Hardware Reference
In-Depth Information
CHAPTER 2
Protocol Basics
Although users will usually interface directly only with the upper layers of the Bluetooth
Low Energy protocol stack, it's probably best to begin with a basic overview of the
complete stack, which provides a solid foundation to understanding how and why things
operate the way they do.
As shown in
Figure 2-1
, a complete single-mode BLE device is divided into three parts:
controller, host, and application.
Each of these basic building blocks of the protocol stack is split into several layers that
provide the functionality required to operate:
Application
The application, like in all other types of systems, is the highest layer and the one
responsible for containing the logic, user interface, and data handling of everything
related to the actual use-case that the application implements. The architecture of
an application is highly dependent on each particular implementation.
Host
Includes the following layers:
• Generic Access Profile (GAP)
• Generic Attribute Profile (GATT)
• Logical Link Control and Adaptation Protocol (L2CAP)
• Attribute Protocol (ATT)
• Security Manager (SM)
• Host Controller Interface (HCI), Host side
Controller
Includes the following layers:
