Client Characteristic Configuration Descriptor uuid

RE: Client Characteristic Configuration Descriptor uuid

endnode — Thu, 07 Sep 2017 01:20:08 GMT

You are asking ME what YOUR code is doing?:) If you don't know then simply don't put it to your app;) If you are running getDescriptor function with non-existing UUID then I expect it will return some error. Unfortunately I'm not android developer so I neither help you with this function call nor with second question about how to verify Server Notification/Indication status from GATT Client side on top o Android API. I would say Google should be your friend (also this forum has search window and there is good chance that one of 25k Q&S contains Android code which solves your problem).

RE: Client Characteristic Configuration Descriptor uuid

frodyteen — Thu, 07 Sep 2017 01:10:46 GMT

@endnode 00002902-1212-efde-1523-785fef13d123, this UUID does not exist on my server side. So, what does ths line (mReadCharacteristic.getDescriptor(UUID.fromString("00002902-1212-efde-1523-785fef13d123"))) do in my android side? Also, how can I verify that I turned on my notification on my android side? thank you for your help!

RE: Client Characteristic Configuration Descriptor uuid

endnode — Wed, 06 Sep 2017 20:59:50 GMT

Answers:

Yes indeed, CCCD has UUID assigned by BT SIG so it is 16-bit (but of course you can expand it with BT SIG UUID base to full 128 bits if you really need;). There is no problem that each of CCCDs has the same UUID because they have different handle IDs (and that's how (G)ATT methods address targets on the stack) and in fact they must be the same because otherwise how you would know that's CCCD???
Not sure it's evident what are you doing in your Android app. CCC descriptor should be accessible through dedicated BLE API call and in fact your app should not care what and how exactly Android (G)ATT stack works with it, you simply ask to enable or disable Notifications (or Indications) and it will happen. You should never talk to that by UUID and it's question what the hell you want to achieve with line mReadCharacteristic.getDescriptor(UUID.fromString("00002902-1212-efde-1523-785fef13d123"))? That UUID doesn't exist on server side, does it?