It looks like it implements parsing of some received binary message types.
According to bootloader README:
0x08000000 - Custom bootloader. (Normally application code starts here.) 0x08004000 - Bootloader maintained metadata: image size and checksum. 0x08004800 - Application. Must be linked to go here.
It seems to be changed for the L412 because 64k Flash.
According to .ld files and bootloader config:
0x08002000 - Application 0x08001800 - Metadata.
Maiana has a custom bootloader, installed in addition to the STM32's usual ROM bootloader.
Toggle TX switch twice on power up to enter.
Boards have been produced with various chips in the STM32L4 series.
64kB Flash. 40kB RAM.
$PAISYS,11.9.1,4.4.1,,STM32L412,1,1*08 $PAISTN,0,,,0,0,0,0,0*11 $PAITXCFG,1,1,1,0,0*0B $PMTK011,MTKGPS*08 $PMTK010,001*2E $PMTK011,MTKGPS*08 $PMTK010,002*2D
“$PAISYS,%s,%s,%s,%s,%s,%d*”, hwRev(), FW_REV, serNum(), mcuType(),
breakoutType(), isBootloaderPresent())