The question of CIS and BIS modes work at the same time

[huma]

In my last question, devzone.nordicsemi.com/.../can-cis-and-bis-modes-work-at-the-same-time-or-switching-freely, I have asked that if the CIS and BIS modes can work at the same time. And i got the answer is can, and there is example show that in the V2.7.0 SDK.

But i found the example(ISO combined BIS and CIS) is only using for the common data transmissions, what i want is that the CIS and BIC modes can work at the same time for the le-audio, And i found that the nrf5340 audio application in the V2.7.0 SDK is still only can configure one mode at one time. I know that in theory, le audio can also be considered as transmitting data, but due to specific bandwidth and resource limitations, I have to confirm again whether nrf5340 can achieve le audio working in both CIS and BIS modes at same time. If it can, is there any plan to implement it into nrf5340 audio application? If it can not, does nrf54H20 can enable the two mode at the same time for the le-audio?

By the way, i also found that the nrf5340 audio application in the V2.7.0 SDK can not work well, when it started as the default headset mode, it will output these following logs.

Thank you very much and looking forward to your help!

[huma]

Hello dejans,

Thank you for your reply.

I am agree with you about the resources part. I think the resources of nRF5340 is the biggest limitation for  making CIS and BIS work at the same time.

And this is also the biggest challenge for me, If there has some chance to make these two modes can work at the same time for le-audio, i have to try to implement it. But the nRF5340 audio application is too complex at that part, CIS and BIS seem to be mutually exclusive to a large extent. I have tried to enable them at the same time, but the compilation cannot proceed properly, which means I need to spend a lot of time modifying the project. And if i start the work from the other example just like "Bluetooth: ISO combined BIS and CIS", it also means that i need to spent more time to implement the audio part.

So do you have any suggestions? Do you think the user scenarios I want is feasible in terms of resources?

If you think this worth trying, Do you have any suggestions for modifying the project?

Thank you very much and looking forward to your reply!

[dejans]

Hi,

huma said:

I am agree with you about the resources part. I think the resources of nRF5340 is the biggest limitation for  making CIS and BIS work at the same time.

Resources on nrf5340 could be a limiting factor. It can be expected that there could be problems with airtime and possible drift. The audio quality might get restricted.

huma said:

So do you have any suggestions? Do you think the user scenarios I want is feasible in terms of resources?

If you think this worth trying, Do you have any suggestions for modifying the project?

Currently, our audio project might not be a good fit for your scenario. However, there are several pointers to the modules which you can study:
- bt_le_audio_tx.c, for figuring out how to send packets
- le_audio_rx.c, for tracking how to receive packets and send to audio_datapath for decoding and play
- audio_system.c, for how to start lc3 codec, and also initialize/start roles
Afterwards, you can study iso_combined_bis_and_cis sample, try to create your own according to your scenario and find proper parameters. When you know how data flows PCM -> ENC -> transport -> DEC -> PCM, you can use API for additional audio stream features.

Best regards,
Dejan