NRF connect debugger stuck on arm reset.s

RE: NRF connect debugger stuck on arm reset.s

Einar Thorsrud — Wed, 29 Oct 2025 09:54:47 GMT

Hi,

I see. Can you share more about the board you are running on (perhaps share the schematics)? Also, which SDK version are you using? And lastly, does your firmware run on a DK (if you have that available)?

A few common pitfalls when running on custom HW is if that does not have the 32.768 kHz oscillator or DCDC inductors, and either of those are enabled. So I would start by disabling those by adding this to prj.conf or similar:

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_XTAL=n
CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC_CALIBRATION=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_500PPM=y

CONFIG_BOARD_ENABLE_DCDC=n

RE: NRF connect debugger stuck on arm reset.s

DanZ — Mon, 27 Oct 2025 21:18:09 GMT

Adding extra info:

Registers:

-exec info registers
r0 0x0 0
r1 0x0 0
r2 0x0 0
r3 0x0 0
r4 0x0 0
r5 0x0 0
r6 0x0 0
r7 0x0 0
r8 0x0 0
r9 0x0 0
r10 0x0 0
r11 0x0 0
r12 0x0 0
sp 0x20003aa0 0x20003aa0 <z_main_stack+1024>
lr 0xffffffff -1
pc 0xe6ac 0xe6ac <z_arm_reset>
xpsr 0x1000000 16777216
fpscr 0x0 0
msp 0x20003aa0 0x20003aa0 <z_main_stack+1024>
psp 0x0 0x0 <internal_rand>
primask 0x0 0
basepri 0x0 0
faultmask 0x0 0
control 0x0 0
apsr 0x0 0
epsr 0x1000000 16777216
ipsr 0x0 0
iapsr 0x0 0
eapsr 0x1000000 16777216
iepsr 0x1000000 16777216

Threads:

-exec info threads

Id Target Id Frame * 1 Thread 57005 (Unknown thread) z_arm_reset () at C:/ncs/v2.0.0/zephyr/arch/arm/core/aarch32/cortex_m\reset.S:68

-exec info fun main

All functions matching regular expression "main": File ../src/main.c: 43: void main(void); File C:/ncs/v2.0.0/zephyr/arch/arm/core/aarch32/thread.c: 519: void arch_switch_to_main_thread(struct k_thread *, char *, k_thread_entry_t); File C:/ncs/v2.0.0/zephyr/kernel/init.c: 197: static void bg_thread_main(void *, void *, void *); 348: static void switch_to_main_thread(char *); File C:/ncs/v2.0.0/zephyr/kernel/timeout.c: 183: k_ticks_t z_timeout_remaining(const struct _timeout *); File C:/ncs/v2.0.0/zephyr/kernel/work.c: 580: static void work_queue_main(void *, void *, void *);

RE: NRF connect debugger stuck on arm reset.s

DanZ — Mon, 27 Oct 2025 20:41:26 GMT

Hey,

Thanks for the reply.
The call stack is empty, just z_arm_reset().
I am expecting it to break on the enterance to main, before BT is enabled.

The code breaks in the same place, even when compiling with: CONFIG_RESET_ON_FATAL_ERROR=n

RE: NRF connect debugger stuck on arm reset.s

Einar Thorsrud — Mon, 27 Oct 2025 13:08:13 GMT

Hi,

It could be interesting to see the call stack, but could this be that the device restes due to an error as the default error handler triggers a reset? Can you test with CONFIG_RESET_ON_FATAL_ERROR=n? Also, as you mention stepping and Bluetooth, please note that the Bluetooth stack will most often trigger an assert if you step in the code or contine from a breakpoint when Bluetooth is enabled.

RE: NRF connect debugger stuck on arm reset.s

DanZ — Sat, 25 Oct 2025 22:29:34 GMT

I'll add that I'm debugging via a NRF52 DK using P20. I think the setup and the wiring itself is ok, since this does seem to work against some of the boards that I have.