unknown UUID error

[AndrewAWG]

I'm trying to get notifications from a peripheral after connecting to it. I used the central_hr example in zephyr, and I changed the UUIDs used to both primary HR service and characteristics to the ones that I see using NRF connect on iOS. when I do this, the central connects successfully but it gives me this error.

What I'm wondering is that it doesn't enter the discovery function, it always fails in the connected callback funtion (code below).

[Einar Thorsrud]

Hi,

It looks like bt_gatt_discover returns -EINVAL (-22). That can be returned for a couple for different reasons, but as you chnanged some UUIDs I would assume an issue there. Perhaps a mixup between 16 bit and 128 bit UUIDs? You can use a debugger to see more precisely what went wrong by checking in bt_gatt_discover() in zephyr/subsys/bluetooth/host/gatt.c (or you can add some logging there if that is easier).

[AndrewAWG]

Thank you Mr Thorsrud, I will debug the code and tells you what I got. 

[AndrewAWG]

I did what you told me here, and now I get notifications. But I can't understand what is meant by Attribute handle [num](figure below)

[Einar Thorsrud]

Hi,

That is good news. The attribute handle itself has no meaning, but it is a handle or ID or identifier if you like, that you read during service discovery to know what it represents (like an an attribute for a specific characteristic in a specific service).

[AndrewAWG]

Okay, thanks a lot. As I understand the address showed on the figure,  points to the data that I get from the peripheral. is there any way to access these data. As accessing them using & shows nothing meaningful.