firemaples / BluetoothRFCOMMTest

Android Bluetooth RFCOMM client

Pairing with CompanionDeviceManager

Documents

Companion device pairing

Requirements

• Devices running Android 8.0 (API level 26) and higher
• Enabling bluetooth before use CompanionDeviceManager

Permissions

<!-- For requesting enabling bluetooth -->
<uses-permission android:name="android.permission.BLUETOOTH" />

<!-- For companion device pairing -->
<uses-feature android:name="android.software.companion_device_setup" />

<!-- To start the app from the background -->
<uses-permission android:name="android.permission.REQUEST_COMPANION_RUN_IN_BACKGROUND" />
<uses-permission android:name="android.permission.REQUEST_COMPANION_USE_DATA_IN_BACKGROUND" />

How it works

• You have ever paired/is pairing the target device while the RFCOMM server was/is opening before (there's a local cache for companion devices).

1. Find the companion device by calling CompanionDeviceManager#associate() with one or more following attributes.
   • A MAC address.
   • A regex for matching the name.
   • A service UUID with or without a bits mask.
2. The Android system pops up a dialog to comfirm the action.

3. **(If the companion device is not paired now)** The Android system shows up a dialog to pair the device.

4. Connect to the received **BluetoothDevice**.

Discoverying by trandictonal BT APIs

Documents

Bluetooth overview

Requirements

Permissions

<!-- For requesting enabling bluetooth -->
<uses-permission android:name="android.permission.BLUETOOTH" />

<!-- For discovery BT devices -->
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />

How it works

• The BluetoothAdapter can only execute one task at a time.
• You can select the bluetooth devcie by name, MAC address or UUIDs.
• The UUIDs is not always available from the discovery task or the UUIDs fetching task.
• Pairing the target device before the following steps is a more stable way to find the device you want.

1. Get then check the bounded devices by BluetoothAdapter#getBoudedDevices().
2. If there's a device that matches the UUID then connect it. Otherwise start the bluetooth discovery to find other devices by BluetoothAdapter#startDiscovery().
3. At this time, you will receive bluetooth devices by broadcast BluetoothDevice.ACTION_FOUND, if anyone contains the UUID, cancel the discovery and connect the bluetooth device.
4. After the discovery finished (receiving the broadcast BluetoothAdapter.ACTION_DISCOVERY_FINISHED), if none of the discovered devices matches the UUID, fetch the UUIDs of all dicovered devices one by one with BluetoothDevice#fetchUuidsWithSdp().
5. If any device's UUID from broadcast BluetoothDevice.ACTION_UUID that matches the UUID, stop the UUID fetching task and connect the matched device.