Bluetooth Advertising messes up after a few days of no power

[SohamGhugare]

Hello Team,

We have noticed a very weird issue with the nRF5340 Audio DK. After flashing the audio application code given by nordic, everything works perfectly fine. No build errors or flash errors. However if the board is left unattended or unpowered for a few days (2-3 days), the bluetooth advertising messes up completely. On checking the logs, it shows directed advertisement has been timed out, switching to normal advertisement. This is instantly fixed if we just re-flash the firmware. Here's the details of the SDK and toolchain.

Toolchain Version: 3.0.1

SDK Version: 3.0.1

We have tried this on all the nRF5340 Audio DK's we have and all of them face the same issue. How can this be fixed?

[SwRa]

Hi Soham,

I will look into this and get back to you.

Regards,

Swathy

[SwRa]

Hi Soham,

Could you let me know the detailed steps to replicate the issue. Are the unicast client and server, both nRF5340 ADK, or is the unicast client a phone.?

Also, please do share the log from Unicast client and server side.. 

Regards,

Swathy

[SohamGhugare]

Hey Swathy,

For replicating the issue you just flash the unicast server code on nRF5340 Audio DK and leave it without power for a day or so. The board will automatically switch to Normal advertising from Directed advertising when you repower it after a day. 

The unicast client is a mobile phone with BLE Audio enabled. Specifically the Samsung S23 Ultra, we are able to stream audio and everything perfectly fine.

For the logs, what kind of logs are you looking for (build logs, flash logs, others, etc)

Regards,

Soham

[SwRa]

Hi Soham,

After a headset is bonded, it will always use direct-ADV after being disconnected for a short time and then switch to normal ADV. What you saw could be the ordinary behavior. Toggling the power on the ADK confirms this.. However, we will leave it without power overnight and test it once more.

Regards,

Swathy

[SohamGhugare]

Hi Swathy,

Yes, I'm aware about the directed adv switching to normal adv after some time, but this time duration is usually fixed and set by the audio application. However in our case when the board is not powered for a bit, it switches from directed to normal adv within 2 seconds of powering on which I think is unusual.

Regards,

Soham