MCUBOOT Serial recovery not started on soft reboot

RE: MCUBOOT Serial recovery not started on soft reboot

lincoln-lu — Fri, 31 Oct 2025 02:20:52 GMT

UweRohrs

You can try the Retention System with boot mode, it support soft reboot. see the link below:

https://docs.nordicsemi.com/bundle/ncs-2.5.0/page/zephyr/services/retention/index.html

https://devzone.nordicsemi.com/f/nordic-q-a/113138/mcuboot-won-t-boot-into-serial-recovery-mode-by-using-retained-memory

I happen to be working on this too, and it works fine on my side.

RE: MCUBOOT Serial recovery not started on soft reboot

UweRohrs — Fri, 10 Oct 2025 07:19:08 GMT

I think I can answer my own question: upon reboot, it will only enter serial recovery if the elected GPIO is active and !io_boot_skip_serial_recovery(). If we dig down into io_boot_skip_serial_recovery() we see that it will only return false on 1. power on reset or 2. brown-out reset or 3. reset pin. So, as it stands, a soft-reset or watchdog reset will cause it to bypass serial recovery. Why this was designed so is a mystery to me at the moment.

static inline bool io_boot_skip_serial_recovery()

{

uint32_t rr = nrfx_reset_reason_get();

return !(rr == 0 || (rr & NRFX_RESET_REASON_RESETPIN_MASK));

}

RE: MCUBOOT Serial recovery not started on soft reboot

PjGlasso — Thu, 09 Oct 2025 14:57:52 GMT

Hi there,

So I'm interested in this topic as well. Does the GPIO in question need to be part of the RTC or GRTC group ? could it be that GPIO is not?

Shot in the Dark but hope it gets us an answer from the Vikings :-)

GL :-) PJ :v: