nRF5340 Audio DK - LE Audio CIS example not works

[ashokr.com]

Hi Team,

we are using two nRF5340 Audio DK kits to test LE Audio CIS example (unicast client & server).

kit1 nRF5340 Audio DK - act as gateway ( connected to PC/shared usb audio )

kit2 nRF5340 Audio DK - act as headset  ( earphone)

after power ON kit1 , I did not see the LED1 (blue) blinking.

I see following logs printing security failure messages on client side. kindly help on getting CIS mode working on two audio kits.

GW [00:00:00.269,348] <inf> board_version: Compatible board/HW version found: 1.0.0
GW [00:00:00.301,696] <inf> fw_info:
nRF5340 Audio nRF5340 Audio DK cpuapp
NCS base version: 3.0.2
Cmake run : Thu Jun 19 18:16:28 2025
GW [00:00:00.301,696] <inf> fw_info: ------- DEBUG BUILD -------
GW [00:00:00.301,696] <inf> fw_info: Compiled for GATEWAY device
GW [00:00:00.343,536] <inf> bt_mgmt_ctlr_cfg: Controller: SoftDevice: Version 6.0 (0x0e), Revision 8435
GW [00:00:00.343,719] <inf> bt_mgmt: Local identity addr: F4:47:0D:BD:D3:16 (random)
GW [00:00:00.343,902] <inf> audio_usb: Ready for USB host to send/receive.
GW [00:00:00.346,496] <inf> bt_mgmt_scan: Local addr: 50:29:D3:9C:DB:AA (random). May time out. Updates not printed
GW [00:00:00.346,527] <inf> bt_mgmt_scan: Scanning successfully started
GW [00:00:00.410,675] <inf> bt_mgmt_scan: Creating connection to device: 47:88:13:0E:EC:8E (random)
GW [00:00:00.511,535] <inf> bt_mgmt: Connected: 47:88:13:0E:EC:8E (random)
GW [00:00:00.511,566] <inf> main: Connection event. Num connections: 1
GW [00:00:00.553,802] <wrn> bt_mgmt: Security failed: level 1 err 9
GW [00:00:00.553,802] <wrn> bt_mgmt: Failed to disconnect -128
GW [00:00:00.554,046] <inf> bt_mgmt: Disconnected: 47:88:13:0E:EC:8E (random), reason 0x05
GW [00:00:00.554,077] <inf> main: Disconnection event. Num connections: 0
GW [00:00:00.554,077] <wrn> unicast_client: Unknown connection disconnected
GW [00:00:00.554,962] <inf> bt_mgmt_scan: Local addr: 50:29:D3:9C:DB:AA (random). May time out. Updates not printed
GW [00:00:00.554,992] <inf> bt_mgmt_scan: Scanning successfully started
GW [00:00:01.845,275] <inf> bt_mgmt_scan: Creating connection to device: 77:1B:D1:1C:67:E8 (random)
GW [00:00:01.950,073] <inf> bt_mgmt: Connected: 77:1B:D1:1C:67:E8 (random)
GW [00:00:01.950,103] <inf> main: Connection event. Num connections: 1
GW [00:00:01.992,279] <wrn> bt_mgmt: Security failed: level 1 err 9
GW [00:00:01.992,279] <wrn> bt_mgmt: Failed to disconnect -128
GW [00:00:01.992,523] <inf> bt_mgmt: Disconnected: 77:1B:D1:1C:67:E8 (random), reason 0x05
GW [00:00:01.992,553] <inf> main: Disconnection event. Num connections: 0
GW [00:00:01.992,584] <wrn> unicast_client: Unknown connection disconnected
GW [00:00:01.993,499] <inf> bt_mgmt_scan: Local addr: 50:29:D3:9C:DB:AA (random). May time out. Updates not printed
GW [00:00:01.993,499] <inf> bt_mgmt_scan: Scanning successfully started
GW [00:00:03.284,637] <inf> bt_mgmt_scan: Creating connection to device: 4D:8F:CE:E2:1A:E7 (random)
GW [00:00:03.393,066] <inf> bt_mgmt: Connected: 4D:8F:CE:E2:1A:E7 (random)
GW [00:00:03.393,096] <inf> main: Connection event. Num connections: 1
GW [00:00:03.435,272] <wrn> bt_mgmt: Security failed: level 1 err 9
GW [00:00:03.435,272] <wrn> bt_mgmt: Failed to disconnect -128
GW [00:00:03.435,546] <inf> bt_mgmt: Disconnected: 4D:8F:CE:E2:1A:E7 (random), reason 0x05
GW [00:00:03.435,577] <inf> main: Disconnection event. Num connections: 0
GW [00:00:03.435,577] <wrn> unicast_client: Unknown connection disconnected
GW [00:00:03.436,492] <inf> bt_mgmt_scan: Local addr: 50:29:D3:9C:DB:AA (random). May time out. Updates not printed

 

Thanks

Ashok R

[Edvin]

Hello Ashok,

Could it be that some old bonding data is stored in one device, and not the other? Try erasing both boards, and re-program them with the applications and see if the behavior changes. 

