hue Bulbs with smartphones

Smart refrigerators

Home automation is incomplete without kitchen electronics and Samsung stepped into this race. Family Hub Refrigerator is a smart fridge that let you access the Internet and runs many applications. It is also categorized in the Internet of Things devices as it is fully connected to the Internet and provides various controls to the users:

Samsung Family Hub Refrigerator with touch controls

Television and online media

Internet of Things marked its victory in the Media Electronics as well. An example of the Internet of Things in this domain is the Google Chromecast.

Google Chromecast

It is a digital media player that converts a normal television into a Smart TV. It is designed as a small dongle that connects through HDMI and uses WLAN to wirelessly connect to the cell phone. It lets you cast YouTube, Netflix, Google Photos and many other applications through your cell phone. Google also launched an audio version of the Chromecast that lets you cast your music to any wired speaker.

The advantage of this technology is that it enables a non-smart electronics device to become smart by connecting it remotely to the cell-phone. Google Chromecast was one of its kind portable device to perform a plug-and-play functionality to any television and audio device. Google Chromecast 2^nd Generation runs 1.2 GHz ARM-Cortez A7 processor with 512 MB of DDR3L RAM.

Note

For a complete list of the applications supported by Google Chromecast, follow the link: https://en.wikipedia.org/wiki/List_of_apps_with_Google_Cast_support.

In the following topic, we will discuss how the industry giant Apple is running the best home entertainment smart device:

Google Chromecast Audio and Google Chromecast (2^nd Generation) from left to right.

Apple TV

While Chromecast provides portability and ease to connect to Android devices, Apple TV runs tvOS (based on iOS) and provides a solid base of the operating system. There are many TV services that provide their services through Apple TV and there is no scarcity of supported applications. It supports Bluetooth, HDMI, Wi-Fi and USB-Type C connectivity. The 4^th Generation of Apple TV features an A8 processor with 2GB RAM and up to 64GB of internal storage.

Note

For a complete list of application supported by Apple TV 4^th Generation, follow the link https://en.wikipedia.org/wiki/Apple_TV#4th_generation_3.https://en.wikipedia.org/wiki/Apple_TV#4th_generation_3

Moving forward, we will discuss how the Internet of Things made its way in the automotive industry with the help of incredible software stack and smart sensors:

Apple TV 4^th Generation

Automotive industry

The discussion on the Internet of Things is incomplete without talking about its impact on the automotive industry. Tesla Motors, a silicon-valley based company was built on the philosophy of smart vehicles. Named after the world's greatest scientist Nikola Tesla, the company sells electric cars, electric vehicle powertrain, and batteries. Tesla Roadster was the first fully electric sports car, launched in 2008. This model was followed by Tesla Model S:

Tesla autonomous driving with GPS navigation on 17" touch screen display

Beginning September 2014, all Model S were equipped with a camera mount on the windshield, forward facing RADAR, and ultrasonic acoustic location sensors giving the car an ability to sense 360-degree buffer. At that time, Model S had the ability to recognize obstacles and road signs. This well-equipped car was given the capability of auto-pilot in October 2015 in the software v7.0 which allows hands-free driving. The update on January (software v7.1) contained "summon" feature that allows the car to park itself automatically without the driver. Another big thing to know here is that the software updates for Tesla are over-the-air unlike some of its competitor. The autonomous driving feature ignites a mixed reaction from the community where some users were excited, others were doubtful about the safety. The update resulted in this car to become a true Internet of Things marvel as it satisfies the requirements perfectly.The car is now fully aware of its surroundings and can make decisions to navigate safely on the road. Industry experts showed concerns regarding the autonomous driving but Tesla CEO and Google's director of self-driving cars showed their confidence in the technology:

Tesla Model S and Model X (from left to right)

Note

Tesla Motors has two models after Model S, Model X and Model 3. While Model X is an SUV style vehicle, Model 3 is the most affordable model.

Wireless Local Area Network or simply WLAN is a network that connects two or more devices wirelessly. A full TCP/IP protocol stack is followed in order to achieve end-to-end communication. This technology is based on IEEE 802.11 standard in which the communication between devices is achieved by a centralized hub/router. The devices are commonly referred to as nodes and the centralized router is referred to as wireless access point. In a usual situation, the wireless access point has a fixed location where the nodes can freely roam around within the coverage area of the access point. The connected devices can be tablet computers, laptops, desktops, cell phones or any IoT device (such as a smartwatch or Google Chromecast). Residentially, a typical access point covers an apartment but in commercial situations multiple access points can be bind to one SSID. If a node travels from Router 1's coverage area to Router 2's coverage area, they will perform a seamless handover between each other. Modern day WLAN are advertised under the Wi-Fi brand name.

