• 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 sendsadvertising packets with data
• Uses the Link LayerAdvertiser role

Observer

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

Network Topology

Peripheral/Central

This role pair implements bidirectional, connection-oriented communications.

Peripheral

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

Central

• Link LayerMaster role
• Capable of establishing and managing aconnection
• May be connected to various devices simultaneously

Network Topology

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

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