Does the MCUMGR have a foolproof feature?

[Yoshihiro Goto]

I am learning how to use MCUMGR. I generally understand it, but I have some concerns.

- The firmware with the private key can also be overwritten. Then it will not boot.
(By the way, we call this a paperweight.)

- It is possible to write even if the model (e.g. nRF52832 and nRF52840) is different. Of course, it will not boot.

Is there any way to avoid these foolproofs?

In addition, it is not foolproof,

- I don't know how to write to slot 1. Adding -n1 options doesn't work.

Best Regards,
Yoshihiro Goto

[Amanda Hsieh]

Hi, 

The bootloader will skip the invalid image and boot the valid image in the other slot if using the dual-slot configuration. If using the recovery mode with the single-slot configuration, you could upload the correct image again. 

- I don't know how to write to slot 1. Adding -n1 options doesn't work.

Which sample are you using? Are you using external flash? Could you post the command you are using? 

The doc said:

The mcumgr image upload command may be provided optional -e -n <image> parameter that will select target image for upload; when parameter is no provided, 0 is assumed, which means “default behaviour”, and it performs upload to the “image-1”, the MCUboot secondary slot.

Try to upload without -e -n <image> parameter to see if it can work or not. 

Regards,
Amanda H.

[Yoshihiro Goto]

Hello,

My apologize, I was confusing recovery mode from mcuboot and DFU over USB. I was overwriting firmware in recovery mode.

https://academy.nordicsemi.com/courses/nrf-connect-sdk-intermediate/lessons/lesson-8-bootloaders-and-dfu-fota/topic/exercise-2-dfu-over-usb-adding-external-flash/

I followed the instructions on the above page to perform a USB DFU and was able to upload to slot 1.

Best Regards,
Yoshihiro Goto