nrf5340 Internal RC Oscillator and NET core

[Loubear]

I have a project where we did not populate the external oscillator for our custom board which has an nrf5340 on it. I did most of my BLE testing on the nrf5340 devkit and everything worked. As I've been bringing up the nrf5340 on our custom board I had to add a few extra lines to the build config to enable the internal oscillator as mentioned in other posts on the forums which I found:

# Use the internal RC oscillator, not the external crystal which is not populated on our custom boards
CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_XTAL=n
CONFIG_CLOCK_CONTROL_NRF_K32SRC_500PPM=y
CONFIG_SOC_ENABLE_LFXO=n

Now everything else on the board is working fine but when I try to use BLE upon calling bt_enable() I always get:

[00:00:03.305,419] <err> bt_hci_driver: Endpoint binding failed with -11
[00:00:03.305,450] <err> bt_hci_core: HCI driver open failed (-11)

I found a very similar issue here: https://devzone.nordicsemi.com/f/nordic-q-a/113492/nrf5340-internal-rc-oscillator
One difference is I am now using sysbuild, so in order to make a custom config for the NET core I created the directory <project root>/sysbuild/ipc_radio.conf which contains the above config parameters. I am able to check the autoconf.h file for both the APP and NET cores and they both have CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC set to 1. So does this mean this is probably not a clock problem? I was under the impression that "ipc_radio" was the correct image for the NET core in the nrf5340, as opposed to the "hci_rpmsg" image used on the nrf52832 for example. Is there a different image I'm supposed to be using here? 

I am using NCS v2.8.0

Let me know if there's any more info I can provide to help figure out what might be going wrong. Thank you!!

[MadM]

Using ipc_radio is correct I guess.

In my case this issue was fixed by using the synthesized clock for the appcore and add it to the configuration of the app/mcuboot and using the RC oscillator for the netcore/b0n. Make sure to set the corresponding clock configuration for every image.

Best regards,

Marcel

[Loubear]

Marcel,

Thank you for the suggestion. I just tried doing this (and also double checked the clock settings using "west build -t menuconfig" for both app and net builds) and I still get the same error as above. Too bad :(

Thank you,
Louis

[Loubear]

Update: It appears that "ipc_radio" was the incorrect image to use for the net core. Instead I needed to use "hci_ipc" as the image. To do this I had to change my sysbuild.conf to:

# These settings were how I used the ipc_radio image, which didn't work
#SB_CONFIG_NETCORE_RPC_HOST=y
#SB_CONFIG_NETCORE_IPC_RADIO_BT_RPC=y
#SB_CONFIG_NETCORE_IPC_RADIO=y
#SB_CONFIG_NETCORE_IPC_RADIO_BT_HCI_IPC=n

# Set this flag to use hci_ipc image
SB_CONFIG_NETCORE_HCI_IPC=y

It was exceedingly hard for me to elucidate which of these images to use given the stratification of information on this topic (and maybe because the migration to sysbuild is fairly new)... But in the future where can I find more information about the nrf5340 so I can know more information about these images? This link provided some insight: https://docs.nordicsemi.com/bundle/ncs-2.5.2/page/nrf/device_guides/working_with_nrf/nrf53/nrf5340.html#bluetooth_low_energy but it didn't fully define what all the different potential images are that I can see in sysconfig. Any additional documentation here would be greatly appreciated.

Thank you,
Louis