BLE_GAP_EVT_DISCONNECTED doesn't occur when connection is terminated after receiving LL_VERSION_IND

[Remo]

Hi

We established a connection with a mobie phone as central device and an nRF52832 or nRF52833 as peripheral device.
If we afterwards try to terminate the connection on the nRF with sd_ble_gap_disconnect(), the BLE_GAP_EVT_DISCONNECTED does not occur.

We have seen with a Bluetooth sniffer, that the SoftDevice sends the LL_TERMINATE_IND right after the central device has sent the LL_VERSION_IND.
Is it possible that the SoftDevice could not trigger BLE_GAP_EVT_DISCONNECTED because it is somehow stuck because it could not answer the LL_VERSION_IND?

If we add a small delay so that the connection is terminated after the SoftDevice answered the LL_VERSION_IND, the BLE_GAP_EVT_DISCONNECTED is triggered.

The problem occurred on the nRF52832 (S132 V7.2.0) and on the nRF52833 (S140 V7.2.0).

Do you know this behavior?

Many thanks in advance.
Remo

[Remo]

Hi Einar

Thank you for the explanation. Do you know if this implemantation detail will be fixed if there will be a new SoftDevice release?

Best regards

[Einar Thorsrud]

I cannot say for sure it it will be included in a new release or not, but generally you should not expect large updates to the SoftDevices going forward (due to most new activity happening with the nRF Connect SDK). Also, the disconnected event only happens after the peer has acknowledged the LL_TERMINATE_IND, and if this does not happen for instance due to the ACK being lost on air, you will also have to wait for the timeout, so you anyway need to handel that condition.

[Remo]

Ok, thank you.