Where is the function which sets the cccd?

[Mitch996]

Hello, I'm using an android device to set cccd, it worked when I was running the project on nrf514xx @s110, it no longer does on nrf52840 S140, so now I wanna make sure the program actually dont skip the part that sets the cccd.

So where in the library API can I find it? Which switch case? Which API function? I imagine it is a part of a gatt call back somewhere, but I can't quite tell where.

I hope it's not deeply hidden in the SD and it's impossible to locate.

Also, the other question I asked here can provide some more background:

devzone.nordicsemi.com/.../

[endnode]

Hi Mitch, how you describe it this seems to be more Android problem. What radio sniffer trace says? Is android phone really writing proper 16-bit value to CCCD handle? Is it using Write Request not Write Command (which seems to be forbidden by BT SIG spec for writing to CCCD and so Nordic enforces it in their latest soft devices (see this Q&A thread for more))?

Otherwise when it comes to S140 API you should wait for BLE_GATTS_EVT_WRITE and filter it by target handle and value and act accordingly.

[endnode]

One more note to this new change in SD behavior: previously any of GATT Write methods work (yes, there are more types of various (G)ATT Methods defined in BT SIG specification, read that or some training, it's useful;) to change value of 16-bit CCCD handle. If it wasn't protected for unauthenticated Writes etc. And you always got event callback to your application's SD event handler (like many others GATT events when they happen in SD). However now SD ignores Write CMD to CCCD and doesn't (logically) notify application, only Write Request will cause that. This can again easily explain what you see (and that's why laziness of not getting RF trace prevents you to solve it for couple of days;).