A radical new departure from conventional Bluetooth technology, Bluetooth Low Energy (BLE) will enable a whole new generation of wireless applications in industries ranging from healthcare to transportation. Running on a single coin-sized battery, BLE can run for years, connecting and extending everything from Personal Area Network devices to next-generation sensors. In Bluetooth Low Energy, one of the standard's developers has written the first comprehensive, accessible introduction to BLE for every system developer, designer, and engineer. Robin Heydon, a member of the Bluetooth "Hall of Fame" brings together information currently scattered through multiple standards documents, offering the context and leading-edge implementation insights needed to build high-performance working systems with BLE. Heydon begins by reviewing BLE's design goals, explaining how they drove key architectural decisions, and introducing BLE's innovative usage models. Next, he thoroughly covers the Controller side of the standard, offering detailed information on physical and link layers, direct test mode, and the host controller interface. Finally, he turns to BLE hosts, explaining L2CAP, attributes, BLE security, and the Generic Access Profile. This book will be an indispensable companion to the official BLE standards documents for every technical professional and decision-maker who is considering BLE, planning BLE products, or transforming plans into working systems.