Subscribe to a BLE Gatt notification Android

Question

I´m developing an BLE app, based on the Gatt sample project provided by google: https://developer.android.com/samples/BluetoothLeGatt/index.html. So, I can send data writing in

Answer 1

In addition to the accepted answer, I had to set the Characteristic to WRITE_TYPE_DEFAULT when subscribing to peripheral running on OS X.

characteristic.setWriteType(BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT);

Answer 2

To receive notification in Android you need to set characteristic notification to true

gatt.setCharacteristicNotification(characteristic, true);

You also need to set the client characteristic configuration descriptor 0x2902

// 0x2902 org.bluetooth.descriptor.gatt.client_characteristic_configuration.xml
UUID uuid = UUID.fromString("00002902-0000-1000-8000-00805f9b34fb");
BluetoothGattDescriptor descriptor = characteristic.getDescriptor(uuid);
descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
gatt.writeDescriptor(descriptor);

A better API would be for setCharacteristicNotification to set the descriptor, but unfortunately it doesn't seem to work that way.