How to change the application start address in NCS?

[Varkey]

Hi Nordic community,

How do I change the start address of an NRF54L15 application in NCS Zephyr?

I need an address other than the default 0.

I have tried adding 

CONFIG_FLASH_LOAD_OFFSET in the config and made relevant changes in the dts partition, but ended up with no change in the address.

Will I be able to start the code directly at a specific address (E.g., 0x00002000) on every reboot?

If not, what could be the best way to run an application at a specific address on reboot?

Any help is much appreciated.

[Vidar Berg]

Hello,

Execution always starts from the reset handler pointed to by the reset vector at address 0x4 after a reset. So if you want to boot an application at a different address, you must have a bootloader at address 0x0 that can branch to your application. Maybe you could say a bit more about what you are trying to achieve with this?

Best regards,

Vidar

[Varkey]

Hi Vidar,

Sorry for the delay in response.

I had managed with a bootloader, which decides which application to execute based on certain conditions.

Is the Master Boot Record (MBR) available in the nRF54L15, or anything similar to that?

I am referring to the MBR available in the nRF52833.

[Vidar Berg]

No problem, but I’m still not sure what you’re end goal is. The MBR didn't let you control the boot sequence. It either boots the bootloader, if one is present, or it booths fw image starting at 0x1000.

[Varkey]

Hey Vidar,

Let me clarify my first questions and the current status of those.

Varkey said:

How do I change the start address of an NRF54L15 application in NCS Zephyr?

I need an address other than the default 0.

I have tried adding 

CONFIG_FLASH_LOAD_OFFSET in the config and made relevant changes in the dts partition, but ended up with no change in the address.

I did it with No Sysbuild and by using the macros CONFIG_FLASH_LOAD_OFFSET and CONFIG_FLASH_LOAD_SIZE.

Varkey said:

Will I be able to start the code directly at a specific address (E.g., 0x00002000) on every reboot?

If not, what could be the best way to run an application at a specific address on reboot?

As you suggested, I need a bootloader to branch to my application.

In my case, I will have two images, one of which is an application and a bootloader, both of which can update each other.

Can I use the Nordic Secure Immutable Bootloader (NSIB) to achieve this goal in the NRF54L15 SOC using NCS 3.1.0? Is there an example project on how to use NSIB? How can I set the next image(application/bootloader) jump address in the NSIB on the next reboot? I might need to jump to the application/bootloader from NSIB from an external trigger.

[Vidar Berg]

Hi,

Please take a look at the bootloader section of our devacademy course at https://academy.nordicsemi.com/courses/nrf-connect-sdk-intermediate/lessons/lesson-9-bootloaders-and-dfu-fota/ and also this section of the SDK if you need MCUBoot to be upgradeable: https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/app_dev/bootloaders_dfu/mcuboot_nsib/bootloader_mcuboot_nsib.html#app-dfu