Why Low-Power feature cannot be enabled in Zephyr BLE Mesh

[Omid]

Hello, 

I am trying to set up low power nodes in my mesh network.
To do so, I edited the prg.config file to enable this feature as:

CONFIG_BT_MESH_LOW_POWER=y

And then, I tried to check if this feature is enabled by checking the information on the NRF mesh app. 

The app said it is disabled. 

Next, I tried  bt_mesh_lpn_set() in the main.c file, but still the problem persists. I am wondering how I can fix this issue.


Thanks

[Joakim Jakobsen]

Hi. 

Could you add some information about which SDK version you are working with which sample are you using to test this?

If you take a look at the Mesh Light switch example (https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/bluetooth/mesh/light_switch/README.html), this sample provides Low Power node support.

Br, 
Joakim

[Omid]

Hi Joakim, I have been using nrf 52840 sdk 3.0.0 and 2.0.1.

I am using the zephyr mesh example: https://github.com/zephyrproject-rtos/zephyr/tree/main/samples/bluetooth/mesh

This example includes generic on/off server and client models.
with some simple manipulation, I can toggle on and off the server model subscribed to the publishing model.
I have also tried the relay feature and it works.
However, the LPN feature is never shown up on the nrf mesh app.
I guess either the app or the zephyr does not work properly.

Thanks

[Joakim Jakobsen]

Thanks.

I don't have too much experience with that sample and what changes needs to be done.

From the documentation I linked to in my previous response;

"To make the light switch run as an LPN, set OVERLAY_CONFIG to overlay-lpn.conf when building the sample.

The configuration overlay overlay-lpn.conf enables the LPN feature, and alters certain configuration options to further lower the power consumption. To review the specific alterations, open and inspect the overlay-lpn.conf file. "

You could inspect the LPN overlay file and see what changes is needed to enable the LPN feature.

Br,
Joakim

[Omid]

Thanks Joakim, the funny thing is my LPN network including three nrf52 SDKs works although the nrf app does not show the LP feature is enabled. I am using one SDK for source, one as the friend, and one as the LP destination. I am not using the overlay config, but the LPN feature is actually working. I will try the overlay config suggestion later. Again, thanks for your help.

[Joakim Jakobsen]

Ah, I see. I think I misunderstood. I thought the LPN feature didn't show up in the app because it didn't work. 

It might be some limitation to what information is available in the application. Which OS and nRF Mesh version do you have on your phone?

Br, 
Joakim

[Omid]

Hi Joakin, I am using IOS and NRF app version is 3.2.0

[Joakim Jakobsen]

Thanks.

I'll check with our mobile developers if this is an iOS related issue.

Br,
Joakim