Fail to interact with custom characteristics when its UUID is different from its service

RE: Fail to interact with custom characteristics when its UUID is different from its service

Sigurd — Thu, 31 Jan 2019 14:41:51 GMT

If you wanted to create a custom service with the Bluetooth SIG defined UUID base, and with your own custom 16-bit UUID value / octets 12-13 of 128-bit base UUID, then you would normally need to pay a fee to Bluetooth SIG for that. See this page. But this is not the case here, since you are actually using the FIDO UUID.

I did a quick test here, and it seems to only be hanging when using FIDO UUID(0xFFFD). It could be a bug in the app, or maybe more likely that Android core expect certain requirements to be fullfiled in accordance with the FIDO Bluetooth Specification v1.0 in order to interact with the service/characteristic.

RE: Fail to interact with custom characteristics when its UUID is different from its service

Dko — Thu, 31 Jan 2019 09:17:08 GMT

Thanks for your answer Sigurd. May I ask why so ? I am actually implementing an U2F service and it seems to be the expected UUID for this service.
Moreover, it works fine with the Desktop nRF Connect. It only fails on the Mobile app.

RE: Fail to interact with custom characteristics when its UUID is different from its service

Sigurd — Thu, 31 Jan 2019 09:09:53 GMT

Seems to be happening because you are using the predefined Bluetooth Base UUID that is used for the predefined services.(0000XXXX-0000-1000-8000-00805f9b34fb). You should not be using this UUID for custom services.

RE: Fail to interact with custom characteristics when its UUID is different from its service

Dko — Mon, 28 Jan 2019 14:27:37 GMT

It looks like a bug in the mobile app.
I bought a nrf52840 to be able to use the desktop app and I can successfully read and write the characteristics...
Can anyone confirm ?

RE: Fail to interact with custom characteristics when its UUID is different from its service

Nguyen Hoan Hoang — Sat, 26 Jan 2019 21:32:31 GMT

I've always though it has to be the same base. Seems like it doesn't have to. Then there is no problem in this case.

RE: Fail to interact with custom characteristics when its UUID is different from its service

Dko — Sat, 26 Jan 2019 09:31:53 GMT

Thanks for the quick reply. However before posting my question I came across these topcis and it was my understanding that it was actually possible to have different base UUIDs for service and characteristics:

Did I miss something ?

RE: Fail to interact with custom characteristics when its UUID is different from its service

Nguyen Hoan Hoang — Fri, 25 Jan 2019 16:40:01 GMT

The service and characteristics must belong to the same base uuid. You can change the 16bits value for the service/char uuid. Assuming your base uuid is CAFE0000-1234-1234-1234-123456789000, your service/char uuid is the xxxx values CAFExxxx-1234-1234-1234-123456789000