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 Martijn and Maarten, 

I have reproduced the issue here and have reported it to our team. They are looking into the issue, I will keep you updated. 

[Hung Bui]

Just a quick update: 
We found that the issue was due to MCUboot doesn't clean up the clock before jumping to the application. 
The easy fix is https://github.com/nrfconnect/sdk-mcuboot/commit/7efbda6a58ac619506c0db2fc8ff16bec9620836

But in your case it may not be possible as you can't update the MCUboot. So we will need to find a way to stop the LFCLK and HFCLK before starting the clock in the application. Will let you know when we have a solution. 

[Hung Bui]

Hi guys,

Good news, we have a workaround. 
By adding the following code in main.c the clock stopping function will be executed before the kernel and can stop the clock from MCUBoot after that the application can start and use the clock source of its own. 

static int stop_clocks()
{ 	nrf_clock_int_disable(NRF_CLOCK, 0xFFFFFFFF);
    nrf_clock_task_trigger(NRF_CLOCK, NRF_CLOCK_TASK_LFCLKSTOP);
    nrf_clock_task_trigger(NRF_CLOCK, NRF_CLOCK_TASK_HFCLKSTOP);
	while (nrf_clock_lf_is_running(NRF_CLOCK));
	return 0;
}
SYS_INIT(stop_clocks, PRE_KERNEL_1, 0);

[Maarten de Kruijf]

Hi Hung,

Thanks for all the help so far, I have verified that the work around works for the devkit example. We will go and implement the work around in our application. I needed to adapt the example code to take a const device struct* as parameter: 

static int stop_clocks(const struct device* dev)
{
    nrf_clock_int_disable(NRF_CLOCK, 0xFFFFFFFF);
    nrf_clock_task_trigger(NRF_CLOCK, NRF_CLOCK_TASK_LFCLKSTOP);
    nrf_clock_task_trigger(NRF_CLOCK, NRF_CLOCK_TASK_HFCLKSTOP);
    while (nrf_clock_lf_is_running(NRF_CLOCK))
        ;
    return 0;
}
SYS_INIT(stop_clocks, PRE_KERNEL_1, 0);

If we have any followup questions we will post them.

Regards,
Maarten

[fafeyto]

These solutions didn't work for me. Do you have any other ideas?