Bluetooth profiles

The Bluetooth API includes support for working with Bluetooth profiles. A Bluetooth profile is a wireless interface specification for Bluetooth-based communication between devices, such as the Hands-Free profile. For a mobile device to connect to a wireless headset, both devices must support the Hands-Free profile.

The Bluetooth API provides implementations for the following Bluetooth profiles:

Headset. The Headset profile provides support for Bluetooth headsets to be used with mobile phones. Android provides the BluetoothHeadset class, which is a proxy for controlling the Bluetooth Headset Service. This includes both Bluetooth Headset and Hands-Free (v1.5) profiles. The BluetoothHeadset class includes support for AT commands. For more on this topic, see Vendor-specific AT commands.
A2DP. The Advanced Audio Distribution Profile (A2DP) profile defines how high-quality audio can be streamed from one device to another over a Bluetooth connection. Android provides the BluetoothA2dp class, which is a proxy for controlling the Bluetooth A2DP Service.
Health Device. Android provides support for the Bluetooth Health Device Profile (HDP). This lets you create apps that use Bluetooth to communicate with health devices that support Bluetooth, such as heart-rate monitors, blood meters, thermometers, scales, and so on. For a list of supported devices and their corresponding device data specialization codes, see Bluetooth's HDP Device Data Specializations. These values are also referenced in the ISO/IEEE 11073-20601 [7] specification as MDC_DEV_SPEC_PROFILE_* in the Nomenclature Codes Annex. For more information about HDP, see Health Device Profile.

Here are the basic steps for working with a profile:

Get the default adapter, as described in Bluetooth setup.
Set up a BluetoothProfile.ServiceListener. This listener notifies BluetoothProfile clients when they have been connected to or disconnected from the service.
Use getProfileProxy() to establish a connection to the profile proxy object associated with the profile. In the following example, the profile proxy object is an instance of BluetoothHeadset.
In onServiceConnected(), get a handle to the profile proxy object.
Once you have the profile proxy object, use it to monitor the state of the connection and perform other operations that are relevant to that profile.

The following code snippet shows how to connect to a BluetoothHeadset proxy object so that you can control the Headset profile:

Kotlin

var bluetoothHeadset: BluetoothHeadset? = null

// Get the default adapter
val bluetoothAdapter: BluetoothAdapter? = BluetoothAdapter.getDefaultAdapter()

private val profileListener = object : BluetoothProfile.ServiceListener {

    override fun onServiceConnected(profile: Int, proxy: BluetoothProfile) {
        if (profile == BluetoothProfile.HEADSET) {
            bluetoothHeadset = proxy as BluetoothHeadset
        }
    }

    override fun onServiceDisconnected(profile: Int) {
        if (profile == BluetoothProfile.HEADSET) {
            bluetoothHeadset = null
        }
    }
}

// Establish connection to the proxy.
bluetoothAdapter?.getProfileProxy(context, profileListener, BluetoothProfile.HEADSET)

// ... call functions on bluetoothHeadset

// Close proxy connection after use.
bluetoothAdapter?.closeProfileProxy(BluetoothProfile.HEADSET, bluetoothHeadset)

Java

BluetoothHeadset bluetoothHeadset;

// Get the default adapter
BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

private BluetoothProfile.ServiceListener profileListener = new BluetoothProfile.ServiceListener() {
    public void onServiceConnected(int profile, BluetoothProfile proxy) {
        if (profile == BluetoothProfile.HEADSET) {
            bluetoothHeadset = (BluetoothHeadset) proxy;
        }
    }
    public void onServiceDisconnected(int profile) {
        if (profile == BluetoothProfile.HEADSET) {
            bluetoothHeadset = null;
        }
    }
};

// Establish connection to the proxy.
bluetoothAdapter.getProfileProxy(context, profileListener, BluetoothProfile.HEADSET);

// ... call functions on bluetoothHeadset

// Close proxy connection after use.
bluetoothAdapter.closeProfileProxy(bluetoothHeadset);

Vendor-specific AT commands

Apps can register to receive system broadcasts of predefined vendor-specific AT commands sent by headsets (such as a Plantronics +XEVENT command). For example, an app could receive broadcasts that indicate a connected device's battery level and could notify the user or take other action as needed. Create a broadcast receiver for the ACTION_VENDOR_SPECIFIC_HEADSET_EVENT intent to handle vendor-specific AT commands for the headset.

Health Device Profile

Android supports the Bluetooth Health Device Profile (HDP). The Bluetooth Health API includes the classes BluetoothHealth, BluetoothHealthCallback, and BluetoothHealthAppConfiguration, which are described in Key classes and interfaces.

When using the Bluetooth Health API, it's helpful to understand these key HDP concepts:

Source: A health device, such as a weight scale, glucose meter, or thermometer, which transmits medical data to a smart device, such as an Android phone or tablet.
Sink: The smart device that receives the medical data. In an HDP app, the sink is represented by a BluetoothHealthAppConfiguration object.
Registration: The process used to register a sink for communicating with a particular health device.
Connection: The process used to open a channel between a health device (source) and a smart device (sink).

Create an HDP app

Here are the basic steps involved in creating an HDP app:

Get a reference to the BluetoothHealth proxy object. As with regular headset and A2DP profile devices, you must call getProfileProxy() with a BluetoothProfile.ServiceListener and the HEALTH profile type to establish a connection with the profile proxy object.
Create a BluetoothHealthCallback and register an app configuration (BluetoothHealthAppConfiguration) that acts as a health sink.
Establish a connection to a health device.

Note: Some devices initiate the connection automatically. It is unnecessary to carry out this step for those devices.
When connected successfully to a health device, read and write to the health device using the file descriptor. The received data needs to be interpreted using a health manager, which implements the IEEE 11073 specifications.
When done, close the health channel and unregister the app. The channel also closes when there is extended inactivity.