AN91267 Datasheet, PDF (52/62 Pages) Ramtron International Corporation – Getting Started with PSoC

Getting Started with PSoC® 4 BLE
Appendix E: BLE Protocol
Overview
BLE, also known as Bluetooth Smart, was introduced by the Bluetooth SIG as a low-power wireless standard
operating in the 2.4-GHz ISM band. Figure 61 shows the BLE stack.
Figure 61. BLE Architecture
Applications
Generic Access Profile (GAP)
Generic Attribute Profile (GATT)
Attribute Protocol (ATT) Security Manager (SM)
Host
Logical Link Control and Adaption Protocol (L2CAP)
Host Control Interface (HCI)
Link Layer (LL)
Physical Layer (PHY)
Controller
The BLE stack can be subdivided into three groups:
 Controller: A physical device that encodes the packet and transmits it as radio signals. On reception, the
controller decodes the radio signals and reconstructs the packet.
 Host: A software stack consisting of various protocols and Profiles (Security Manager, Attribute Protocol, and so
on) that manages how two or more devices communicate with one another.
 ^{Application: A use case that uses the software stack and the controller to implement a particular functionality.}
The following sections provide an overview of the multiple layers of the BLE stack, using the standard Heart Rate and
Battery Service as examples. For a detailed BLE architecture description, see the Bluetooth 4.1 specification or the
training videos on the Bluetooth Developer website.
Physical Layer (PHY)
The physical layer transmits or receives digital data at 1 Mbps using Gaussian frequency-shift keying (GFSK)
modulation in the 2.4-GHz ISM band. The BLE physical layer divides the ISM band into 40 RF channels with a
channel spacing of 2 MHz, 37 of which are data channels and 3 are advertisement channels.
Link Layer (LL)
The link layer implements key procedures to establish a reliable physical link (using an acknowledgement and flow-
control-based architecture) and features that help make the BLE protocol robust and low power. Some link layer
functions include:
 ^{Advertising, scanning, creating, and maintaining connections to establish a physical link}
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