NewLine:
Why is this?
Because uboot (the very first thing run by the linux side when you power it on) has "Hit any key to stop autoboot" message. If some byte gets sent in those 5 seconds, you'll enter uboot console and never have linux started
NewLine:
Oh that is bad....means it will not be able to boot as long as the mcu does not get restarted (if the mcu sketch sends stuff over the bridge), right?
Right