to become idle; it actually doesn't matter as the chip takes care of this for us. It would also spin endlessly in certain circumstances during shutdown. While I'm here, (finally) add code to allow sending BREAK characters.
interrupt time. This was the cause of the 'mmu fault' panics seen by several people, as the Tx interrupt is at a higher priority that spltty().
Communications Controller. This is still a work in progress, but it is functional enough to be usable.