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

[weamx]

Hello,

I encountered a similar issue, which took me a couple of days to resolve. While your situation might not be identical, the solution that worked for me was to ensure that the network core configuration matched the application core configuration. Specifically (in your case), just add the following lines to the network core configuration:

CONFIG_SOC_ENABLE_LFXO=n
CONFIG_CLOCK_CONTROL_NRF_K32SRC_SYNTH=y

Also you can check this bluetooth-won-t-connect thread for more information 

Hope this helps!