We have an application using a Kinetis K70 that requires a refresh of all flash storage. This refresh is executed every 10 years in a maintenance mode without the main application running. The flash refresh includes a bootloader area. We were considering using duplicate copies of the bootloader and the flash swap capability to protect the device during maintenance. Our application requires much more than half the flash size so we cannot simply dedicate blocks. We were hoping to just maintain a bootloader at 0x0000 offset of both block halves. The bootloader would detect a block swapped boot which would indicate a problem and do a targeted rewrite of its own image to the alternate block. Can we erase and then write the non-active block sector by sector without a full block erase when swapped?