RE: DFU and settings

Hung Bui — Fri, 23 Apr 2021 13:01:27 GMT

Hi Fabien,

The bootloader is designed so that an application update will always resign in the predefined location (right after the softdevice). This explain why when you update your setting data it doesn't work.

For your purpose, if you don't want to modify the bootloader I would suggest you can think of sending/receiving the setting data in your application and then store it to where you need.

If it's ok to modify the bootloader then you can think of either define a new type of image see dfu_fw_type_t inside dfu-cc.pb.h

Or you can re-use DFU_FW_TYPE_EXTERNAL_APPLICATION , but you define a special location that you will store the image. When an image is generated as DFU_FW_TYPE_EXTERNAL_APPLICATION (in nrfutil you use --external-app) the bootloader will only store it in the swap bank (bank 1) and won't replace the application with the new image.
So in your case, you just need to modify the bootloader so that when it receive the DFU_FW_TYPE_EXTERNAL_APPLICATION it will store the image in the data location that you selected instead of bank1 location. Doing this you don't need to modify the nrfutil or the app on the phone for the task.