How to pair Bluetooth device programmatically Android

Question

I am developing an application where I want to connect a Bluetooth device main issue is I don\'t want user to enter required pin instead application should do that by himsel

Answer 1

Try this code:

public void pairDevice(BluetoothDevice device)
{
    String ACTION_PAIRING_REQUEST = "android.bluetooth.device.action.PAIRING_REQUEST";
    Intent intent = new Intent(ACTION_PAIRING_REQUEST);
    String EXTRA_DEVICE = "android.bluetooth.device.extra.DEVICE";
    intent.putExtra(EXTRA_DEVICE, device);
    String EXTRA_PAIRING_VARIANT = "android.bluetooth.device.extra.PAIRING_VARIANT";
    int PAIRING_VARIANT_PIN = 0;
    intent.putExtra(EXTRA_PAIRING_VARIANT, PAIRING_VARIANT_PIN);
    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    context.startActivity(intent);
}

Intent intent = new Intent(BluetoothDevice.ACTION_PAIRING_REQUEST);
intent.putExtra(EXTRA_DEVICE, device);
int PAIRING_VARIANT_PIN = 272;
intent.putExtra(BluetoothDevice.EXTRA_PAIRING_VARIANT, PAIRING_VARIANT_PIN);
sendBroadcast(intent);

Intent intent = new Intent(Settings.ACTION_BLUETOOTH_SETTINGS);
startActivityForResult(intent, REQUEST_PAIR_DEVICE);

I hope this helps

Reference: http://pastebin.com/N8dR4Aa1

Answer 2

Register a BluetoothDevice.ACTION_PAIRING_REQUEST receiver onCreate()

val pairingRequestFilter = IntentFilter(BluetoothDevice.ACTION_PAIRING_REQUEST)
        registerReceiver(pairingReceiver, pairingRequestFilter)

on receiver set your pin using setPin() and call abortBroadcast()

val PAIRING_PIN=1234

private var pairingReceiver = object : BroadcastReceiver() {
        override fun onReceive(context: Context?, intent: Intent?) {
            val action = intent!!.action
            if (BluetoothDevice.ACTION_PAIRING_REQUEST == action) {
                val device: BluetoothDevice? =intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE)
                val type =intent.getIntExtra(BluetoothDevice.EXTRA_PAIRING_VARIANT, BluetoothDevice.ERROR)
                if (type == BluetoothDevice.PAIRING_VARIANT_PIN) {
                    device?.setPin(PAIRING_PIN.toByteArray())
                    abortBroadcast()
                }
            }
        }
    }

Don't forget to unregister receiver on onDestroy()

override fun onDestroy() {
        super.onDestroy()
        unregisterReceiver(pairingReceiver)
    }

if it doesn't work for you, try setting hight priority to receiver

val pairingRequestFilter = IntentFilter(BluetoothDevice.ACTION_PAIRING_REQUEST)          
pairingRequestFilter.priority = IntentFilter.SYSTEM_HIGH_PRIORITY - 1
            registerReceiver(pairingReceiver, pairingRequestFilter)

Also you can register a receiver with BluetoothDevice.ACTION_BOND_STATE_CHANGED to read status of pairing

val filter = IntentFilter(BluetoothDevice.ACTION_BOND_STATE_CHANGED)
        registerReceiver(receiver, filter)