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 final application should always be copied starting from MAIN_APPLICATION_START_ADDR ( right after the softdevice) regardless it was updated using dual bank or single bank. Please have a look here with attention to "DFU flash operations for a dual-bank application update" and "DFU flash operations for a single-bank application update"