question of add my own BLE service

RE: question of add my own BLE service

Sensors — Sat, 20 Feb 2016 18:19:11 GMT

What does it mean for the CCCD to be writeable? Is this to allow the client to turn on and off notifications?

RE: question of add my own BLE service

Valer_I — Tue, 25 Aug 2015 15:09:22 GMT

Have the same issue, from other thread we've got link to BT Core 4.2 volume 3, part G, section 3.3.3.3 (Client Characteristic Configuration) "Authentication and authorization may be required by the server to write the configuration descriptor. The Client Characteristic Configuration declaration shall be readable and writable."

It sounds a little bit tricky, because of quote "...may be required by the server to write..." So if server requires auth from CCCD, but on device configured as BLE_GAP_CONN_SEC_MODE_SET_OPEN(&cccd_md.write_perm); or vice versa the communication will crash? In my case the mode BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&cccd_md.write_perm); needed to preserve device from enabling notifications by not authorized server. And it works on some android devices but not all. Even more it could change behaviour on same device after reconnection. Please help.

RE: question of add my own BLE service

Ulrich Myhre — Mon, 28 Jul 2014 03:08:15 GMT

I'm not sure why the IAS service is not working, but the CCCD must be writable and readable per the Core Spec, and you will get an error when trying to add it with different permissions. You want to change the permissions of the attr_md variable, which is linked to the attribute itself and not the CCCD.