NCS: Softdevice+Mesh+Ext. Advertising -> TX Power Control?

[mesh777]

Hello,

I have trouble again with TX Power control. This time using Softdevice Controller and NCS2.6.0.

Previous issue which was solved (this was using Zephyr Controller):  NCS Mesh: TX Power register value does not change when changing TX Power via HCI 

Is there a common solution to control TX Power runtime, when running Mesh + Extended Advertising and Softdevice controller?

Thanks in advance! :)

[Hieu]

Hi mesh777,

You should be able to control the TX Power following the method demonstrated in the Bluetooth: HCI Power Control sample.

Please note that the SoftDevice Controller only raise the TX Power momentarily for the radio action, and then will set it back to 0. A crude way I used to confirm things are working is to repeatedly print out the content of the TXPOWER register.

Hieu

[mesh777]

Hieu said:

Please note that the SoftDevice Controller only raise the TX Power momentarily for the radio action, and then will set it back to 0

What is the reason of such behaviour? Does it mean that TX Power needs to be reconfigured continuously or it is handled by Softdevice automatically?

The reference sample does not take into account multiple AVD sets, when EXT ADV is enabled. Maybe Conn Handle somehow can be determined to configure each set?

[mesh777]

But why to reconfigure it always back to 0dBm then?

Or it is related to not retained register value due transceiver power modes or something?

[Hieu]

mesh777 said:

But why to reconfigure it always back to 0dBm then?

Or it is related to not retained register value due transceiver power modes or something?

TXPOWER-set-to-0 is just a known state to make it simpler to support multiple TX Power for different activities. Examples include but not limited to other BLE activities, or user application's MPSL timeslot API use, or Power Envelope Control.

[Hieu]

I also notice previously I use misleading words in this sentence:

Hieu said:

For Mesh, I tweak the logic a little like below and I can observe TXPOWER being 8 all the time.

I mean "all the time" as in "in a lot of instances," not "always". My apology if that confused you. I will edit it so that it doesn't confuse any future readers.

[mesh777]

Ok I see. Thanks again for rapid and informative responses.

We need to perform spurious emission testing, maybe there are any Nordic guidelines upon that especially related to test firmware?

[Hieu]

I'm happy to help. I also learn new things and refresh a lot of the rusty bits of knowledge while answering your questions too. 

mesh777 said:

We need to perform spurious emission testing, maybe there are any Nordic guidelines upon that especially related to test firmware?

This is a rather different topic. May I ask you to open a new case for this?

[mesh777]

Ok, ill try to search for similar topic regarding my last question at first.

Final thoughts -> such basic feature as TX Power control still causes issues, maybe it should be brought forward to Softdevice/NCS developers as this is not first time I am working on resolving TX Power control:)

[Hieu]

Do you mean dynamic/run-time control of TX Power for Bluetooth Mesh? If so, we have registered it

As for other regular BLE activities, I believe the dynamic TX Power control works fine.

[mesh777]

Please forward both findings, also the one that with static configuration its confusing to see that register is switched back to 0 all the time without any good reason.

[Hieu]

Yes, we have recorded them. I can see how reading TX Power and seeing 0 would be concerning. I will talk with the documentation team to find a way to present the fact more clearly.