BLE connection issue with iPad A16 – Control Opcode 0xFF

Question

HardikBhavsar OP

Created 2w

Replies 1

Boosts 1

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We are testing BLE connectivity between a custom device (nRF52832, nRF5 SDK) and the latest iPad A16.

Setup:

Peripheral: nRF52832 running Nordic’s SoftDevice (nRF5 SDK v13) . Central: iPad A16 (Latest iPadOS 18.6.2).

Issue:

During the connection procedure, the iPad sends a Link Layer Control PDU with Opcode 0xFF. This is a vendor-specific LL control opcode. Our peripheral does not respond, since the Nordic SoftDevice does not implement handling for 0xFF. As a result, the link stability is affected (connection may drop / negotiation fails).

Observations:

With older iPads and iPhones (A14/A15 chips), no such control opcode is sent — connection and notifications work fine. Only the iPad A16 sends this vendor-specific opcode. Nordic’s SoftDevice responds to standard LL control opcodes, but ignores vendor-specific ones.

Questions:

Is this 0xFF LL control PDU expected behavior on A16 devices? Should peripherals ignore vendor-specific LL opcodes, or is a response required for stable connection? Are there known changes in BLE Link Layer negotiation with iPad A16?

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Answer 1

Engineer OP

Apple

1w

We are tracking some similar issues with the A16 iPads, and looking for a fix in an upcoming iOS/iPadOS

While we believe your issue could also be resolved with an upcoming fix, it does not hurt to have more data points, as the remote devices the iPads interact with vary, and would be good to cover as much as we can.

To that end, we would like to see some diagnostic logs to understand why this might be happening on your end. To create that log, please go to https://developer.apple.com/bug-reporting/profiles-and-logs/ and follow the instructions for Bluetooth for iOS to install a logging profile on your device. Then, once the logging profile is installed: reproduce the problem, keeping track of the actual time of the actions you take and the result you see. please have your app use os_log() statements to indicate what CoreBluetooth actions it is taking if you have a small project demonstrating the issue, please include that. Once the problem is reproduced, follow the instructions at the above link to trigger a sysdiagnose.

Once you have all the information, please file a Feedback report at http://feedbackassistant.apple.com and let me know the Feedback ID here (@ mention me for expediency), and I will forward this to the team.

Argun Tekant /  DTS Engineer / Core Technologies

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