nrf5340_audio:How to hear sound in the right headset?

[liuzong]

Hi,

I'm running some transceiver tests to look at extended broadcast and ISO transfer modes. I am using  nrf5340_audio_dk and ncs V2.6.0 to run nrf5340_audio application. I have saw this in here. First I can hear in my left ear. Then I press the reset key while holding down the 1 key according to the instructions. The log shows that the current receiving end is right device.

After testing, I could determine that the receiver of headset had indeed changed from BIG1 to BIG2. But the truth is I can still only hear in my left ear. What else do you need to do if you want to hear the sound in the right ear of the headset?

Best wishes，

Liuzong.

[Hieu]

Hi Liuzong,

Referring to the nRF5340 Audio DK's schematic, it seems that the HW Codec there is a CS47L63, which only has a mono differential headphone driver. The HW Codec then is only connected to the tip part of the 3.5mm socket. Therefore, you only get sounds on your left ear.

You would need to find a different method to confirm that the audio sent is actually the right channel. You could perhaps use a stream that only has sound on the right channel?

Hieu

[liuzong]

Hi,

Although I didn't try to send a right-channel-only stream, I did two experiments: sent a stream that contains both the right and left channels, sent a stream that contains only a right-channel stream . It turns out that when I send a stream that contains both the right and left channels, no matter whether the receiver is the right device or the left device, the sound can only be heard in the left ear. When sending a stream with only the left channel, only the left device can hear the sound in the left ear, and the right device cannot hear the sound.I will show the results of my experiment in a table.

Can this result explain the problem? Is it still necessary for me to try to send streams that contain only the right channel?

Best wishes,

Liuzong.

[Hieu]

Hi Liuzong,

Yes, that result should explain things. This is how I reason it:

Sound file	Config	Output	Hear in L ear	Hear in R ear
		If the file has sound on the currently configured channel, there will be output	As long as there is an output, there will be sound	There cannot be sound
L&R	L	Yes	Yes	No
L&R	R	Yes	Yes	No
L-only	L	Yes	Yes	No
L-only	R	No	No	No

Best regards,

Hieu

[liuzong]

Hi,

I seem to see what you mean. You're talking about a mono headphone driver at the hardware level, which means if there's an output, it's in the left ear.

[ace.johnny]

Yes, this is correct. The CS47L63 codec is a mono device, and while it can transceive multiple channels, it is hardwired to only the Left output on the Audio DK's TRS headphone connector.

It is possible, however, to mix multiple channels into a single mono signal so that they can all be heard in the Left output simultaneously, but this requires editing the /src/drivers/cs47l63_reg_conf.h file which contains the register settings that configure the CS47L63 during operation.