Android, How can I make BLE device to paired devic

Question

Before GATT, createRfcommSocketToServiceRecord, createInsecureRfcommSocketToServiceRecord

methods can make paired device,

but GATT has no option about paired device, only use BluetoothDevice.connectGatt(...)

I want to make a paired device if it's connected already.

thx.

Answer 1

As far as I know, to initiate a pairing procedure in BLE there are two ways:

1) From API 19 and up you can start the pairing by calling the mBluetoothDevice.createBond(). You don't need to be connected with the remote BLE device to start the pairing process.

2) When you try to do a Gatt operation, let's take for example the method

mBluetoothGatt.readCharacteristic(characteristic)

If the remote BLE device needs to be bonded to do any communication then when the callback

onCharacteristicRead( BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status)

gets called its status parameter value will be equal to either GATT_INSUFFICIENT_AUTHENTICATION or GATT_INSUFFICIENT_ENCRYPTION, and not equal to GATT_SUCCESS. If this happens then the pairing procedure will start automatically.

Here is an example to find out when it fails once the onCharacteristicRead callback gets called

@Override
public void onCharacteristicRead(
        BluetoothGatt gatt,
        BluetoothGattCharacteristic characteristic,
        int status)
{

    if(BluetoothGatt.GATT_SUCCESS == status)
    {
        // characteristic was read successful
    }
    else if(BluetoothGatt.GATT_INSUFFICIENT_AUTHENTICATION == status ||
            BluetoothGatt.GATT_INSUFFICIENT_ENCRYPTION == status)
    {
        /*
         * failed to complete the operation because of encryption issues,
         * this means we need to bond with the device
         */

        /*
         * registering Bluetooth BroadcastReceiver to be notified
         * for any bonding messages
         */
        IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_BOND_STATE_CHANGED);
        mActivity.registerReceiver(mReceiver, filter);
    }
    else
    {
        // operation failed for some other reason
    }
}

Other people mentioning that this operation starts the pairing procedure automatically: Android Bluetooth Low Energy Pairing

And this is how the receiver can be implemented

private final BroadcastReceiver mReceiver = new BroadcastReceiver()
{
    @Override
    public void onReceive(Context context, Intent intent)
    {
        final String action = intent.getAction();

        if (action.equals(BluetoothDevice.ACTION_BOND_STATE_CHANGED))
        {
            final int state = intent.getIntExtra(BluetoothDevice.EXTRA_BOND_STATE, BluetoothDevice.ERROR);

            switch(state){
                case BluetoothDevice.BOND_BONDING:
                    // Bonding...
                    break;

                case BluetoothDevice.BOND_BONDED:
                    // Bonded...
                    mActivity.unregisterReceiver(mReceiver);
                    break;

                case BluetoothDevice.BOND_NONE:
                    // Not bonded...
                    break;
            }
        }
    }
};