Custom MCUboot DFU bootloader nrf Connect

[Richard]

Hi,

We want to modify the bootloader process on MCUboot. To avoid someone having to press and hold a button the entire time on our custom boards we want as a minimum to set a pin high to ensure it doesn't turn off.

I was successfully able to try this using SYS_INIT and a custom board.c file by following this ticket  Modify the MCUboot's booting process however, the problem I've found with this method is it sets the pin high regardless of whether the unit goes through the bootloader or not - which makes sense. In some instances we want to indicate the bootloader is running by switching on an LED just as user feedback something's going on. So a potential flicker of the LED (e.g. switching it off ASAP in the main app) would be inappropriate for our devices. 

It looks therefore that the best way to achieve what we want is by modifying the bootloader and I've gone down a ticket rabbit hole through here  How to create custom MCUBOOT for DFU which ends up leading to this blog archive:  nRF Connect SDK Tutorial - Part 2 | NCS v1.3.0 

is there a more up to date and recommended way of customising the mcuboot? Our aim would be to have a file within the main project directory that handles the main functions of the boot but adds in our own "switch on this pin" code.

Thanks.

BR,
Richard

[Sigurd]

Hi,

To avoid someone having to press and hold a button the entire time on our custom boards

Could you explain this some more? Why does a use need to press and hold a button?

[Richard]

Hi Sigurd,

On most of our boards we have a soft power on that maintains the power after being physically switched on via a button. The board is therefore either on by pressing and holding the button, or on if a pin is held high.

BR,
Richard

[Sigurd]

Hi,

Maybe this mcuboot action hook could be used for your use-case:

https://github.com/nrfconnect/sdk-mcuboot/blob/v1.9.99-ncs2/boot/zephyr/Kconfig#L578

https://github.com/nrfconnect/sdk-mcuboot/blob/main/boot/bootutil/include/bootutil/mcuboot_status.h

[Richard]

That looks promising. Where does the handler for mcuboot_status_change need to be placed?

I've added it in the main project directory at the moment (which I suspected would be wrong), I'm getting this in the build log:

c:/ncs/toolchains/v2.1.2/opt/zephyr-sdk/arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/10.3.0/../../../../arm-zephyr-eabi/bin/ld.exe: app/libapp.a(loader.c.obj): in function `context_boot_go':
C:\ncs\v2.1.2\bootloader\mcuboot\boot\bootutil\src\loader.c:2112: undefined reference to `mcuboot_status_change'
collect2.exe: error: ld returned 1 exit status

I added 

CONFIG_MCUBOOT_ACTION_HOOKS=y into my mcuboot.conf file which is within a child_image folder.

[Sigurd]

Hi,

I haven't tested it, but I'm thinking that you in CMakeLists.txt in boards/arm/your_board , can add something like this:

if(CONFIG_MCUBOOT)
zephyr_library()
zephyr_library_sources(my_mcuboot_hook.c)
endif()

Then place a my_mcuboot_hook.c in boards/arm/your_board

Might need to include these:

#include "bootutil/boot_hooks.h"
#include "bootutil/mcuboot_status.h"