Integrate NUS into BLE Audio code

[Dekel]

Hi,

I'm working with nRF5340 Audio DK.

I'm able to successfully run the audio example in BIS mode (with gateway and headset devices), and also to run the Peripheral UART Bluetooth example separately on my DK.

My goal is to open another BT connection, in parallel to the audio broadcast on my gateway device, to which I can connect with the nRF Toolbox App.

Is it possible? If so, which BT controller should be used? How should proj.conf should look like? What other configurations are required?

I've noticed that the UART example code uses adv.c for advertising, while the audio example code uses bt_mgmt.c.

Thank you,

Dekel

[Dekel]

Thanks Karl.

I'll mention that I encountered the "multiple advertising sets" example code, which seems like a good direction to follow. It's not completely strightforward to me, but I've made some progress. I'll keep you updated.

Thanks,

Dekel

[Karl Ylvisaker]

Hello again, Dekel

In the past thread debugging in VSC was not supported by the LE Audio controller, but now that we have ISO support for the SoftDevice Controller there should be no issue using all the tools available in the nRF Connect VSC extension to work with the application, so long as you make sure that you are using the SoftDevice Controller.
I am however having some troubles verifying that all the functionality works as expected, but I suspect that this is due to some recent changes I've made to my development setup, and so I'll keep looking into that.

Dekel said:

I'll mention that I encountered the "multiple advertising sets" example code, which seems like a good direction to follow. It's not completely strightforward to me, but I've made some progress. I'll keep you updated.

Which functionality from the 'multiple advertising sets' example code will you be merging into the nRF5340 LE Audio reference application? Please do not hesitate to ask if you should encounter any issues or questions while working with this! :) 

Best regards,
Karl

[EchoCharlieWhiskey]

I've been following this with interest and the multiple advertising sets was quite helpful as a hint for adding NUS to LE Audio.

I'm starting with nrf/application/nrf5340_audio (2.5.1 SDK). I want to add NUS to make a Zephyr console to my audio application (headset).

I can get the console on NUS from nrf/samples/bluetooth/shell_bt_nus. Standalone, that works with nrf/scripts/shell/bt_nus_shell.py.

I've merged shell_bt_nus into nrf5340_audio, adding CONFIG_SHELL_BT_NUS=y and  CONFIG_BT_MAX_CONN=2 into my prj.conf then modifying bt_mgmt.c's connect to call shell_bt_nus_enable (and disconnect to call disable).

However, the bt_nus_shell.py python script expects the NUS to be part of the scan response of the advertisement. (As do the other NUS tools.)

It looks like the nrf5340_audio starts the advertisement via bt_mgmt_adc.c's bt_mgmt_adv_start(...) in streamctrl_unicast_server.c. I don't see how to modify that to add NUS to this.

Anyway, looking at nrf/samples/bluetooth/multiple_adv_sets, I can see how two advertisements are being created with different data. I haven't gotten it working with NUS yet but it seems like I need to send a additional advertisements and include the NUS data as scan response? Probably  in bt_mgmt_adv.c'advertising_process()?

Or is there a simpler way?

(I did look at the older iso_peripheral_example but that code looks very different than the current LE audio applications, I couldn't see how to fit it in.)

It also seems like the Zephyr Settings API is being used to set the name from CONFIG_BT_DEVICE_NAME (and possibly other advertisement settings). I haven't explored that much. I know that is where the name comes from (commit_settings calls bt_set_name) but I couldn't see a way to add the NUS scan response in that code. 

Finally, I too would like step-through debugging with VSC. The buildprog.py script is super handy getting going but now that I'm digging into development on my headset features, I want to focus on that code, including stepping through my algorithms. 

Thank you both, Karl and Dekel, it has been really useful to read this thread. I think Dekel and I are headed in the same direction which is why we have such similar needs and questions. I hope I've represented Dekel's concerns in my summary. 

Best wishes,
ECW

[Dekel]

Karl Ylvisaker said:

so long as you make sure that you are using the SoftDevice Controller.

