Bonding issue when using synthesized clock (BLE on NRF5340)

[thomas_hexploy]

Hi,

I cannot bond to NRF5340DK running the `peripheral_ancs_client` sample if external oscillator configuration is disabled (thus using synthesized from HFCLK).

Environment

• OS: Linux
• Toolchain zephyr-sdk-0.16.8
• NRF5340DK
• NCS 2.7 (sdk-nrf v2.7.0 and zephyr v3.6.99-ncs2)

To Reproduce

In the sample `samples/bluetooth/peripheral_ancs_client`, run the following command:

west build -b nrf5340dk/nrf5340/cpuapp -d build_bond
west flash -d build_bond

Then using `nrf connect` on Android, try to bond to the device `ANCS`
=> YOU CAN BOND to the device

In the sample `samples/bluetooth/peripheral_ancs_client`, edit `prj.conf` by adding the following configurations:

CONFIG_SOC_ENABLE_LFXO=n
CONFIG_CLOCK_CONTROL_NRF_K32SRC_SYNTH=y

Then run the following command:

west build -b nrf5340dk/nrf5340/cpuapp -d build_bug
west flash -d build_bug

Then using `nrf connect` on Android, try to bond to the device `ANCS` (Don't forget to remove the old bonding)
=> YOU CANNOT BOND to the device

Expected behavior

You should be able to bond in both clock configuration.

Impact

I can't bond to a custom board (NRF5340) which does not have an external clock.

Do you have any knowledge of this issue and how to fix this ?

Thank you

[Susheel Nuguru]

I can reproduce this. 

Actually you need to set this config in both cores also in child_image\hci_ipc.conf file.

But still it does not work. We have had issues using synth clock in older SDKs but we thought we fixed it. It seems like the issues are still there. i will have to spend more time on this to investigate. Will be back to you when I have more info or have heard some insights from the experts in the softdevice team,

[thomas_hexploy]

Hello,

Do you have any news ?

Thank you.

[Susheel Nuguru]

Thomas, 

Unfortunately no, I might have to include some hardware experts into this. This might take some time. Will be back to you when I have some insights.