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!!

[Kazi Afroza Sultana]

Hello,

It looks like you are encountering the issue while trying to set the internal RC oscillator on your custom board.  When you use sysbuild with nRF5340, you need to configure the clock settings for both application and network core separately.

And yes, you found the correct way, you have to use hci_rpmsg as the network core image, not ipc_radio.

You have to create child_image inside the application folder which should look like 

# Create this directory structure:
<project_root>/child_image/hci_rpmsg.conf

Inside this hci_rpmsg.conf file, the configurations will be like these ( you did this inside sysbuild.conf) 

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC_CALIBRATION=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_500PPM=y
CONFIG_SOC_ENABLE_LFXO=n

Could you please try this and pristine build the program?

Let me know if this works.

BR

Kazi