nRF5340 Audio - 3 streams broadcasting

RE: nRF5340 Audio - 3 streams broadcasting

Priyanka — Fri, 21 Mar 2025 10:03:54 GMT

Hi,

So the host device is some other chip, in your case, right? The problem with that is that you will then have to fix the synchronization of the streams yourself. The end-to-end latency would also increase, though that might be fine or not depending on the source of the audio.

It is possible though, but we don't have any samples for this.

-Priyanka

RE: nRF5340 Audio - 3 streams broadcasting

Nambiar — Thu, 20 Mar 2025 06:08:29 GMT

Thanks Priyanka, are there any application which can allow me just use the NRF5340 as Controller and port the application to another host processor (or some pointers in that direction) .

RE: nRF5340 Audio - 3 streams broadcasting

Priyanka — Wed, 19 Mar 2025 21:52:19 GMT

Hi,

I will discuss this with few experts and get back to you.

-Priyanka

RE: nRF5340 Audio - 3 streams broadcasting

Nambiar — Thu, 13 Mar 2025 08:46:04 GMT

Sorry I meant raw frames to transfer and do LC3 encoding in the Host Device .

RE: nRF5340 Audio - 3 streams broadcasting

Priyanka — Thu, 13 Mar 2025 08:44:03 GMT

I don't think that is also a good idea. That would lead to a much too high bit rate. The sole reason for having the codec there is to reduce bitrate.

-Priyanka

RE: nRF5340 Audio - 3 streams broadcasting

Nambiar — Tue, 11 Mar 2025 15:08:05 GMT

So the only possible way would be to use a Softdevice and use NRF5340 as only the controller and let it receive the raw PCM encoded packet (3 streams) .

RE: nRF5340 Audio - 3 streams broadcasting

Priyanka — Mon, 10 Mar 2025 09:17:56 GMT

Hi Sainath,

The problem with the CPU processing time is not with fetching the data, but with encoding it. It doesn't matter if there is 2 streams from USB and 2 from I2S, it will still require about 120% CPU to encode them (~30% per channel). Also, the USB takes 20% + CPU as well. So I would say it is quite difficult.

-Priyanka

RE: nRF5340 Audio - 3 streams broadcasting

Nambiar — Mon, 10 Mar 2025 04:10:43 GMT

Thanks for the response , awaiting the feedback.

RE: nRF5340 Audio - 3 streams broadcasting

Priyanka — Thu, 06 Mar 2025 13:41:30 GMT

Hi Sainath,

Apologies for the delay. The main issue is the CPU power. Encoding each stream takes ~30 % CPU, so as of now due to limitations, we support only two streams. But regarding using USB & I2S at the same time, I have inquired internally and will get back to you.

-Priyanka

RE: nRF5340 Audio - 3 streams broadcasting

Nambiar — Mon, 24 Feb 2025 16:38:10 GMT

Yes but I was thinking to use both USB & I2S at the same time then in that case I am getting at least 4 streams at once . That is possible right ?

What you meant is I cant increase the USB endpoint to 3 , to take in 3 mono audio channels, ?

RE: nRF5340 Audio - 3 streams broadcasting

Priyanka — Mon, 24 Feb 2025 09:33:12 GMT

Hi Sainath,

[quote user="Nambiar"]After reading through the hardware schematics , looks like the Headphones (Audio Out ) port cannot be used.[/quote]

That's right. You can use this only for Audio out.

Yes, you should be able to use USB and I2S simultaneously. But please note that the current USB implementation only has 2 (stereo) endpoints. So as of now, using USB for an additional third input is not an option.

-Priyanka

RE: nRF5340 Audio - 3 streams broadcasting

Nambiar — Thu, 20 Feb 2025 03:10:47 GMT

After reading through the hardware schematics , looks like the Headphones (Audio Out ) port cannot be used.
From the CS47L63 datasheet , its mentioned that it has 4 analog microphone (DMIC) inputs, can the team suggest the requisite pins on CS47L63 which is on the Audio DK board to provide the input ?
Or any other suggestion that can be used , can both USB and I2S be used simulataneously?