Getting Started with Bluetooth Low Energy: Tools and Techniques for Low-Power Networking

by Kevin Townsend, Carles Cuf, Chris Wang, Robert Davidson

Overview

With Bluetooth Low Energy (BLE), smart devices are about to become even smarter. This practical guide demonstrates how this exciting wireless technology helps developers build mobile apps that share data with external hardware, and how hardware engineers can gain easy and reliable access to mobile operating systems.

This book provides a solid, high-level overview of how devices use BLE to communicate with each other. You’ll learn useful low-cost tools for developing and testing BLE-enabled mobile apps and embedded firmware and get examples using various development platforms—including iOS and Android for app developers and embedded platforms for product designers and hardware engineers.

• Understand how data is organized and transferred by BLE devices
• Explore BLE’s concepts, key limitations, and network topology
• Dig into the protocol stack to grasp how and why BLE operates
• Learn how BLE devices discover each other and establish secure connections
• Set up the tools and infrastructure for BLE application development
• Get examples for connecting BLE to iPhones, iPads, Android devices, and sensors
• Develop code for a simple device that transmits heart rate data to a mobile device

Product Details

ISBN-13:	9781491949511
Publisher:	O'Reilly Media, Incorporated
Publication date:	05/26/2014
Pages:	178
Product dimensions:	7.00(w) x 9.20(h) x 0.20(d)

About the Author

Kevin Townsend specializes in embedded design and development around the ARM Cortex M family of microprocessors, and has a long-standing interest in low-power wireless communication. He's active in the open source hardware world as lead engineer at Adafruit Industries, where his job is taking interesting technologies in the embedded engineering space and getting them into the hands of domain experts in other fields to see what interesting solutions they can come up with when technology becomes invisible.

Carles Cufí has been involved with Bluetooth since the year 2000. Starting at Parrot in Paris with version 1.0 of the specification, he wrote one of the first protocol stacks to be shipped on a commercial product, and he has been involved with the development and implementation of Bluetooth devices and systems ever since. He is currently employed by Nordic Semiconductor, where he is responsible for the Bluetooth Low Energy Application Programming Interfaces offered to the developers using the nRF51 family of Integrated Circuits.

Akiba has been involved in wireless sensor networks since 2003. He wrote FreakZ, an open source Zigbee protocol stack, and also Chibi, an open source 802.15.4 protocol stack. He's a researcher for Keio Universityin the Internet and Society research group, and is a design consultant to the United Nations. His specialty and interest is in sensor networks for environmental monitoring. He currently runs FreakLabs, an open source wireless company, and is working on a hackerspace in the Japanese countryside called Hackerfarm.

Robert Davidson’s passion in life is to apply what he knows about technology to solve real problems for people. He especially enjoys applications that use sensors to connect the physical world to computers and the Internet. He runs Ambient Sensors, a company focused on sensors and wireless sensor networks, and has a strong interest in the development of startup companies (and the scars to prove it). He especially enjoys sharing his interests and expertise with others.

Table of Contents

Preface vii

1 Introduction 1

What Makes BLE Different 1

The Specification 3

Configurations 3

Based on Specification Support 3

Based on Chip Count 5

Key Limitations 6

Data Throughput 6

Operating Range 8

Network Topology 9

Broadcasting and Observing 9

Connections 10

Protocols versus Profiles 12

Generic Profiles 13

Use-Case-Specific Profiles 13

2 Protocol Basics 15

Physical Layer 16

Link Layer 17

Bluetooth Device Address 19

Advertising and Scanning 19

Connections 22

Host Controller Interface (HCI) 24

Logical Link Control and Adaptation Protocol (L2CAP) 25

Attribute Protocol (ATT) 26

ATT operations 26

Security Manager (SM) 28

Security Procedures 29

Pairing Algorithms 30

Security Keys 31

Generic Attribute Profile (GATT) 32

Generic Access Profile (GAP) 33

5 GAP (Advertising and Connections) 35

Roles 36

Modo and Procedures 37

Broadcast and Observation 38

Discovery 39

Connection Establishment 41

Additional GAP Procedures 42

Security 43

Address Types 44

Authentication 45

Security Modes 45

Security Modes and Procedures 46

Additional GAP Definitions 48

Advertising Data Format 48

GAP Service 50

4 GATT (Services and Characteristics) 51

Roles 51

UUIDs 52

Attributes 53

Handle 53

Type 54

Permissions 54

Value 55

Attribute and Data Hierarchy 56

Services 58

Characteristics 59

Characteristic Descriptors 61

Example Service 63

Advanced Attribute Concepts 66

Attribute Caching 66

GATT Attribute Data in Advertising Packets 67

Features 68

Exchange MTU 68

Service and Characteristic Discovery 69

Reading Characteristics and Descriptors 70

Writing Characteristics and Descriptors 71

Server-Initiated Updates 72

Security 72

GATT Service 73

5 Hardware Platforms 75

nRF51822-EK (Nordic Semiconductors) 75

Technical Specifications 75

SoftDevice Architecture 76

Working with the nRF51822-EK 77

Examples and Toolchains 78

CC2541DK-MINI (Texas Instruments) 78

Other Hardware Platforms and Modules 80

Laird's BL600 Module 81

Bluegiga's BLE112/BLE113 Modules 81

RFDuino 82

6 Debugging Tools 83

PCA10000 USB Dongle and the Master Control Panel 83

PCA10000 USB Dongle and Wireshark 86

CC2540 USB Dongle and SmartRF Sniffer 88

SmartRF-to-Wireshark Converter 88

Bluez hcitool and galttool 89

7 Application Design Tools 91

Bluetooth Application Accelerator 91

SensorTag 91

LightBlue for iOS 93

nRF Master Control Panel for Android 94

8 Android Programming 97

Getting Started 97

Get the Hardware 97

Get the Software 98

Configure the Hardware 98

Start a New Project 101

Initializing the BLE Library 104

Connecting to a Remote Device 107

Communicating with a Remote Device 111

9 iOS Programming 123

Simple Battery-Level Peripheral 124

Scanning for Remote Peripherals 127

Connecting to Remote Peripherals 127

Looking Up Services Associated with a Remote Peripheral 128

Looking Up Characteristics Associated with Services 129

Methods for Reading and Decoding Characteristics 131

iBeacon 132

Advertising 133

Ranging 134

Implementing an iBeacon App 135

Apple Notification Center Service with an External Display 138

10 Embedded Application Development 143

mbed BLE API 144

Embedded Toolchains 145

Installing GNU Tools on OS X and Linux 146

Installing GNU Tools on Windows 148

nRF51822 GNU Codebase and Sample Project 149

Getting the nRF51822 GNU Codebase 150

nR51822 GNU Codebase Structure 150

Compiling Projects 152

Writing to the nRF51822 153

Going Further 156

Index 157