BLE notification subscription gets 133
1 Android phone (N5X 6.0.1) runs on a BLE server and the other (N5X O) is signed. Trait notification can be enabled, however, in the record descriptor part, I keep getting 133.
Server.java
private void createServer() {
bluetoothGattServer = bluetoothManager.openGattServer(this, serverCallback);
BluetoothGattService service = new BluetoothGattService(Constants.SERVICE,
BluetoothGattService.SERVICE_TYPE_PRIMARY);
characteristic =
new BluetoothGattCharacteristic(Constants.CHARACTERISTIC,
BluetoothGattCharacteristic.PROPERTY_NOTIFY,
BluetoothGattCharacteristic.PERMISSION_READ | BluetoothGattCharacteristic.PERMISSION_WRITE);
// public static UUID DESCRIPTOR = UUID.fromString("00002902-0000-1000-8000-00805f9b34fb");
characteristic.addDescriptor(new BluetoothGattDescriptor(Constants.DESCRIPTOR,
BluetoothGattCharacteristic.PERMISSION_READ | BluetoothGattDescriptor.PERMISSION_WRITE));
characteristic.setWriteType(
BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT);
service.addCharacteristic(characteristic);
bluetoothGattServer.addService(service);
}
private BluetoothGattServerCallback serverCallback = new BluetoothGattServerCallback() {
@Override
public void onConnectionStateChange(BluetoothDevice device, int status, int newState) {
super.onConnectionStateChange(device, status, newState);
Log.d(TAG, "onConnectionStateChange " + device.getName() + " " + status + " " + newState);
if (newState == BluetoothGatt.STATE_CONNECTED) {
bluetoothDevice = device;
} else if (newState == BluetoothGatt.STATE_DISCONNECTED) {
bluetoothGattServer.cancelConnection(bluetoothDevice);
bluetoothGattServer.close();
}
}
};
private void sendData(String message) {
characteristic.setValue(message);
bluetoothGattServer.notifyCharacteristicChanged(bluetoothDevice, characteristic, true);
}
All other UUIDs were generated from here .
Client.java
device.establishConnection(false)
.flatMap(bleConnection -> bleConnection.setupNotification(Constants.CHARACTERISTIC))
.flatMap(onNotificationReceived -> onNotificationReceived)
.subscribe(data -> {
Log.d(TAG, "data: " + data);
}, throwable -> {
Log.d(TAG, "data error " + throwable);
});
logcat
05-15 15:26:50.097 D/BluetoothGatt: setCharacteristicNotification() - uuid: 8d7dda32-3759-11e7-a919-92ebcb67fe33 enable: true
05-15 15:26:50.105 D/RxBle#Radio: QUEUED RxBleRadioOperationDescriptorWrite(60042487)
05-15 15:26:50.110 D/RxBle#Radio: FINISHED RxBleRadioOperationServicesDiscover(231218312)
05-15 15:26:50.112 D/RxBle#Radio: STARTED RxBleRadioOperationDescriptorWrite(60042487)
05-15 15:27:20.119 D/RxBle#Radio: FINISHED RxBleRadioOperationDescriptorWrite(60042487)
05-15 15:27:20.121 D/BluetoothGatt: setCharacteristicNotification() - uuid: 8d7dda32-3759-11e7-a919-92ebcb67fe33 enable: false
05-15 15:27:20.126 D/RxBle#BluetoothGatt: onDescriptorWrite descriptor=00002902-0000-1000-8000-00805f9b34fb status=133
05-15 15:27:20.129 D/BLE: data error BleGattDescriptorException{macAddress=42:EE:5A:C6:C1:F0, status=133 (0x85 -> https://android.googlesource.com/platform/external/bluetooth/bluedroid/+/android-5.1.0_r1/stack/include/gatt_api.h), bleGattOperationType=BleGattOperation{description='DESCRIPTOR_WRITE'}}
Note. If I use the native Android API, I can subscribe and receive notifications without having to write to the descriptor.
update: interesting thing, although the process of writing the descriptor is in progress (takes about 30 seconds until it returns with an error) I can get onCharacteristicChanged
.
update2: added callback and write to feature code
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The Bluetooth Core specification says that if a trait supports notifications, it should contain a configuration descriptor for the client's characteristics and only start notification when the CCC descriptor is written with the correct value.
It seems that there is a problem in your configuration which manifests itself as status = 133
. It seems that you made a mistake while setting properties on characteristic
. My guess is that you want to have a characteristic that you can read, write, and set notifications - in this situation it would look like this:
characteristic = new BluetoothGattCharacteristic(Constants.CHARACTERISTIC, BluetoothGattCharacteristic.PROPERTY_READ | BluetoothGattCharacteristic.PROPERTY_WRITE | BluetoothGattCharacteristic.PROPERTY_NOTIFY, BluetoothGattCharacteristic.PERMISSION_READ | BluetoothGattCharacteristic.PERMISSION_WRITE);
Edit. Remember that if central asks to enable notifications, it tries to write a Client Characteristic Config descriptor. If it is not a customization request NO_RESPONSE
, then the central one expects a response.
The correct solution is to add a callback to onDescriptorWriteRequest
and send the response to the central one:
BluetoothGattServerCallback serverCallback = new BluetoothGattServerCallback() {
// (...)
@Override
public void onDescriptorWriteRequest(BluetoothDevice device, int requestId, BluetoothGattDescriptor descriptor,
boolean preparedWrite, boolean responseNeeded, int offset, byte[] value) {
super.onDescriptorWriteRequest(device, requestId, descriptor, preparedWrite, responseNeeded, offset, value);
// validate if the request is exactly what you expect if needed
bluetoothGattServer.sendResponse(device, requestId, BluetoothGatt.GATT_SUCCESS, offset, value);
}
// (...)
};
Potential workaround
Some Chinese manufacturers do not meet the Bluetooth Core specification and do not have a CCC descriptor on the characteristics that send notifications. If you can receive notifications without installing CCC, then you can use compatibility mode RxBleConnection.setupNotifications(characteristic, NotificationSetupMode.COMPAT)
, although it is not recommended and you need to attach the correct fix to the configuration.
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