I once worked with on a project that needed specialized timing in relation to high speed (well, 38.4k) RS422 communications. I don't remember all of the details, it's been decades. I remember one of the engineers came up with a super clever way to trigger the time measurement and actually measure it. Rather than using a UART he bit-banged the communications and actually used the serial stream for timing (meaning the one's and zero's). It worked amazingly well. If I remember correctly that was a Z80 processor with limited resources.