NRF5340 - PRE KERNEL1 timer

RE: NRF5340 - PRE KERNEL1 timer

Turbo J — Tue, 18 Feb 2025 15:06:14 GMT

It would have been a good idea to mention mcuboot in your first post...

PRE_KERNEL means running after MCUBOOT, which is its own little project that runs before everything.

If you wanted to do something at mcuboot time, you needed to modify this project. Not recommended unless you know what you are doing - it took me a while to get my custom MCUBOOT project running properly with an application (I wanted SD card support for the bootloader).

RE: NRF5340 - PRE KERNEL1 timer

Hung Bui — Tue, 18 Feb 2025 09:09:56 GMT

Hi Yo,

MCUBoot taking 1s sounds a bit strange. Could you check if you see the same issue with a simple sample in the SDK ?
How large is your application ? Boot validation can take a long time on a larger application.
You can try to turn off CONFIG_BOOT_VALIDATE_SLOT0=n to see if the boot time is reduced. See here: Boot up time of NCS application

Another option is to have something running before MCUBoot. Check here: RE: Modify the MCUboot's booting process

RE: NRF5340 - PRE KERNEL1 timer

Yog! — Mon, 17 Feb 2025 18:41:25 GMT

Hi,

The registers took from nrf5340 datasheet, and the gpio works, so it should be fine.

I saw there is a macro to register "TIMER1_IRQHandler" as a week function, so it looks like it just need to be implemented, anyways, with nrfx- i register "timer_event_handler" to this timer.

and i tried to use "IRQ_CONNECT" and enabled macro but nothing.

at the end i managed to run something with nrfx but just after pre_kernel1, which is too late so i need to use the bare metal registers to run it before any kernel or OS.

for some reason, the mcuboot takes ~1sec to boot 😞

RE: NRF5340 - PRE KERNEL1 timer

Turbo J — Sat, 15 Feb 2025 14:09:41 GMT

You might also have wrong magic numbers in your own register definitions. Checking would trigger my hourly rates - I am NOT a nordic employee.

Use the compiler macros from the NRF connect SDK. NRF_P0 should be available once you

#include <zephyr/kernel.h>

EDIT: I am a bit blind. Your interrupt handler function TIMER1_IRQHandler is not connected to the interrupt stuff yet. You would need the IRQ_CONNECT macro in order to do that.

Try putting a debug break point into that handler function in order to check.

You should have gotten an unhandled interrupt exception unless the timer1 is enabled in the dts - which means it has an interrupt handler function already.

RE: NRF5340 - PRE KERNEL1 timer

Yog! — Sat, 15 Feb 2025 13:20:13 GMT

Hi and thanks!

i got you about magic numbers, absolutely should be taken from device tree.

anyways, the led gpio actually works, i can make it turn on and off.

I want to toggle it from timer isr, but i couldnt make it work, i configure the timer but nothing happens.

the thing is that i want it to work pure hardware, before the OS starts.

maybe i missed some basic stuff, thanks for your reply!

RE: NRF5340 - PRE KERNEL1 timer

Turbo J — Sat, 15 Feb 2025 12:21:20 GMT

Pin configs are set much later in startup process, you have to set up the PIN_CNF register manually. GPIO pins have the output disabled at reset.

You should look up how to use a device tree overlay to set port/pin number instead of using a hard coded magic number.