On Feb 7, 9:35 UTC, "David J Taylor" wrote: > My (rather limited) understanding was that the > atom driver was simply a filter on an existing PPS signal, and therefore > you would need a driver which knew about the LPT port and could detect and > use its PPS signal. Which driver does that I don't know, as I've never > used one.
There used to be a grain of truth in what you say, but with the current code, the grain is gone. It used to be the case that drivers that implemented their own PPSAPI handling, including the NMEA driver (20), relied on code in the ATOM driver (22) to filter the PPS samples over a polling interval into a single offset. Last April, Dr. Mills relocated that code to ntp_refclock.c in new common PPSAPI handling code used by several drivers, including the Spectracom/WWVB driver, NMEA driver, ATOM driver, and to some extent, the parse drivers. The driver which supports PPS independent of any other timecode/ refclock is the ATOM driver, number 22. The PPSAPI code in 4.2.6's ATOM and NMEA drivers is essentially the same, the difference is whether it's used independently or associated with a NMEA source. Used independently, there must be at least one other source marked prefer. Cheers, Dave Hart _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
