Generic Access Profile (GAP) Roles

Overview

Bluetooth^® Low Energy (BLE) devices can operate in one or more Generic Access Profile (GAP) roles at the same time (provided the Link Layer supports this):

• Broadcaster
• Observer
• Peripheral
• Central

The role imposes restrictions and enforces behavior, so it is generally fixed in the design stage of the device.

Two role pairs are defined, allowing devices to communicate with each other.

Broadcaster/Observer

This role pair implements unidirectional, connection-less communications.

Broadcaster

• Periodically sends advertising packets with data
• Uses the Link Layer Advertiser role

Observer

• Scans for broadcasters, listening for advertising data
• Uses the Link Layer Scanner role

Network Topology

Peripheral/Central

This role pair implements bidirectional, connection-oriented communications.

Peripheral

• Link Layer Slave role
• Advertises by using connectable advertising packets
• Optimized to consume the least amount of processing power and memory
  • Enables a low-cost design
    

Central

• Link Layer Master role
• Capable of establishing and managing a connection
• May be connected to various devices simultaneously

Network Topology

For data transfer operations in BLE connections, different roles are defined by the Generic Attribute Profile layer.