nrf5340 audio occurred audio interruption when connected to RTT

[LandyWang]

Hello,

I am using nrf5340 audio sample with the custom board. The nRF Connect SDK version I used is v3.4.0.

I added the following settings to prj.conf so that the custom board would work.

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC_CALIBRATION=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_SYNTH=y

I burned the BIS TX program to a custom board, and the following log appeared.

GW [00:01:22.299,621] <inf> bt_le_audio_tx: Data provided too fast. May happen for sync USB. time_diff_us:  14753 (not in range: 14700 - 3000)
GW [00:01:26.349,670] <inf> bt_le_audio_tx: Data provided too fast. May happen for sync USB. time_diff_us:  14705 (not in range: 14700 - 3000)
GW [00:01:30.299,621] <inf> bt_le_audio_tx: Data provided too fast. May happen for sync USB. time_diff_us:  14735 (not in range: 14700 - 3000)
GW [00:01:34.439,514] <inf> bt_le_audio_tx: Data provided too fast. May happen for sync USB. time_diff_us:  14842 (not in range: 14700 - 3000)
GW [00:01:38.369,506] <inf> bt_le_audio_tx: Data provided too fast. May happen for sync USB. time_diff_us:  14832 (not in range: 14700 - 3000)

At this point, the BIS RX output at the receiving end exhibits intermittent audio output.

When I connect to RTT to view the log, the BIS Rx audio completely cuts out, which seems to be due to a sync loss.

What methods can I use to improve this problem?

[Turbo J]

You never want  CONFIG_CLOCK_CONTROL_NRF_K32SRC_SYNTH=y when BTLE is enabled, ever. Its not a supported config.

[LandyWang]

Thank you for your reply.

My custom board doesn't have a soldered 32.768 kHz external crystal oscillator. It only works when CONFIG_CLOCK_CONTROL_NRF_K32SRC_SYNTH is enabled.

I didn't encounter this problem when developing with nRF Connect SDK version v2.2.0 using the same configuration.

Now, even after adjusting prj.conf to only have CONFIG_CLOCK_CONTROL_NRF_K32SRC_SYNTH=y, I still experience audio interruptions after connecting to the RTT.

[Turbo J]

Check DTS. Newer SDK version have all of this clocking stuff moved into the device tree files.

The synth RTC has too much jitter for reliable BTLE operation AFAIK. No idea why the RC oscillator won't work for you, its supposed to work with calibration and temperature compensation enabled.

[LandyWang]

After disabling CONFIG_CLOCK_CONTROL_NRF_K32SRC_SYNTH and adding other settings to ipc_radio\prj.conf, the program works on the custom board.

It seems the previous failure was due to the net core not being configured for the RC oscillator.

Now that it's configured correctly, the audio interruption issue is resolved.

Thank you for your assistance.