Following mentioned diagram shows how Wi-Fi router communicates to its nodes. It is a typical working model of a WLAN:

Wireless Local Area Network architecture

This technology is proven to be very effective in modern day Internet of Things because the architecture is simple and can easily be implemented on a device with limited capabilities. Moreover, IPv6 gives us approximately 3 x 10^38 addresses which are more than enough to give identity to every atom in the world, let alone smart devices.

Wireless Local Area Network is an important technology in the Internet of Things and devices like smart watches, media players and autonomous vehicles often use this technology to transfer information. Sometimes, this technology is used to give a control to the smart devices over a long distance.

Wireless Ad-hoc Networks lies under the umbrella of IEEE 802.11 standard as well but unlike WLAN, they don't have a centralized hub/router. The devices are responsible for routing the packets across the networks. Wireless Mesh Network (WMN) is a sibling of Ad-hoc Networks with the only difference of traffic abnormalities and mobility. Ad-hoc networks are more dynamics as compare to WMN and they have more traffic irregularity than WMN.

In Ad-hoc networks, the device acts as a router to transmit traffic between peers if the destination device is not directly connected to the sender device. This formation of devices is reliable because each device is connected to another device in a mesh, giving alternate routes to any possible incoming packet. These networks are also self-organized, so if a device leaves the network, the network will reconfigure itself for new potential routes for forwarding packets. Due to their architecture, they are widely used in small and large networks. They run on TCP/IP based model and can easily be implemented in any lite-weight smart device.

Since they are connected to one another directly, they are also called peer-to-peer networks. The architecture of Ad-hoc networks is different than WLAN which brings advantage and disadvantage at the same time. Ad-hoc networks are fast and don't contain a single point of failure like a router, but they are more prone to network attacks. Ad-hoc networks are easily scalable networks where devices can come and go at their will. On the other hand, those devices are responsible for routing the packets, which make them weak for Man in the Middleattacks.

Wireless Ad-hoc Networks are further classified into five types:

The inclusion of Ad-hoc networks in the smart device makes them vulnerable because they normally contain personal and sensitive information. This brings a threat to the Internet of Things. On the other hand, Ad-hoc is almost the perfect topology for IoT devices as they are fast, scalable, easily maintainable and cheap.

To understand how a mesh is connected, consult the following figure:

An illustration of a fully connected Ad-hoc Network

ZigBee is a wireless mesh network built on IEEE 802.15.4 standard. With the advancement in sensors and low-powered smart devices, there was a need for a technology that can connect them wirelessly in the form of a mesh. The ZigBee technology was introduced which works on a Personal Area Network and works on low power. Internet of Things searches for the technology with low power consumption because it is built with the devices with limited power capabilities. For that purpose, ZigBee is considered as a technology with a seamless connection flexibility, ideal power consumption, and reliability.

ZigBee gives a 10-100m line of sight coverage for connectivity. Typically, it works on a 2.4 GHz band (ISM) but can be found on other frequency like 784 MHz, 868 MHz, and 915 MHz. With the wide variety in the spectrum, the data rates in ZigBee varies from 20 Kbit/s to 300 Kbit/s. The ZigBee module can be of 0.5 inches which are easily implementable in any Internet of Things device. One of the attractive parts of ZigBee is that it has out of the box capabilities of wireless mesh, star and tree architecture:

ZigBee Logo

A significant disadvantage of ZigBee lies in its adoption in computing devices. Typically, a smartphone or a laptop does not come with this module. Computers and cellular phones are the basic connection points for IoT devices. For example, if a person has ZigBee-based smart-home device, he will not be able to control it with his cellular phone or laptop without connecting additional hardware. This is a very crucial disadvantage as IoT devices mostly, if not always, rely on a smartphone-based remote control. Philips Hue (a smart bulb) can not be remotely controlled by a smartphone if its major technology of communication is ZigBee.

This disadvantage leaves a question mark on the technology but the other side can not be neglected as well. ZigBee is the only lite-weighted-low-power-consumption technology available in the market which supports mesh communication out of the box. Companies like smart plugs and smart energy interface use ZigBee as their main mode of communication. Let's take the example of Philips Hue Wireless dimming kit. It comes with a separate controller which talks to the smart bulb without any need of the smartphone. In this scenario, ZigBee can be the most practical solution.

A demonstration of the Philips Hue smart bulb can be seen here:

Phillips Hue wireless dimming kit with ZigBee technology

From 1999 till 2009, many versions of Bluetooth were released. Solving many problems from the initial release while increase the speed and the connection quality. It was not until the version 3.0 when Bluetooth could achieve a speed of 24 Mbit/s. During this evolution, a continuous change in the protocol stack can be observed to solve various issues in the technology. For example, in Bluetooth v3.0, Logical Link Control and Adaption Protocol (L2CAP) was introduced to multiplex multiple logical connections between various devices using different protocols. Service Discovery Protocol (SDP) was also introduced to connect to the Bluetooth devices like headsets etc. During this period of time, the member companies of Bluetooth SIG rose to 12,000 and by 2010, it surpassed a total of 13,000 companies.

