The BootROM code initiates the boot sequence with the default 4-byte
address octal output fast read command code
and the BootROM searches for a valid boot header. If a valid boot header is not
found, the BootROM attempts to load the image using the 4-byte alternate addressing
read command code
13h. If a valid boot header is
still not detected, the basic read command
tried. If the boot attempt is unsuccessful after the third command, the BootROM
increments the MultiBoot register
read address offset by 32 KB and tries the OSPI command sequence again to locate a
valid boot header. If the OSPI boot mode search limit is reached without a
successful boot, the RCU goes into lockdown and the ERROR_OUT pin is set.
The image search limit for each boot mode is listed in Boot Search Limit.