BLE States | Standby, Advertising, Scanning, Initiating, connection, Synchronization
This page describes BLE (Bluetooth Low Energy) states and BLE state diagram. The BLE states include Standby state, Advertising state, Scanning state, Initiating state, Connection State and Synchronization state.
BLE (Bluetooth Low Energy) is the standard defined by Bluetooth SIG. The link layer is the part or layer which directly interfaces to the PHYSICAL Layer. It is responsible for advertising, scanning, creating and maintaining of connections between Master and Slave devices.
The operation of BLE Link Layer can be described in terms of state diagram or machine as shown in the figure.
Let us understand these BLE states as follows.
• Link Layer State machine allows only one state to be active at a time.
• Link layer may have multiple instances of link layer state machine.
• It shall have at least one state machine which supports one of the advertising state or scanning state.
BLE States | BLE (Bluetooth Low Energy) State Diagram or machine
• Standby state: There is no transmission or reception of packet in this state. This state can be entered from any
other BLE states.
• Advertising state:A BLE device in this state is called "Advertiser". This state can be reached from "standby state". Link layer will transmit advertising packets and listens to and responds to responses triggered due to advertising packets.
• Scanning state: In this state, link layer listens for advertising packets from other advertising devices. The BLE device in this state is known as "scanner". This state can be reached from "standby state".
• Initiating state:The BLE device in this state is known as initiator. This BLE state can be reached from "standby state". Link layer listens for advertising physical packets from specific BLE devices. It also responds to these packets to initiate a connection from another device.
• Connection State: This state can be reached either from "initiating state" or "advertising state". In this connection state, there are two roles of BLE device either master or slave. When it has entered from "initiating state" it will be in master role. When it has entered from "advertising state" it will be in slave role. In master role, link layer will communicate with device in the slave role and defines timings of transmissions.
• Synchronization state: This state can be entered from "standby state". The link layer in this state listens for periodic channel packets from specified device transmitting periodic advertising.
➤BLUETOOTH CORE SPECIFICATION Version 5.1
Previous versions of Bluetooth 5.0 or Bluetooth Low Energy (BLE) Related Links
Also refer bluetooth tutorial covering following sub topics:
Main Page Frequency PHY Layer MAC layer Stack Power classes Security products Bluetooth Vs BLE Bluetooth vs zigbee Bluetooth Vs WiFi vs NFC vs RFID Difference between Bluetooth Versions
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