Sets the bootloader mode and returns the status after the requested
mode change was instigated.
You can change from bootloader mode to firmware mode and vice versa. A change
from bootloader mode to firmware mode will only take place if the entry function,
device identifier and CRC are present and correct.
This function is used by Brick Viewer during flashing. It should not be
necessary to call it in a normal user program.
The following meanings are defined for the parameters of this function: