Android-enable notification client side, CCCD & UUID.

RE: Android-enable notification client side, CCCD & UUID.

Parita — Fri, 26 Jul 2019 08:35:35 GMT

[quote userid="8863" url="~/f/nordic-q-a/17785/android-enable-notification-client-side-cccd-uuid"]BATTERY_LEVEL_CHARACTERISTIC_UUID[/quote]

Can anyone describe what will be this and how to get this

RE: Android-enable notification client side, CCCD & UUID.

Pradeesh — Wed, 24 May 2017 10:18:59 GMT

BluetoothGattCharacteristic chars = getCharacteristic(uuidToEnableNotification); mBluetoothGatt.setCharacteristicNotification(chars, true); BluetoothGattDescriptor descriptor = chars.getDescriptor(CCCD_UUID); descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE); Log.d("check", descriptor.getValue().toString()); mBluetoothGatt.writeDescriptor(descriptor);

no error and notification is also not sent properly

RE: Android-enable notification client side, CCCD & UUID.

Torsten Robitzki — Wed, 16 Nov 2016 13:41:30 GMT

There are 128-bit representation for 16-bit UUIDs and I think, the Android API can cope just with 128-bit UUIDs (but I might be wrong).

RE: Android-enable notification client side, CCCD & UUID.

Yacire — Wed, 16 Nov 2016 13:36:31 GMT

It works, Thanks for your help Torsten.

RE: Android-enable notification client side, CCCD & UUID.

Torsten Robitzki — Wed, 16 Nov 2016 13:33:41 GMT

The UUID should be 0x2902.:

here some code-snippets from an android project:

static final private UUID CCCD_ID = UUID.fromString("000002902-0000-1000-8000-00805f9b34fb");
final BluetoothGattDescriptor cccd = rccp_char.getDescriptor(CCCD_ID);
cccd.setValue(BluetoothGattDescriptor.ENABLE_INDICATION_VALUE)

HTH

RE: Android-enable notification client side, CCCD & UUID.

Yacire — Wed, 16 Nov 2016 13:27:25 GMT

Hi Torsten,

Thanks for your answer. There is already a CCCD in my server.The code in the server side is OK, i tested it with nrfConnect. But when i test with my Android App, it doesn't work.

What is this 16-bit UUID for CCCD ? maybe this is this UUID which is needed in this function :

bluetoothGattCharacteristic.getDescriptor( UUID.fromString(here_16bit_UUID_for_All_CCCD));

Edit_1: Ok, in the excellent tutorial by Martin Bors-Lind, he speaks about a UUID for all CCCD : the 16_bit value is : 0x2902.

I will test with this value int the getDescriptor() method.

RE: Android-enable notification client side, CCCD & UUID.

Torsten Robitzki — Wed, 16 Nov 2016 12:59:53 GMT

Not all characteristics have a CCCD by default. You have to make sure, that the GATT server provides a CCCD for the characteristic. If you have a ble sniffer, you could go and watch the service and characteristic discovery between client and server and see, if there is a CCCD and if the correct attribute bits are set within the characteristic descriptor.

You can not address a specific CCCD by UUID, as all CCCD have the very same 16-bit UUID. You have to lookup the characteristic, that contains the CCCD and then search through all attributes of that characteristic. But that is something that should have been done by Android for you.