Bluetooth

The Fuchsia Bluetooth system aims to provide a dual mode implementation of the Bluetooth Host Subsystem (5.0+) supporting a framework for developing Low Energy and Traditional profiles.

Source code shortcuts:

• Public API:
  • Shared
  • System API
  • BR/EDR (Profile)
  • GATT
  • LE
• Private API
• Tools
• Host Subsystem Driver
• HCI Drivers
• HCI Transport Drivers

For more orientation, see

• System Architecture
• Respectful Code

For a note on used (and avoided) vocabulary, see Bluetooth Vocabulary

Getting Started

API Examples

Examples using Fuchsia's Bluetooth Low Energy APIs can be found here.

Privileged System API

Dual-mode (LE + Classic) GAP operations that are typically exposed to privileged clients are performed using the fuchsia.bluetooth.sys library. This API is intended for managing local adapters, device discovery & discoverability, pairing/bonding, and other settings.

bt-cli is a command-line front-end for privileged access operations:

$ bt-cli
bt> list-adapters
Adapter:
    Identifier:     e5878e9f642d8908
    Address:        34:13:E8:86:8C:19
    Technology:     DualMode
    Local Name:     siren-relic-wad-pout
    Discoverable:   false
    Discovering:    false
    Local UUIDs:    None

Tools

See the bluetooth/tools package for more information on available command line tools for testing/debugging.

Running Tests

Your build configuration may or may not include Bluetooth tests. Ensure Bluetooth tests are built and installed when paving or OTA'ing with fx set:

  $ fx set workstation_eng.x64 --with //src/connectivity/bluetooth,//bundles/tools

Tests

The Bluetooth codebase follows the Fuchsia testing best practices. In general, the Bluetooth codebase defines an associated unit test binary for each production binary and library, as well as a number of integration test binaries. Without good reason, no code should be added without an appropriate (unit, integration, etc) corresponding test. Look in the GN file of a production binary or library to find its associated unit tests.

For more information, see the Fuchsia testing guide.

Running on a Fuchsia device

• Run all the bt-host unit tests:

  $ fx test //src/connectivity/bluetooth/core/bt-host
  

• Run a specific test within bt-host:

  $ fx test //src/connectivity/bluetooth/core/bt-host -- --gtest_filter='Foo.Bar'
  

  Where Foo and Bar in Foo.Bar are the fixture name and the test name, respectively.

To see all options for running these tests, run fx test --help.

Running on the Fuchsia Emulator

If you don't have physical hardware available, you can run the tests in the Fuchsia emulator (FEMU) using the same commands as above. See FEMU set up instructions.

Integration Tests

See the Integration Test README. TODO(fxbug.dev/96421): This link is very outdated, rewrite and update.

Controlling Log Verbosity

Logging in Drivers

The most reliable way to enable higher log verbosity is with kernel command line parameters. These can be configured through the fx set command:

  fx set workstation_eng.x64 --args="dev_bootfs_labels=[\"//src/connectivity/bluetooth:driver-debug-logging\"]"

This will enable debug-level logging for all supported chipsets. Using fx set writes these values into the image, so they will survive a restart. For more detail on driver logging, see Zircon driver logging

core/bt-gap

The Bluetooth system service is invoked by sysmgr to resolve service requests. The mapping between environment service names and their handlers is defined in //src/sys/sysmgr/config/services.config.

Inspecting Component State

The Bluetooth system supports inspection through the Inspect API. bt-gap, bt-host, bt-a2dp, and bt-snoop all expose information though Inspect.

Usage

• bt-host: ffx inspect show bootstrap/driver_manager --file class/bt-host/000.inspect exposes information about the controller, peers, and services.
• bt-gap: ffx inspect show core/bluetooth-core/bt-gap exposes information on host devices managed by bt-gap, pairing capabilities, stored bonds, and actively connected peers.
• bt-a2dp: ffx inspect show core/bt-a2dp exposes information on audio streaming capabilities and active streams
• bt-snoop: ffx inspect show core/bt-snoop exposes information about which hci devices are being logged and how much data is stored.
• All core Bluetooth components ffx inspect show core/bluetooth-core/*
• All other Bluetooth components: ffx inspect show core/bt-*

See the iquery documentation for complete instructions on using iquery.

Respectful Code

Inclusivity is central to Fuchsia's culture, and our values include treating each other with dignity. As such, it’s important that everyone can contribute without facing the harmful effects of bias and discrimination.

Bluetooth Core Specification 5.3 updated certain terms that were identified as inappropriate to more inclusive versions. For example, usages of ‘master’ and ‘slave’ were changed to ‘central’ and ‘peripheral’, respectively. We have transitioned our code's terminology to the more appropriate language. We no longer allow uses of the prior terms. For more information, see the Appropriate Language Mapping Table published by the Bluetooth SIG.

See the Fuchsia project guide on best practices for more information.