Timeout exit from the boot loader

[DX_HK]

I am developing an application that uses NCS2.8.0.

For FW updates, the nRF52833 USB ACM bootloader is enabled.

However, there are some problem.

My device has a battery but no reset button, so the application cannot start unless I reset it with mcumgr.

Since we do not want to unnecessarily expose the bootloader to users, bootloader startup cannot be used at any time.

The bootloader timeout seems to only be effective if the bootloader always starts after a reset.

CONFIG_BOOT_SERIAL_WAIT_FOR_DFU=y
CONFIG_BOOT_SERIAL_WAIT_FOR_DFU_TIMEOUT=2000

Is it possible to only enable the bootloader timeout?

Or can I exit the bootloader by other means (e.g. user switch)?

[Vidar Berg]

Hello,

Please correct me if I'm wrong, but is my understanding correct that you're fine with the bootloader always enter serial recovery mode on startup, but you prefer not to expose any mcumgr commands in the application?

Thanks,

Vidar

[DX_HK]

No, I don't want the bootloader to start during normal boot.

In other words, the bootloader will only start with
bootmode_set(BOOT_MODE_TYPE_BOOTLOADER);

[DX_HK]

After the bootloader starts, if no operations are performed for, say, one minute, is it possible to start an application?

[Vidar Berg]

CONFIG_BOOT_SERIAL_WAIT_FOR_DFU_TIMEOUT only works in conjunction with CONFIG_BOOT_SERIAL_WAIT_FOR_DFU. If you want the same timeout for other entry methods you will need to modify the bootloader.

[DX_HK]

Is there a way to exit mcuboot using a button (not the reset button)?

[Vidar Berg]

It is possible, but this is also something that will require customization of the bootloader.

[DX_HK]

The bootloader is provided by NCS.
I don't think it's that difficult to customize the code,
but if I want to customize NCS, how should I change it?

[Vidar Berg]

I would start by just making changes directly to the main.c file for the bootloader in the SDK tree /v2.8.0/bootloader/mcuboot/boot/zephyr/ to verify that your changes work. You can then decide how you want to include these changes into your project setup. 

[DX_HK]

Thank you. I have performed a test implementation and it is working properly.

This bootloader timeout feature seems more commonly needed.
This time, I customized the bootloader, but customization by general users is not a good thing.
I think such basic functions should be selectable without modifying the code.

What should we do if multiple people are developing this custom bootloader?
Specifically, there are several engineers in the company who develop using Zephyr, and the bootloader should be common, so this change should be synchronized via git (github).

For example, would it be possible for us to create a fork of NCS and use that instead of the nordic repository?

[Vidar Berg]

Possible options that come to mind:

1. Create a patch file that you apply that you and your coworkers can apply to the SDK during installation

2. Submit a PR to propose your change at https://github.com/mcu-tools/mcuboot 

3. Create a workspace application that includes a fork of the https://github.com/nrfconnect/sdk-mcuboot repository (see Forking a repository of the nRF Connect SDK).