The next step in the history of Bluetooth was a significant one. The SIG decided to take a step back and rethink the protocol stack being used in Classic Bluetooth. Bluetooth Core Specification 4.0 or simply Bluetooth Low Energy came into being in 2011. It was previously known as Wibree by Nokia which replaced the entire protocol stack of the previous technology and concentrated on the speed and the simple architecture. 2011 was the same year when SIG surpassed 15,000 companies, Apple and Nordic Semiconductor joined SIG Board of Directors, Apple released first two computers with Bluetooth 4.0 support and Microsoft announced Windows 8 phone with Bluetooth 4.0 Core Specifications.

Unlike classic Bluetooth, Bluetooth Low Energy focused on the low power consumption. That was a very important step from the SIG as it was realized that in future, the technology will not be just fast but less power hungry as well:

Bluetooth SIG official Logo

Bluetooth v4.1 came as a software update rather a hardware update. The update focused on the usability and implemented Bluetooth Core Specification Addenda. Previously, the Bluetooth radio and LTE radio didn't coexist and resulted in interference. The issue was causing performance issue and fast battery drainage. Bluetooth 4.1 enabled both these technologies to co-exist in one device with high data rates. BLE v4.1 was the first version which enabled any device to become a server and client. On the other hand, the smart connectivity was introduced which let devices manage their power better by enabling manufacturers to define their own reconnection time intervals. The version of Bluetooth was commercially available in early 2013. In the same year, Google also announced the native BLE support to Android.

With power efficiency and server/client flexibility, Bluetooth Low Energy officially stepped into the Internet of Things.

The evolution in the Bluetooth leads us to Bluetooth v4.2. In December 2014, Bluetooth SIG announced the next version of Bluetooth with some special features supporting IoT. Bluetooth Low Energy v4.2 provided flexible Internet connectivity options to achieve power efficiency. IPv6 support was given to the standard with an ability to make Bluetooth Smart Internet Gateway (GATT) architecture. The concept will be discussed in detail later in the chapter.

In Bluetooth 4.2, LE privacy and LE Secure Connections were also introduced by Bluetooth SIG. Two-factor authentication via BLE was introduced to provide better security. The new version also claimed that it is not 2.5 times faster with 10-fold extension in data length. The over-the-air firmware update was also introduced in this version which provides manufacturers to remotely update the firmware without even touching the device. Bluetooth 4.2 is backward compatible with version 4.0 and 4.1 which were also Bluetooth Low Energy.

Bluetooth Low Energy is a standard with millions of devices running it. Discussing Bluetooth Core Specification in full-length is almost an impossible task as it has many technicalities. So the key concepts that will help you develop the Bluetooth Low Energy applications will be discussed in the book.

The layer stack of Bluetooth Low Energy corresponds to the OSI layer. In this book, we will not discuss the lower level layers (that is, from PHY to L2CAP) as they are out of the scope. The main concepts covered in this book will be Attribute Protocol, Generic Attribute Profile (GATT), Generic Access Profile (GAP) and the top layer Bluetooth Application. The book will give practical examples of how to write the Bluetooth Application based on the GATT server/client architecture.

The protocol stack of the Bluetooth Low Energy can be seen in the following figure:

Bluetooth Layered Model

128-bit-UUID = 16-bit-value * 2 ^ 96 + Bluetooth-Base-UUID
128-bit-UUID = 32-bit-value * 2 ^ 96 + Bluetooth-Base-UUID

GATT-based Bluetooth Profile Hierarchy

Generic Attribute Profile describes the structure following which a profile exchange data from one device to another. The basic elements of a profile are services and characteristics. Typically, a profile is made in order to achieve the desired task. Services and characteristics are the main components of a profile which can be described as the subtasks.

The division of the GATT-based hierarchy is given here:

GATT based profile model with services, characteristics, and descriptors.

Service

A service is a collection of characteristics designed to fulfil a particular task. It can also reference another sub-service which then comprises of characteristics. For example, a profile can have a Heart Rate Monitor service which is to expose heart rate for fitness purposes. This service can have Heart Rate Measurement, Body Sensor Location, and Heart Rate Control Point characteristics which are the subtasks of the Heart Rate Monitor service.

Characteristic

A characteristic contains a value, properties, and configuration information. Characteristic is the combination of characteristic properties, characteristic declaration, characteristic value, and a descriptor. Characteristic properties define the level of access that characteristic grants. For example, if a characteristic is read-only it will be defined in the properties. The characteristic declaration can be seen as a characteristic overview where the name, description, type and the requirements of the characteristic is mentioned. Descriptors are used to define a characteristic value.

