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  1. BUILD.gn
  2. OWNERS
  3. README.md
  4. bundles/
  5. core/
  6. docs/
  7. examples/
  8. fidl/
  9. hci/
  10. lib/
  11. profiles/
  12. testing/
  13. tests/
  14. tools/
src/connectivity/bluetooth/README.md

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:

For more orientation, see

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

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.x64 --with-base="//bundles:tools,//src/connectivity/bluetooth"

Tests

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. Look in the GN file of a production binary or library to find its associated unit tests.

Each test binary is a component whose runtime environment is defined by its .cmx component manifest

For example, bt-host-l2cap-tests is a Google Test binary that contains all the C++ L2CAP subsystem unit tests and is a standalone test package.

Running on a Fuchsia device
  • Run all the bt-host unit tests:

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

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

Running on QEMU

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

Integration Tests

See the Integration Test README

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.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

Profile Level Logging

Each Bluetooth profile has logging that can be turned on and can be useful during debugging. They're fully documented in the profile-specific README's here but there are a couple of examples below.

a2dp-sink=trace
a2dp-source=trace

bin/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. Add the --verbose option to the Bluetooth entries to increase verbosity, for example:

...
  "fuchsia.bluetooth.bredr.Profile":  "fuchsia-pkg://fuchsia.com/bt-init#meta/bt-init.cmx",
  "fuchsia.bluetooth.sys.Access": "fuchsia-pkg://fuchsia.com/bt-init#meta/bt-init.cmx",
  "fuchsia.bluetooth.gatt.Server":  "fuchsia-pkg://fuchsia.com/bt-init#meta/bt-init.cmx",
  "fuchsia.bluetooth.le.Central":  "fuchsia-pkg://fuchsia.com/bt-init#meta/bt-init.cmx",
  "fuchsia.bluetooth.le.Peripheral":  "fuchsia-pkg://fuchsia.com/bt-init#meta/bt-init.cmx",
  "fuchsia.bluetooth.snoop.Snoop":  "fuchsia-pkg://fuchsia.com/bt-snoop#meta/bt-snoop.cmx",
...

Inspecting Component State

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

Usage

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

The Bluetooth standard makes use of the terms “master” and “slave” to define link layer connection roles in many of the protocol specifications. Here are a few rules of thumb when referring to these roles in code and comments:

  1. Do not propagate these terms beyond the layer of code directly involved with link layer roles. Use the suggested alternative terminology at FIDL API boundaries. See Bluetooth Vocabulary Guide.

  2. Whenever possible, prefer different terms that more specifically describe function. For example, the SMP specification defines “initiator” and “responder” roles that correspond to the aforementioned roles without loss of clarity.

  3. If an explicit reference to the link layer role is necessary, then try to avoid the term “slave” where possible. For example this formulation avoids the term without losing clarity:

   if (link->role() != hci::Connection::Role::kMaster) {
     ...
   }

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