Fuchsia Connectivity Bluetooth

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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
    • BR/EDR
    • Control
    • GATT
    • LE
  • Private API
  • Tools
  • Host Bus Driver
  • HCI Drivers
  • HCI Transport Drivers

For more orientation, see

  • System Architecture
  • Detailed Source Layout

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.

Control API

Dual-mode (LE + Classic) GAP operations that are typically exposed to privileged
clients are performed using the control.fidl
API. 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 this API:

$ bt-cli
bluetooth> list-adapters
  Adapter 0
    id: bf004a8b-d691-4298-8c79-130b83e047a1
    address: 00:1A:7D:DA:0A
bluetooth>

We also have a Flutter module
that acts as a Bluetooth system menu based on this API at
topaz/bin/bluetooth_settings.

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

Bluetooth test packages are listed in
tests/bluetooth and each contains at least one
test binary. Refer to package definitions for each package’s binaries.

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

For example, bt-host-unittests is a Google Test
binary that contains all the C++ bt-host subsystem unit tests and is a part of
the bluetooth-tests package.

Running on a Fuchsia device

  • Run all the bt-host unit tests from the target shell:

    $ run-test-component bt-host-unittests

  • Or use the --gtest_filter
    flag to run a subset of the tests:

    # This only runs the L2CAP unit tests.
$ run-test-component bt-host-unittests --gtest_filter=L2CAP_\*

  • And use the --verbose flag to set log verbosity:

    # This logs all messages logged using FXL_VLOG up to level 2 (equivalent to ::bt::common::LogSeverity:SPEW)
$ run-test-component bt-host-unittests --verbose=2

  • After making library or test changes, you can push the test package and run it
    from your development shell:

    $ fx run-test bluetooth-tests -t bt-host-unittests -- --gtest_filter=L2CAP_\*

Note the use of the package name bluetooth-tests and the extra -- used to
separate arguments passed to the test binary.

See Developing with Fuchsia packages
for more details on the package-based workflow.

Running on QEMU

If you don’t have physical hardware available, you can run the tests in QEMU using the same commands as above. A couple of tips will help run the tests a little more quickly.

  • Run the VM with hardware virtualization support: fx run -k

  • Disable unnecessary logging for the tests:

    $ run-test-component bt-host-unittests --quiet=10

With these two tips, the full bt-host-unittests suite runs in ~2 seconds.

Integration Tests

See the Integration Test README

Controlling Log Verbosity

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="kernel_cmdline_files=[\"//local/kernel_cmdline.txt\"]"

Add the commands to $FUCHSIA_DIR/local/kernel_cmdline.txt, e.g. to enable full logging for the USB transport, Intel HCI, and host drivers:

$ cat $FUCHSIA_DIR/local/kernel_cmdline.txt
driver.bt_host.log=+trace,+spew,+info,+error,+warn
driver.bt_hci_intel.log=+trace,+spew,+info,+error,+warn
driver.bt_transport_usb.log=+trace,+info,+error,+warn

(HCI drivers other than Intel can also be set. Other hci drivers include bt_hci_atheros, bt_hci_passthrough, and bt_hci_emulator)

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

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
//garnet/bin/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.control.Control": "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",
...