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<html devsite>
<head>
<title>IVI Connectivity</title>
<meta name="project_path" value="/_project.yaml" />
<meta name="book_path" value="/_book.yaml" />
</head>
<body>
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<p>
Android 8.0 creates a more seamless Bluetooth user experience
when connecting devices to the in-vehicle infotainment system (IVI).
The IVI listens for events, such as unlocking a car door
or starting the engine, and automatically scans for in-range
Bluetooth devices. It will also simultaneously connect to separate
devices so users can make hands-free calls on any device.
</p>
<h2 id="bluetooth-connection-management">Bluetooth connection management</h2>
<p>
In Android 7.x and earlier, the IVI Bluetooth stack
scans for devices only when the Bluetooth adapter is powered on. Users have to
connect manually if their device comes into range while the IVI Bluetooth is on.
Android 8.0 reduces the need for users to manually connect their devices through
the IVI settings app.
</p>
<p>
While the Bluetooth adapter is on and not connected to a device, customizable
trigger events (such as unlocking the door or starting the engine) cause the
IVI Bluetooth to scan for in-range devices to pair with on available profiles.
The IVI Bluetooth then uses a priority list to determine which device to
connect with.
</p>
<p>
In addition to the trigger events, you can specify the device priority for each
profile. In the default implementation, the IVI Bluetooth prioritizes the most
recently connected device. There is a separate priority list for each Bluetooth
service, so each service profile can be connected to a different device. Each
Bluetooth service profile also has a different connection limit.
</p>
<table>
<tr>
<th>Service</th>
<th>Profile</th>
<th>Connection limit</th>
</tr>
<tr>
<td rowspan="2">Phone</td>
<td>HFP</td>
<td>2</td>
</tr>
<tr>
<td>PBAP</td>
<td>2</td>
</tr>
<tr>
<td>Message</td>
<td>MAP</td>
<td>1</td>
</tr>
<tr>
<td>Audio</td>
<td>A2DP</td>
<td>1</td>
</tr>
</table>
<h3 id="implement-connection-management">Implement connection management</h3>
<p>
To support auto-connect in Android 8.0, the Bluetooth connection management logic
moved from the Bluetooth Service to a policy in Car Service. Within a policy,
you can customize when the Bluetooth auto-connect should scan for new devices,
and which devices it should attempt to connect to first.
</p>
<p>
The default connection policy can be found in <code><a
href="https://android.googlesource.com/platform/packages/services/Car/+/oreo-r6-release/service/src/com/android/car/BluetoothDeviceConnectionPolicy.java">
service/src/com/android/car/BluetoothDeviceConnectionPolicy.java</a></code>.
To use a custom phone policy, disable the default phone policy in <code><a href="https://android.googlesource.com/platform/packages/apps/Bluetooth/+/master/res/values/config.xml">
res/values/config.xml</a></code> by setting <code>enable_phone_policy</code>
to <code>false</code>.
</p>
<p>
To create a trigger event, register a listener to the respective Car Service.
Example of a new sensor event:
</p>
<pre class="prettyprint">
/**
* Handles events coming in from the {@link CarSensorService}
* Upon receiving the event that is of interest, initiate a connection attempt by
* calling the policy {@link BluetoothDeviceConnectionPolicy}
*/
private class CarSensorEventListener extends ICarSensorEventListener.Stub {
@Override
public void onSensorChanged(List<CarSensorEvent> events) throws RemoteException {
if (events != null & !events.isEmpty()) {
CarSensorEvent event = events.get(0);
if (event.sensorType == CarSensorManager.SOME_NEW_SENSOR_EVENT) {
initiateConnection();
}
...
}
</pre>
<p>
To configure the device priority for each profile, modify the following methods
in <code><a
href="https://android.googlesource.com/platform/packages/services/Car/+/oreo-r6-release/service/src/com/android/car/BluetoothDeviceConnectionPolicy.java">
BluetoothDeviceConnectionPolicy</a></code>:
</p>
<ul>
<li><code>updateDeviceConnectionStatus()</code></li>
<li><code>findDeviceToConnect()</code></li>
</ul>
<h3 id="verify-connection-management">Verify connection management</h3>
<p>
Verify the behavior of the Bluetooth connection management by toggling Bluetooth
on your Android Automotive IVI and see that it automatically connects to the
appropriate devices.
