Hello,
We are currently evaluating BLE Gateway (CIS, BIS) development using the nRF5340 Audio DK.
We would like to ask whether bidirectional CIS streaming is officially supported when using the USB audio source.
In the documentation below, we found a statement mentioning CPU load concerns for bidirectional streaming when USB audio source is used:
Nordic Semiconductor Documentation
"The audio source selection affects the firmware architecture and available features. USB audio source is limited to unidirectional streams due to CPU load considerations, while I2S supports bidirectional communication."
Could you please explain in more detail what kind of CPU load limitations or concerns are being referred to?
Also, are there any plans to improve or address these limitations in future software and/or hardware updates?
Currently, we have tested a bidirectional CIS stream configuration using two nRF5340 Audio DK boards configured as:
- CIS Gateway (client)
- CIS Headset (server)
The test results showed normal operation:
- Gateway: outputs a 1 kHz tone
- Headset: speaker-to-microphone loopback
- Gateway: records and confirms the received 1 kHz tone
We are currently using nRF Connect SDK v3.2.4.
We have additionally ordered one more nRF5340 Audio DK and plan to test a configuration with:
- 1 CIS Gateway (client)
- 2 CIS Headsets (servers)
Additionally, the Headset board currently uses the microphone as the audio input source.
Is it possible to configure the audio input source as a 3.5 mm line input instead?
We would like to perform a loopback test using 3.5 mm output and 3.5 mm input.
Thank you.