NR5340 AUDIO DK Microphone

[O_Hndfrd99]

Hello, I have several development-related questions about the microphone functionality of the NRF5340 AUDIO DK in headset mode:

1. Is it possible to configure the device as a microphone-only LE Audio headset using the available configurations?
2. How can I integrate and use a custom I2S microphone, such as the Adafruit ICS43434 MEMS, with the NRF5340 AUDIO DK?
3. Can the "Line In" input be used as a microphone input while in headset mode? If so, what code modifications would be necessary to enable this functionality?
4. I have the device successfully connected to a Google Pixel 9, and it works perfectly for general audio, but I am unable to use the microphone as an LE Audio input while simultaneously outputting Bluetooth audio to another pair of headphones. Is there a way to achieve this?
5. Ultimately, I aim to create a high-quality microphone solution using the NRF5340 AUDIO DK. What would be the best approach to accomplish this?

Any guidance or recommendations would be greatly appreciated!

[Hieu]

Hi cyw,

It is mentioned in the Configuring page under the overall documentation that I link. In particular, here: Configuring the nRF5340 Audio applications.

[Hieu]

Hi O_Hndfrd99,

I have been looking into the nRF5340 Audio application source code and understood its setup a little more. I believe that if you enable CONFIG_STREAM_BIDIRECTIONAL, you should be able to start using the microphone. Could you please try this and let me know if it works?

What I haven't been sure of is whether it can be just a microphone or not. I can tell right away that the nRF5340 Audio application doesn't support this case by design. However, the building blocks are there, from the bidirectional support, so I think it should be possible.

From what I have seen, I also think that the code modification shouldn't be too hard but also isn't trivial.

I am trying to be more certain of both the code and the specs before asking for a review from our developers. It's here that the lack of a LE Audio enabled smartphone has made it a bit difficult for me.

I will continue looking into it and keep you updated.

By the way, are you familiar with the nRF Connect SDK environment yet? If not, you might want to look this online course: nRF Connect SDK Fundamentals. It unfortunately isn't designed for the Audio DK though...

[O_Hndfrd99]

Hello Hieu,

The PDM is functioning for me in bidirectional mode. I will try to modify the code and configure the device as a microphone-only audio device. However, upon further consideration, would it be possible to set it up as a ‘BIS’ ‘Source’ device, effectively acting as an Auracast transmitter?

Yes, I believe a mobile device would need direct support for LE Audio and Android 13 or higher. Thank you for sharing the link to the online course and the updates.

[Hieu]

Hi O_Hndfrd99,

I am glad to hear that you have the PDM mic working in bidirectional mode.

I got information from our developer that while our stack can support setting up a microphone device, currently Android unfortunately only support headset peers for LE Audio, and microphones aren't supported yet. Thus, the closest we can do right now is what you already have working, a headset with bidirectional audio stream.

Shall we put a pause on this until Android supports LE Audio microphones?