User Description Descriptor Example

[Hein]

Hi guys,

Is there a recent example that shows how to add user description descriptors to characteristics on S132 V5.1 ? I have tried the various methods I could find in the Q&A, but have not had any luck. 

Thanks! 

[Hein]

To add a little bit more detail, I tried manually adding the description descriptor by editing the characteristic metadata as per below:

 memset(user_desc, 0, 10);
 strcpy(user_desc, "Test");
 char_md.p_char_user_desc = (uint8_t *) user_desc;
 char_md.char_user_desc_size = 4;//strlen(user_desc);
 char_md.char_user_desc_max_size = 4;//strlen(user_desc);

and when that didn't work, I tried doing it through the sd_ble_gatts_descriptor_add() function

In both cases, I tried doing it with the first characteristic in my service, and in both cases, the second characteristic was broken by the code. The second characteristic is a 20 byte read and notify with cccd characteristic. When I periodically update the characteristic from a timer in the firmware, the messages show up correctly at the central device. As soon as I try to add the description descriptor to the first characteristic, the second characteristic is broken and the messages no longer show up correctly at the central device. 

I can post a full code listing it that would help, but it would be great if there is a known good example somewhere that I can have a look at.

[Hein]

Heeelllloooooooo is there anybody out there ?

[Edvin]

Hello,

Sorry for the late reply. May I ask what you intend to do? Are you trying to create a characteristic with notification?

Sorry that this is not a thorough answer. We are a bit short staffed these days. 

But yes. Are you sure that it is the descriptor you want to change, and not the cccd?

Best regards,

Edvin

[Hein]

Hi Edvin,

I am wanting to add a 'User description descriptor' to an existing characteristic. The idea is that if you connect to the device with a generic app like LightBlue or your nRF Connect app, the app can display human readable text names for the characteristics. Searching through the Q&A, it looks like there are 2 way to do this, as described above, but neither way seems to work ?

Appreciate your input ! Thanks

[Edvin]

What does your sd_ble_gatts_descriptor_add() return?

Does it return something other than 0 (NRF_SUCCESS)? Or is the issue that you don't see the name "test" on your central device?

 

BR,

Edvin