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  • Case ID: 278099
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Is setting CCCD enabled by default allowed by BT SIG?

jeffdev3

I have seen examples of enabling CCCD by default in the forum but I have not seen anyone say it is not allowed according to the BT SIG.

https://devzone.nordicsemi.com/f/nordic-q-a/63606/enabling-notification-by-default/259327#259327

In the BT spec section 3.3.3.3 it says:

The default value for the Client Characteristic Configuration descriptor value shall be 0x0000.

Will there be any problem qualifying my product if I enable CCCD by default on a custom service and characteristic?

  • 0

    Hi

    Will there be any problem qualifying my product if I enable CCCD by default on a custom service and characteristic?

    Custom services are not validated by qualification tests, so you will most likely get through qualification, but you would still be breaking the specification so it is obviously not something we would recommend. 

    Is there any particular reason you can't just have the client write this value after connection establishment?

    Best regards
    Torbjørn

  • 0 in reply to ovrebekk

    I am enabling CCCD every time after connection right now but I want to reduce the packets being transferred and eliminate some of the occasional problems on the phone side failing to enable CCCD.  My device bonds to the phone but it seems Android and iOS does not enforce the BT spec feature that CCCD state for bonded devices are saved.  I have seen Android phones enabling CCCD by default on the service changed characteristic also because it is sending the indication to my device in certain cases when I never enabled it.

  • 0 in reply to jeffdev3

    Hi 

    As I said we can't recommend anyone break the specification. Even if you pass compliance testing today the test might be changed in the future to check this specifically. 

    It is also hard to know how different clients (the phone in your case) will respond to receiving notifications when they haven't been properly enabled from their side. 

    If the phone is failing to enable the CCCD I believe that is the problem that needs investigating. 

    Best regards
    Torbjørn

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