To erase the board, you can do this in VS Code by clicking the 3 dots next to your board in the "Connected Devices" tab, and select "Erase board"

Or you can use nrfjprog:

nrfjprog --eraseall

Or you can use nrfutil:

nrfutil device erase

Best regards,

Edvin

[ashokr.com]

Hi Edvin,

Thanks it works and solved the connection issue but now new problem i'm facing is , Audio stream received on the sever (audio jack) breaks, not clear, strucks. On TX side I see below log warnings.

when usb audio is playing (laptop) uart logs prints are not working, could be memory buffer issue?   

GW [00:02:06.965,057] <inf> unicast_client: LEFT source stream configured
GW [00:02:06.965,118] <inf> le_audio: LC3 codec config for source:
GW [00:02:06.965,118] <inf> le_audio: Frequency: 24000 Hz
GW [00:02:06.965,118] <inf> le_audio: Duration: 10000 us
GW [00:02:06.965,118] <inf> le_audio: Channel allocation: 0x1
GW [00:02:06.965,148] <inf> le_audio: Octets per frame: 60 (48000 bps)
GW [00:02:06.965,148] <inf> le_audio: Frames per SDU: 1
GW [00:02:07.724,884] <inf> unicast_client: Stream 0x20012170 started
GW [00:02:07.726,715] <inf> audio_usb: USB RX first data received.
GW [00:02:07.759,582] <wrn> audio_usb: USB TX underrun. Num: 2801
GW [00:02:07.859,588] <wrn> audio_usb: USB TX underrun. Num: 2901
GW [00:02:07.905,487] <inf> unicast_client: Stream 0x20012270 started
GW [00:02:07.915,588] <inf> audio_usb: USB TX first data sent.
GW [00:02:08.189,697] <wrn> audio_usb: Wrong length: 183
GW [00:02:21.125,000] <wrn> audio_usb: USB TX underrun. Num: 3001
GW [00:02:21.555,023] <wrn> audio_usb: USB TX underrun. Num: 3101
GW [00:02:22.005,035] <wrn> audio_usb: USB TX underrun. Num: 3201
GW [00:02:22.455,047] <wrn> audio_usb: USB TX underrun.

Thanks

Ashok r

[Edvin]

Hello Ashok,

This is likely a CPU load issue. You are using 24kHz The USB interface only supports 48kHz, which means you have two encoders + sample rate converter + USB transfer + other system overhead. You can try analyze this with the built-in Zephyr CPU load monitor. It may be that the load is so high that nothing is printed. Try to run with 48kHz, and see if that is more smotth.

Also, you can try to add CONFIG_BT_AUDIO_PREF_SAMPLE_RATE_16KHZ=y, and see if that helps.

Best regards,

Edvin

[ashokr.com]

Hi Edvin,

The example code is untouched, so you meant by default the sample is configured to 24khz?

anyway as per your last sugegstion , I added   into both server & client overlay file. Now Audio works fine.

I have few questions,

1. I see the audio bitrate at 32kbps for 16Khz sampling frequency. Is there limitation on nordic chip? for sampling at 48KHZ. Due to usb ?

2. What if I want to play music from SD card , can I achieve maximum bitrate? if yes what is the maximum bitrate we can get?

Thanks

Ashok R

[Edvin]

Just add one of these to your sample's prj.conf:

CONFIG_BT_AUDIO_PREF_SAMPLE_RATE_16KHZ=y

or 

CONFIG_BT_AUDIO_PREF_SAMPLE_RATE_48KHZ=y

[ashokr.com]

Yes , 48KHZ works fine. not sure why volume control does not works. for vol-up/vol-down 

GW [00:00:01.963,195] <inf> le_audio: LC3 codec config for source:
GW [00:00:01.963,226] <inf> le_audio: Frequency: 48000 Hz
GW [00:00:01.963,226] <inf> le_audio: Duration: 10000 us
GW [00:00:01.963,226] <inf> le_audio: Channel allocation: 0x1
GW [00:00:01.963,226] <inf> le_audio: Octets per frame: 120 (96000 bps)
GW [00:00:01.963,226] <inf> le_audio: Frames per SDU: 1