Please watch also, that you should avoid running half destroyed code.

E.g. one way can be, that all remote received data was temporary stored inside a EEPROM e.g. AT24C512. And only if it was finished, the custom bootloader make several tests, e.g. CRC testing, comparing some secret keys to be sure, that it contain a valid application.

And only then the EEPROM was copied into the internal Flash.

If your application need only 32 kB, you can also store the previous running version into the EEPROM. Then after the next power on cycle the custom bootloader await a special key sequence to mark, that the new version works right. Otherwise it restores the last running version on the next power on reset.


Peter