How to maximize transmit power used on nRF52840?

[Ken58]

Hi,

Using nRF Connect SDK v3.3.0, Toolchain v3.3.0, nRF Connect for VS Code 2026.7.2128:  I want to configure maximum transmit power used by the nRF52840 on a nRF52840DK, nRF52840 Dongle, and a custom board using the nRF52840.

I have added CONFIG_BT_CTLR_TX_PWR_PLUS_8=y to my prj.conf file, but I see the following:

What am I missing?  I see CONFIG_HAS_HW_NRF_RADIO_TX_PWR_HIGH=y in the output file .config.

Thank you,

Ken

[Einar Thorsrud]

Hi Ken,

I second Rajeev K R , the only changfe needed is adding "CONFIG_BT_CTLR_TX_PWR_PLUS_8=y" to proj.conf. I verified this now on SDK 3.3.0 and a nRF52840 DK. This will automatically have CONFIG_HAS_HW_NRF_RADIO_TX_PWR_HIGH=y, as that is set based on the devicetree (see here and the dts for nRF52840 here). As this is not the case on your end, I wonder if you are building for another nRF52 series device by a mistake? Or alternatively if you have made some incorrect changes to the SDK files?

Br,

Einar

[Ken58]

Hi Einar,

My setup is using a standard nRF52840DK and agrees 100% with your links.  No changes to SDK files.  What else can I check?  Is there a possibility that the squiggles/error message in my prj.conf is not correct?  It does seem a little "sketchy" from time to time depending on what might be highlighted in the APPLICATIONS pane configurations/contexts.

Best regards,

Ken

[Einar Thorsrud]

Hi Ken,

It could be that there is an issue with the VS Code extension, but that also seems odd. Have you checked the generated .config for the application to see if CONFIG_BT_CTLR_TX_PWR_PLUS_8=y is set there? You can also check the actual Tx power by reading the TXPOWER register after the radio has been used (for instance after starting to advertise). You can for isntance do that with "nrfutil device read --address 0x4000150c --width 32 --direct".

If this stil fails on your end, can you share the build command and full build log?

[Ken58]

Hi Einar,

I think there may be a problem with the VS Code extension.  Here's what I can show:

1. The squiggles/error message in my prj.conf are present as shown above.
2. CONFIG_BT_CTLR_TX_PWR_PLUS_8=y is present in the .config file:
3. Here is the build log: 

4. Here is the TXPOWER register contents.  I didn't know I could do that with nrfutil.  Thanks a bunch for that tip!

So, I think that my code is transmitting with the power I want - which is good.  But, it looks like there is a problem in the development environment.

Please let me know what else I can do for you to help get to the bottom of this issue.

Thanks,

Ken

/cfs-file/__key/communityserver-discussions-components-files/4/3808.build.log

/cfs-file/__key/communityserver-discussions-components-files/4/5732_2E00_.config.txt

[Einar Thorsrud]

Hi Ken,

Yes, it seems clear this is only a VS Code related issue. Do you always see this? The Kconfig interpretatin should be based on the active build folder and I do no have any immediate suggestion on why this fails. Can you you generate support info as shown here and upload to the case?

 

It could also be interestign to see if there are any relevant issues in the VS Code problems tab?

[Ken58]

Hi Einar,

No, I do not always see this problem.  As I reply, I am not seeing the problem.  I will watch for it the next few days and get you the support information if it happens.

Thank you,

Ken