BLE DFU Dual-Bank : Is the copy process, which follows the update process, safe?

RE: BLE DFU Dual-Bank : Is the copy process, which follows the update process, safe?

Xavier Waselle — Wed, 17 Apr 2019 13:17:27 GMT

The documentation didn't help me because it does not explain in details the copy process but I got my answer after looking in the code in image_copy().

When processing the copy, the bootloader divides the new app in pages and copies them one by one and save the store progress in flash on every successful chunk write.

RE: BLE DFU Dual-Bank : Is the copy process, which follows the update process, safe?

Andy — Wed, 17 Apr 2019 12:58:53 GMT

I'm not sure if I understand what your question is. It doesn't matter if the new firmware is smaller or bigger, what matters is if the new firmware fits in bank 1.

All of this is pretty well documented: Take a look here.

RE: BLE DFU Dual-Bank : Is the copy process, which follows the update process, safe?

Xavier Waselle — Wed, 17 Apr 2019 12:46:07 GMT

Ok but is it always the case if the size of new firmware image is bigger than the previous one?

I mean how is it proceed exactly because, as far as I know, we will copy the beginning of the new application over all the old application but the old bank 0 will not fit to the new application. Am I right? So, where will be copied the end of the new application image ? Over the beginning of the new one already copied ? If it's the case, how the bootloader can know it ?

RE: BLE DFU Dual-Bank : Is the copy process, which follows the update process, safe?

Andy — Thu, 11 Apr 2019 11:31:48 GMT

The bootloader still knows that there is a valid application in bank 1. Bank 1 isn't "cleared" until the application has been copied to bank 0 successfully, i.e. if the copy process fails due to reset or whatever, the bootloader will try to copy the application again on the next boot.