</p>
<p>
You can use the following <code>adb</code> commands to test your IVI with
simulated vehicle events:
</p>
<ul>
<li>For <code>CarCabinManager.ID_DOOR_LOCK</code>:
<pre class="devsite-terminal devsite-click-to-copy">adb shell dumpsys activity service com.android.car inject-event zoned-boolean 0x16200b02 1 false</pre>
</li>
<li>For <code>CarSensorManager.SENSOR_TYPE_IGNITION_STATE</code>:
<pre class="devsite-terminal devsite-click-to-copy">adb shell dumpsys activity service com.android.car inject-event global-integer 0x11400409 5</pre>
</li>
</ul>
<h2 id="bluetooth-multi-device-connectivity">Bluetooth multi-device connectivity</h2>
<p>
In Android 8.0, the IVI can support multiple devices connected simultaneously
over Bluetooth. Multi-device Bluetooth phone services let users connect
separate devices, such as a personal phone and a work phone, and make
hands-free calls from either device. This feature increases driving safety by
reducing distraction and improves in-call experiences by taking advantage
of automotive audio systems.
</p>
<h3 id="multi-device-connectivity">Multi-device connectivity</h3>
<p>
When a trigger event happens, the <a
href="https://android.googlesource.com/platform/packages/services/Car/+/oreo-r6-release/service/src/com/android/car/BluetoothDeviceConnectionPolicy.java">
Bluetooth Connection Management Policy</a> determines which devices to connect
to on each Bluetooth profile. The policy then sends a connect intent to the
profile client service. In turn, the profile client service creates a client
state machine instance to manage the connection with each device.
</p>
<h4 id="hands-free-profile">Hands-Free Profile</h4>
<p>
The Bluetooth Hands-Free Profile (HFP) in Android 8.0 lets two devices connect
concurrently, and either device can make or receive phone calls. To do this,
each connection registers a separate phone account with the Telecom Manager,
which advertises the phone accounts to the IVI apps.
</p>
<p>
When a user makes or receives a phone call from a device, the corresponding
phone account creates an <code>HfpClientConnection</code> object. The Dialer app
interacts with the <code>HfpClientConnection</code> object to manage call
features, such as accepting a call or hanging up. However, the Dialer app does
not indicate which device an incoming call is coming from. To make an outgoing
call, the app uses the last connected device. Manufacturers can change this
behavior by customizing the Dialer app.
</p>
<h4 id="phone-book-access-profile">Phone Book Access Profile</h4>
<p>
The Bluetooth Phone Book Access Profile (PBAP) downloads contacts
from all connected devices. PBAP maintains an aggregated, searchable list of
contacts that is updated by PBAP client state machines. Because each device
interacts with a separate PBAP client state machine, contacts are associated
with the proper device when making a call. When a PBAP client disconnects, the
internal database removes all contacts associated with that phone.
</p>
<h3 id="implement-multi-device-hfp">Implement multi-device HFP</h3>
<p>
Using the default Android Bluetooth stack, an IVI automatically has the ability
to connect to multiple devices on HFP. The <code>MAX_STATE_MACHINES_POSSIBLE</code>
in the <code><a href="https://android.googlesource.com/platform/packages/apps/Bluetooth/+/master/src/com/android/bluetooth/hfpclient/HeadsetClientService.java">
HeadsetClientService</a></code> defines the maximum number of simultaneous
HFP connections.
</p>
<aside class="note"><strong>Note:</strong> HFP Synchronous Connection
Oriented (SCO) connections and phone call
audio routing need to be done manually with <code><a
href="https://android.googlesource.com/platform/system/bt/+/master/binder/android/bluetooth/IBluetoothHeadsetClient.aidl">
connectAudio</a></code> in the application Binder.
</aside>
<p>
When implementing multi-device HFP, you should customize your Dialer app UI to
let users select which device account to use when making a call. The app then
calls <code>telecomManager.placeCall</code> with the correct account.
</p>
<h3 id="verify-multi-device-hfp">Verify multi-device HFP</h3>
<p>
To check that multi-device connectivity works properly over Bluetooth:
</p>
<ol>
<li>Using Bluetooth, connect a device to the IVI and stream audio from the
device.</li>
<li>Connect two phones to the IVI over Bluetooth.</li>
<li>Pick one phone. Place an outgoing call directly from the phone,
and place an outgoing call using the IVI.
<ol>
<li>Both times, verify the streamed audio pauses and the phone audio
plays over the IVI connected speakers.</li>
</ol>
</li>
<li>Using the same phone, receive an incoming call directly on the phone, and
receive an incoming call using the IVI.
<ol>
<li>Both times, verify the stream audio pauses and the
phone audio plays over the IVI connected speakers.</li>
</ol>
</li>
<li>Repeat steps 3 and 4 with the other connected phone.</li>
</ol>
<aside class="note"><strong>Note</strong>: The Bluetooth PBAP profile,
like the MAP profile, is unidirectional. To connect a device on these profiles,
the connection needs to be instantiated from the IVI and not the source device.
</aside>
</body>
</html>
|
