RE: iPhone11 causing SD to disconnect with disconnected reason - BLE_HCI_DIFFERENT_TRANSACTION_COLLISION (0x2A)

Einar Thorsrud — Fri, 08 Nov 2019 13:00:09 GMT

Thank you for updating us.

RE: iPhone11 causing SD to disconnect with disconnected reason - BLE_HCI_DIFFERENT_TRANSACTION_COLLISION (0x2A)

kbarnett — Fri, 08 Nov 2019 08:50:00 GMT

Updating the iPhone11 to iOS13.2.2 has fixed the issue. I no longer see any 0xFF Link Layer requests from the iPhone11 or dropped connections.

RE: iPhone11 causing SD to disconnect with disconnected reason - BLE_HCI_DIFFERENT_TRANSACTION_COLLISION (0x2A)

Einar Thorsrud — Tue, 05 Nov 2019 13:20:18 GMT

Hi,

There was a severe issue with iPhone 11 where it ignored ATT packets in the first connection event. So if the nRF sent an ATT packet in the first connection event, this was asked by the iPhone 11, but ignored, leading to an ATT timeout 30 seconds later. This has been fixed in iOS 13.2 (the fix is that the iPhone does not ack the packet received in connection event 0, so that it is retransmitted in the next connection event, where it is handled properly). This issue first with most of your description, but not BLE_HCI_DIFFERENT_TRANSACTION_COLLISION. In this case, you will get a disconnect with reason BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION. Can you test upgrading to iOS 13.2 on the iPhone 11 to verify if this is it and that it is fixed?

The BLE_HCI_DIFFERENT_TRANSACTION_COLLISION is probably a different matter. This indicates (from spec): "The Different Transaction Collision error code indicates that an LMP transaction or LL Procedure was started that collides with an ongoing transaction". I have not seen reports of this with iPhone 11 earlier.

Since this is a bit odd, and we know there were several potentially relevant BLE issues in early iOS 13 versions, can you test again with iOS 13.2 on all devices?