On Tue, Aug 23, 2011 at 13:02, Thomas Laus <[email protected]> wrote:
> The capture / assert configuration options does
> not select reading the leading or trailing edge of a PPS pulse, NTP
> only reads timestamps to the on the leading edge and you may require
> an inverter to swap polatity for NetBSD to read and sync to your PPS
> pulse.
Actually, fudge flag2 does determine whether ntpd refclocks using the
common PPSAPI code (such as the atom/PPS, NMEA, and WWVB drivers)
request timestamps for the assert or clear transition. See
ntp_refclock.c refclock_params():
/*
* Solaris serial ports provide PPS pulse capture only on the
* assert edge. FreeBSD serial ports provide capture on the
* clear edge, while FreeBSD parallel ports provide capture
* on the assert edge. Your mileage may vary.
*/
if (mode & CLK_FLAG2)
ap->pps_params.mode = PPS_TSFMT_TSPEC | PPS_CAPTURECLEAR;
else
ap->pps_params.mode = PPS_TSFMT_TSPEC | PPS_CAPTUREASSERT;
if (time_pps_setparams(ap->handle, &ap->pps_params) < 0) {
msyslog(LOG_ERR,
"refclock_params: time_pps_setparams: %m");
return (0);
}
As the comment notes, not all PPSAPI implementations can actually
timestamp either edge. So it's not a limitation of ntpd, but of
NetBSD's timepps.h, in your case.
Cheers,
Dave Hart
_______________________________________________
questions mailing list
[email protected]
http://lists.ntp.org/listinfo/questions
