BLE - Filter Accept List issue with nRF54LS05b and iOS/Android devices

[Stefan Schmidt]

Dear Nordic-Support,

 we are facing an issue with a nRF54LS05b and NCS v3.3.0:

The setup is a peripheral based on the nRF54LS05b and two centrals e.g iOS Phones A and B. Both phones bond with the peripheral. The peripheral sets up a Filter Accept List for reconnection (very similar to https://academy.nordicsemi.com/courses/bluetooth-low-energy-fundamentals/lessons/lesson-5-bluetooth-le-security-fundamentals/topic/blefund-lesson-5-exercise-2/#exercise-2-implement-bonding-and-a-filter-accept-list).

What we noticed is that the order in which the phones are bonded matters when we try to reconnect to the peripheral:

1. bond phone A
2. bond phone B
3. disable ble on phone A
4. advertise with the filter accept list

            > phone B does not reconnect

1. bond phone B
2. bond phone A
3. disable BLE on phone A
4. advertise with the filter accept list

          > phone B reconnects

This is reproducible. We see that both phones are added to the filter accept list.

When we advertise without the filter accept list, phone B reconnects (but this is not what we want. At that part of the software we only want bonded devices to get the updated information)

Is this a known issue? Do you have ideas how to further track this issue? Is there an option to enable logging for the evaluation of the filter accept list? I assume this is done on the radio side.

The relevant settings in prj.conf:

# Bonding / Security

CONFIG_BT_SMP=y

CONFIG_BT_BONDABLE=y

CONFIG_BT_MAX_PAIRED=8

CONFIG_BT_FILTER_ACCEPT_LIST=y

CONFIG_BT_SETTINGS=y

CONFIG_BT_ID_AUTO_SWAP_MATCHING_BONDS=y

CONFIG_BT_SMP_SC_PAIR_ONLY=n

CONFIG_BT_SMP_ENFORCE_MITM=n

# Let a Just Works re-pairing overwrite an existing unauthenticated bond so a

# phone that "forgot" the device re-bonds on the first try.

CONFIG_BT_SMP_ALLOW_UNAUTH_OVERWRITE=y

CONFIG_BT_CTLR_PRIVACY=y

CONFIG_BT_PRIVACY=y

NOTE: The same firmware build for the nRFL05 works as expected. The bonding order does not make a difference here!

Best regards

Stefan

[Stefan Schmidt]

You can reproduce that issue with the example from the ble course: https://academy.nordicsemi.com/courses/bluetooth-low-energy-fundamentals/lessons/lesson-5-bluetooth-le-security-fundamentals/topic/blefund-lesson-5-exercise-2/

When built with nrf54ls05dk/nrf54ls05b/cpuapp you can bond two devices, but you can only connect again with the one that was bonded first

[Stefan Schmidt]

Hi, maybe I give a detailed description here how to reproduce the issue:

I used the final application from lesson5-exercise2 of the course and two Smartphones (A + B)

1. The application advertises
2. Scan and connect with the Nordic App on Smartphone A
3. Enter the pin for the bonding
4. Disconnect Smartphone A from the peripheral
5. Start "open" advertising on the peripheral using the PAIRING button (I think button 2)
6. Scan and connect with the Nordic App on Smartphone B
7. Disconnect Smartphone B from the peripheral
8. Now both Smartphones are added to the filter accept list
9. Use the Nordic App on Smartphone A to connect to the peripheral
10. Disconnect
11. Use the Nordic App on Smartphone B to connect to the peripheral
    1. works on nRF54L05
    2. does not work on nRFLS05b