Disconnection after LLCP ping

[Cyril Praz]

Hello,

We have noticed that with an iPhone 11 with IOS 13.2. We have a lot of disconnection because our device simply didn't respond to a ping request.

Our device is an nRF51822 with SDK9.  Here is a trace showing a first succesful ping request followed by a failed one. After that there is a disconnection with reason 0x2A - BLE_HCI_DIFFERENT_TRANSACTION_COLLISION.

Do you know how is it possible to fix this issue?

[Kenneth]

Hi,

I suggest to send some dummy data (e.g. battery notification) every 5seconds to avoid the LL_PING_REQ to be sent from the peer. The LL_PING is only sent if the link have been inactive for a period of time to check that the link is still encrypted, so sending any data avoid that to occur.

Best regards,
Kenneth

[Cyril Praz]

We are going to apply this workaround but I am concerned  about why we have this problem now. SDK9 is becoming to be obsolete and we can expect to have more errors like this in the future?

[Kenneth]

This is not something you expect should happen often no, and in this case I expect that if you download the latest iOS beta release the problem is fixed (even if not documented in specific), because Apple do fix things like this in general:

https://developer.apple.com/documentation/ios_ipados_release_notes

[Cyril Praz]

We have checked and on the beta version the problem remain. I guess your workaround is the only solution for the moment.