Over-the-air DFU requires two uploads (SDK12.0.0 + S132 3.0.0)

[Jarmo]

We made a version of bootloader_secure for our own purposes. The problem is now that application must be uploaded twice into the device (nRF52) before it really gets updated. I guess it is because of dual banking and for some reason, the bank is not changed when application is uploaded.

So I am asking if somebody knows where in the bootloader_secure is the code fragment that makes the bank changing, and what possibly goes wrong there? On the other hand, I don't find mentions of dual banking from the code (quickly peeking), so could there be some other reason for that behavior?

[Hung Bui]

The bank swapping is done inside nrf_dfu_app_continue().

What do you have after :INFO:num transports: 1 ? Would the device reset and you are back to main ? You may want to post the full log. You may also add a break point ad check why the new application is not consider valid app (nrf_dfu_app_is_valid()) and the bootloader stay in bootloader mode instead of the application.

You can also record the two logs, and compare what make the difference between the first and the second update.

Have you tried to get the hex dump and check if the image is actually copied into bank 1 (or bank 0 if you are using single bank) .