[time-nuts] TEC party file format?

Hal Murray hmurray at megapathdsl.net
Wed Jun 29 20:27:26 UTC 2011


bg at lysator.liu.se said:
> It can be done entirely from user space as well.

> /* wait till a serial port status change interrupt is generated */
>       if (ioctl(fd, TIOCMIWAIT, TIOCM_CD | TIOCM_CTS | TIOCM_DSR)!=0)

Yup.  gpsd uses it.  As far as I know, it's only available on Linux.  I can't 
find it on FreeBSD or NetBSD.  Does anybody know if Windows supports it?

The advantage is that it doesn't need PPS support, but that's in modern Linux 
kernels.

The disadvantage is that there is more code between the interrupt and 
grabbing the time stamp and hence more opportunity for jitter.  (A constant 
delay is not a problem.  That can be subtracted out if it matters, but for 
tracking 60 Hz a constant offset doesn't matter.)


-- 
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