[time-nuts] Serial or other simple protocols for exchanging time

[Mark Sims]

I would use the NMEA ZDA message.   An (easily fixed) issue with Tom's suggestion is the message does not start with a unique character... that can cause issues with syncing to the message (syncing to the end of the previous message has its own issues).   Ideally a time message should start/end with unique characters and always be the same length long.

Lady Heather does not use a 1PPS input, but has code to read the time encoded in whatever message it uses to drive the display and display time.  That code adjusts the message time for any offset between the time in the message and the actual time the message arrives (Heather uses the time-of-arrival of the last byte in the time message).   The time offset correction is receiver dependent (it can also be affected by the operating system and serial port/USB interface).    Heather uses a default, receiver dependent, time offset or the use can specify the offset (they can be positive or negative) and also has a command for measuring it (provided the OS clock is accurate).