MPSL ASSERT 106, 701 and SoftDevice Controller assert 48, 1403

[Robin J]

We are using nRF Connect SDK 2.9.1, Zephyr. The hardware used is a nrf52840dk, rev2.

We have a proprietary protocol that is running concurrently with BLE and uses MPSL API for radio access.

We are now facing a problem when doing DFU over BLE using MCUmgr and BLE as the transport layer. We've followed the "FOTA updates on nRF52 Series" documentation to setup DFU over BLE. The target flash area to store the uploaded firmware to is the internal flash. 

The problem we get is that either MPSL or the SoftDevice Controller asserts during transfer of the firmware. It is either "MPSL ASSERT 106,701" or "SoftDevice Controller ASSERT 48, 1403".

Any suggestion on what it can be that causes the asserts?

[Einar Thorsrud]

Hi,

The asserts are related to scheduling in the MPSL and SoftDevice controller, but we need to look a bit more into it to be more specific. You write this issue happens only during DFU over BLE, are the BLE connection parameters changd at this point, or perhaps there is longer packets and/or several packets per connection event? (So that BLE takes more time)? Are there any other factors that stand out when you see this issue?

[Robin J]

Hi,

I've only seen it happen during the DFU over BLE transfer. I don't think the connection parameters are changed during the transfer. I'm using the Kconfig options described in FOTA updates on nRF52 to enable MCUmgr SMP over BLE and the upload is done from the nRF Device Manager mobile app.

One thing to note is that I only see the asserts when our proprietary protocol is running and using timeslots at the same time as the BLE DFU transfer is being done. If our protocol is disabled, I don't see any asserts.