[chrony-dev] Sending time over serial cable and firewire

[Håkan Johansson <f96hajo@xxxxxxxxxxx>]

Two programs, serial_ntpshm and ieee1394_ntpshm, to send and receive time 
stamps over a serial null-modem line or firewire bus are available at

http://fy.chalmers.se/~f96hajo/serial_ntpshm/serial_ntpshm_20110108.tar.gz

The serial transmission is with RTS/CTS and DTR/DTS, with the time of the 
latched signals transmitted in cleartext.  The receiving end does 
time-limited polling.  For firewire the bus cycle timer is used, with the 
transmitter broadcasting local measurements of it.  (See attached README 
for more details.)  Accuracy for both seems to be a few us or better.

For firewire, I suspect that the unsolicited direct broadcasting on a 
fixed isochronous channel is a bit 'impolite', perhaps there is a better 
way?

Sorry for the cross-posting, I imagine the topic (of PPS and such) to be 
of interest to some readers on all.  (Or suggestions on how to abuse a 
firewire bus less.)

Cheers,
Håkan