How can I configure that?

Karl Ylvisaker said:

Which functionality from the 'multiple advertising sets' example code will you be merging into the nRF5340 LE Audio reference application?

The connectable advertisement functionality. I would like to have it in parallel to LE Audio.

EchoCharlieWhiskey said:

Thank you both, Karl and Dekel, it has been really useful to read this thread.

I'm glad to hear that! thank you for contributing, it really seems that we are headed in the same direction.

EchoCharlieWhiskey said:

It looks like the nrf5340_audio starts the advertisement via bt_mgmt_adc.c's bt_mgmt_adv_start(...) in streamctrl_unicast_server.c. I don't see how to modify that to add NUS to this.

I encountered the same issue. The NUS seems to be deeply rooted within the SDK.

I'll share that at this point I'm able to find both LE Audio broadcast and my customized connectable advertisement with nRF Connect Mobile (with my iPhone). In parallel to audio receiving with another DK (as headset), I'm able to connect to my customized advertisement in an unstable way - seems that my phone has to be in constant connecting retries and only then the DK should be powered ON, and that sometimes works only after 4-5 tries. Bottom line, I've established an ACL connection in parallel to LE Audio broadcasting and I'm able to read basic data from the MCU (e.g. model number and manufacturer). I don't have much clue about how to integrate a bidirectional communication platform in order to send data from the app to the MCU. I would appreciate ideas about that.

[Karl Ylvisaker]

Hello,

Thank you both for your patience with this.

EchoCharlieWhiskey said:

However, the bt_nus_shell.py python script expects the NUS to be part of the scan response of the advertisement. (As do the other NUS tools.)

It looks like the nrf5340_audio starts the advertisement via bt_mgmt_adc.c's bt_mgmt_adv_start(...) in streamctrl_unicast_server.c. I don't see how to modify that to add NUS to this.

Anyway, looking at nrf/samples/bluetooth/multiple_adv_sets, I can see how two advertisements are being created with different data. I haven't gotten it working with NUS yet but it seems like I need to send a additional advertisements and include the NUS data as scan response? Probably  in bt_mgmt_adv.c'advertising_process()?

Or is there a simpler way?

You can add the NUS UUID to the scan reponse data by populating the second to last parameter in the extended advertising creation call, or you can modify the filter parameters of the NUS central devices to connect to the name (or other data) advertised by your device.

Dekel said:

How can I configure that?

To use buildprog.py, we can add the command --ctlr="SDC" parameter to switch to the SDC controller.
E.g.,
$ python buildprog.py -c both -b debug -d both -p --pristine--ctlr="SDC"

To use west instead, you can add -DCONFIG_BT_LL_ACS_NRF53=n
E.g.,
$ west build -b nrf5340_audio_dk_nrf5340_cpuapp -d build_headset -p -- -DCONFIG_AUDIO_DEV=1 -DCONFIG_BT_LL_ACS_NRF53=n; west flash --build-dir=build_headset

Dekel said:

I'm able to connect to my customized advertisement in an unstable way - seems that my phone has to be in constant connecting retries and only then the DK should be powered ON, and that sometimes works only after 4-5 tries. Bottom line, I've established an ACL connection in parallel to LE Audio broadcasting and I'm able to read basic data from the MCU (e.g. model number and manufacturer). I don't have much clue about how to integrate a bidirectional communication platform in order to send data from the app to the MCU. I would appreciate ideas about that.

Does this mean that you have got NUS up and running on your headset device alongside the ISO functionality, so that you are able to see and interact with the NUS service when connecting to the peripheral advertisement that is running alongside the ISO functionality?
If so, could you share the logs from your peripheral device when it fails those 4-5 times before achieving a stable connection?
If nothing stands out in the logs we will need to get a sniffer trace of the communication when you attempt to connect to the peripheral's advertisements - are you familiar with using the nRF Sniffer tool?

Best regards,
Karl