The following diagram shows a view of the BLE characteristics:

Heart Rate Measurement characteristic with overview, properties, security and descriptor

The example in the figure is describing a Heart Rate Measurement characteristic. The overview describes the functionality of the characteristics and the requirement level. The requirement tells if it is mandatory or optional for the service. The properties show the access-level of this characteristic. In this particular scenario, the characteristic is only used to notify. The descriptor identifies the value or permits configurations of the GATT server with respect to the characteristic value.

Bluetooth Low Energy provides five features for its security including pairing, bonding, encryption, authentication and message integrity. These satisfy three pillars of security which are Authentication, Confidentiality, and Authorization. Attacks against improperly secured Bluetooth implementation can provide hackers with unauthorized access to the sensitive information and unauthorized use of the Bluetooth device. The main security features in Bluetooth Low Energy are:

In the past five years, the work in the Internet of Things is significant in comparison to the previous times. Many manufacturers and start-ups are focusing on this technology in order to make accessories for the smartphones. The reason manufacturers are more focused towards the BLE as compared to any other technology is that they want to increase the adaptability of their IoT devices. As most of the smartphones exist have Bluetooth technology in it, the adoption rate of these accessories is tremendous as compared to any other standard. People want to use their smartphones to control and interact with things. It would be great if they can control the bedroom light from their smartphone or turn off the stove from their cell phone.

The promity sensing, indoor navigation, fitness tracking and other countless applications have already found their way in the Bluetooth Low Energy. Users do not have to sacrifies the battery life while enjoying the connection with their favorite IoT devices. At this moment, it is not clear if the future of IoT lies in the combination of several wireless standards in one device (for example, combining Wi-Fi and BLE both in a single device) or there should be one stand-alone standard which is the master of everything. It is sensible to predict that there is no significant loss if there are multiple standards in one device as the architecture and technology become cheaper. The companies in consumer electronics will not hesitate to go to multi-standard solutions in the longer run.

Bluetooth World event organized by Bluetooth SIG in Santa Clara, United States

Companies like Google, Apple, and Intel are already backing up the BLE standard. The progress and the agreement of the industry can be seen in the work of the Bluetooth SIG because as of June 2016, SIG announced a new version of BLE as Bluetooth 5. Quadrupling the range and doubling the speed will make Bluetooth Low Energy compete more aggressively in the market. In Bluetooth World 2016, which is an annual event organized by the Special Interest Group, many manufacturers were present to show their products. It showed the diversity how companies are changing the way we think about Bluetooth technology. CSRMesh which is acquired by Qualcomm, showed off their mesh technology built over Bluetooth to take this standard to another level and truly threat ZigBee as it is the only standard that provides a low powered mesh architecture.

The modes of communication of Bluetooth Low Energy are already discussed in this chapter that is why it is a good point to introduce the Bluetooth Low Energy Beacons. They are the broadcast only devices that advertise certain information to the users around them. This functionality enables a user to receive information from the beacon and in some cases take actions too. These broadcast happens in a limited proximity and can be changed by modifying the properties of the beacons.

Bluetooth Low Energy Beacon use-case

A use-case of Bluetooth Low Energy Beacons is their implementation in the bus stops. Instead of putting the bus timings on the transit board, it would be better if the bus stop broadcasts this information through Bluetooth. Since BLE is a low power consuming technology, it is completely feasible for the user to receive this information from the bus stop. Another use-case can be the boutique sales. Instead of putting up the banners, shops can broadcast the information through Bluetooth beacons and the shoppers around them receive a notification in their cell-phone about the sale.

The battle between Google and Apple can be seen by these logos:

Apple iBeacon and Google Eddystone logos

The mesh networking is a proven technology in terms of design and scalability. Information Technology has already seen the advantages of this technology in the form of wireless mesh networks, wireless sensor networks, mobile ad-hoc networks and vehicular ad-hoc networks. In the Bluetooth World 2016, SIG showed their interest in the mesh technology and announced that they are working with Qualcomm to build a first generation mesh technology by next year.

The mesh technology is a significant advantage of ZigBee in the latest times because it is fully developed and fully functional mesh mechanism to support upto 65,000 nodes mesh. Bluetooth, on the other hand, does not support mesh technology. By entering in the mesh networking, Bluetooth Low Energy will become powerful enough to replace ZigBee in the commercial industry. Logical prediction can be made that the adoption of the Bluetooth mesh will be much faster as it will be supported by the cellular phones, tablets, and laptops.

A much detailed overview and a practical hands-on approach on the Bluetooth Mesh will be discussed in Chapter 6, Bluetooth Mesh Technology.