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]

I'm not Android guru but I would say it should be managed by Android underneath and your code is fine. Also it's absolutely unsure this is your problem. Seeing what really goes over the radio would give you more clues. Then you can dig into why Android doesn't follow the spec or why Nordic things BT SIG spec insists on using GATT Write Request (or sometimes called Write with Response) and doesn't allow Write Command (or Write without Response if you want). Unfortunately my only sources on this topic are these links from this forum, I have neither time nor resources to test all this on nRF5x and phones any time soon...