Bluetooth

Zephyr comes integrated with a feature-rich and highly configurable Bluetooth stack:

  • Bluetooth 5.0 compliant (ESR10)
  • Bluetooth Low Energy Controller support (LE Link Layer)
    • BLE 5.0 compliant
    • Unlimited role and connection count, all roles supported
    • Concurrent multi-protocol support ready
    • Intelligent scheduling of roles to minimize overlap
    • Portable design to any open BLE radio, currently supports Nordic Semiconductor nRF51 and nRF52
  • Generic Access Profile (GAP) with all possible LE roles
    • Peripheral & Central
    • Observer & Broadcaster
  • GATT (Generic Attribute Profile)
    • Server (to be a sensor)
    • Client (to connect to sensors)
  • Pairing support, including the Secure Connections feature from Bluetooth 4.2
  • Bluetooth Mesh support
    • Relay, Friend Node, Low-Power Node (LPN) and GATT Proxy features
    • Both Provisioning bearers supported (PB-ADV & PB-GATT)
    • Highly configurable, fits as small as 16k RAM devices
  • IPSP/6LoWPAN for IPv6 connectivity over Bluetooth LE
    • IPSP node sample application in samples/bluetooth/ipsp
  • Basic Bluetooth BR/EDR (Classic) support
    • Generic Access Profile (GAP)
    • Logical Link Control and Adaptation Protocol (L2CAP)
    • Serial Port emulation (RFCOMM protocol)
    • Service Discovery Protocol (SDP)
  • Clean HCI driver abstraction
    • 3-Wire (H:5) & 5-Wire (H:4) UART
    • SPI
    • Local controller support as a virtual HCI driver
  • Raw HCI interface to run Zephyr as a Controller instead of a full Host stack
    • Possible to export HCI over a physical transport
    • samples/bluetooth/hci_uart sample for HCI over UART
    • samples/bluetooth/hci_usb sample for HCI over USB
  • Verified with multiple popular controllers
  • Highly configurable
    • Features, buffer sizes/counts, stack sizes, etc.

Source tree layout

The stack is split up as follows in the source tree:

subsys/bluetooth/host
The host stack. This is where the HCI command & event handling as well as connection tracking happens. The implementation of the core protocols such as L2CAP, ATT & SMP is also here.
subsys/bluetooth/controller
Bluetooth Controller implementation. Implements the controller-side of HCI, the Link Layer as well as access to the radio transceiver.
include/bluetooth/
Public API header files. These are the header files applications need to include in order to use Bluetooth functionality.
drivers/bluetooth/
HCI transport drivers. Every HCI transport needs its own driver. E.g. the two common types of UART transport protocols (3-Wire & 5-Wire) have their own drivers.
samples/bluetooth/
Sample Bluetooth code. This is a good reference to get started with Bluetooth application development.
tests/bluetooth/
Test applications. These applications are used to verify the functionality of the Bluetooth stack, but are not necessary the best source for sample code (see samples/bluetooth instead).
doc/subsystems/bluetooth/
Extra documentation, such as PICS documents.

Further reading

More information on the stack and its usage can be found here and in the following subsections: