Application won't boot when bootloader and app are using 32kHz RC oscillator. When using MPSL (BLE and IEEE802.15.4 raw) or usb_cdc.

[Maarten de Kruijf]

Hi,

We're having a problem that our application will hang when using the 32 kHz RC oscillator in the mcuboot bootloader and the Zephyr application. We encountered this problem when we updated from NCS 1.5.1 to 1.8.0. 

We have looked at https://devzone.nordicsemi.com/f/nordic-q-a/81418/bug-in-ncs-v1-7-1-with-32khz-rc-oscillator-and-mcuboot-enabled and https://github.com/zephyrproject-rtos/zephyr/issues/40538 but that does not seems to fix our issue or is not included in release 1.8.0

In the supplied files is a markdown file with steps how to reproduce the problem.

What could be a temporary fix? 

What is the prospect of a permanent fix?

Best regards,

Maarten

rc_oscillator_problem_files.zip

[Hung Bui]

Hi Maarten, 

I was not able to reproduce the issue on a nRF52840 DK (with SB1 SB2 cut). 
I have tested both on your blinky example with 
west build -p -b nrf52840dk_nrf52840 -- -DDTC_OVERLAY_FILE=console.overlay && west flash

I can see the log printed out on the USB-CDC port and the LED blinking. 

Same applied for the usb-cdc example after adding 

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y

CONFIG_BOOTLOADER_MCUBOOT=y

I could see the echo worked fine. 

I attached here the merged.hex of the blinky code that you sent. Could you please try testing on your DK ? Do you have other DK boards to test ? 

4075.merged.hex