Bootloader and SD DFU

[genis]

After reading the FAQ on DFU I still do not understand how the bootloader and SD DFU are performed so that a failure during the upgrade does not brick the device (see answer A, bullets 3 and 4).

My initial guess is that bootloader and SD are small enough for them to be temporaly stored in RAM. But anyway, at some point they need to be copied to flash through calls to the MBR. If a reset occurs while being copied, flash will end by having a corrupt SD or a corrupt bootloader.

Is it that bootloader and sd are always upgraded with dual-bank DFU? If so, what if I have no spare room on my flash because my application uses it all?

I've read carefully the documentation available but I could not find the answer. Please point any document that may explain that and I may have overlooked.

[bjorn-spockeli]

Hi Genis,

you are partially correct, nothing is stored in RAM, but Bootloader and SoftDevice updates are always performed with dual-bank DFU. The application will be erased prior to a SoftDevice + Bootloader update to make room for the image and you will have to update the application after the SD+BL update. This is shown on this infocenter page.

Best regards

Bjørn

[genis]

Ok I missed that when I read it. Thanks!