.. _bluetooth:

Bluetooth Implementation
########################

Initialization
**************

Initialize the Bluetooth subsystem using :c:func:`bt_init()`. Caller shall
be either task or a fiber. Caller must ensure that function succeeds by
checking return code for errors.

APIs
****

The following Bluetooth APIs are provided:

:c:func:`bt_enable()`
   Enables the Bluetooth subsystem.

:c:func:`bt_le_adv_start()`
   Sets up advertisement, scans for data, and starts advertising.

.. todo:: Describe all API

Bluetooth Application Example
*****************************

A simple Bluetooth beacon application is shown below. The application
initializes a Bluetooth Subsystem and enables non-connectable advertising.
It acts as a Bluetooth Low Energy broadcaster.

.. literalinclude:: ../../../samples/bluetooth/beacon/src/main.c
   :language: c
   :lines: 19-
   :linenos:

Testing with QEMU
*****************

A Bluetooth application might be tested with QEMU. In order to do so,
a Bluetooth controller needs to be connected to the emulator.

Using Host System Bluetooth Controller in QEMU
==============================================

The host system's Bluetooth controller is connected to the second QEMU
serial line using a UNIX socket. This socket employs the QEMU option
:literal:`-serial unix:/tmp/bt-server-bredr`. This option is already
added to QEMU through :makevar:`QEMU_EXTRA_FLAGS` in the Makefile.

On the Host side, BlueZ allows to "connect" Bluetooth controller through
a so-called user channel.

#. Use the btproxy tool to open the listening UNIX socket, type:

    .. code-block:: console

        $ sudo tools/btproxy -u
        Listening on /tmp/bt-server-bredr

    .. note:: Ensure that the Bluetooth controller is down before using the
              btproxy command.


#. To run Bluetooth application in the QEMU, go to application folder and type:

    .. code-block:: console

        $ make qemu

    .. note:: Bluetooth sample applications are located in
              :literal:`samples/bluetooth` folder.

Running QEMU now results in a connection with the second serial line to
:literal:`bt-server-bredr` UNIX socket.
Now, an application can use the Bluetooth device.