Right, that's why I brought up the GPS sentences. You'd need a small micro to read the chronodot registers and output formatted serial, the 1pps can go directly to the PC.
On Fri, May 17, 2013 at 3:24 PM, mike cook <[email protected]> wrote: > > > > Le 17 mai 2013 à 22:52, Eric Williams a écrit : > > > That's based on my experience, but I did go in and tweaked the offset > > register in mine over the course of a month or so. I think it has gotten > > off 3-4 seconds in a year. > > > > I have found the same, BUT, they are not a solution to the issue. The > reason is that the OS doesn't read the RTC after initial boot sequence, > when the system clock is initialised. All clock references are to the > system clock from there on until orderly shutdown when it is updated from > the system clock value. > So it will give an accurate time at boot, but the system clock stability > will predominate from there. My Raspberry Pi which has one of these > installed has a 40ppm clock drift even though the RTC does better. I need > NTP to get correct it. > > > > > On Fri, May 17, 2013 at 1:33 PM, Tom Van Baak <[email protected]> > wrote: > > > >>> Even something as simple as a Chronodot will hold to a few seconds a > >> year. > >> > >> Eric, > >> > >> Are you sure? My understanding is that the Chronodot is based on the > >> DS3231. Quoting http://datasheets.maxim-ic.com/en/ds/DS3231.pdf we > read: > >> > >> The DS3231 is a serial RTC driven by a temperature compensated 32kHz > >> crystal oscillator. The TCXO provides a stable and accurate reference > >> clock, and maintains the RTC to within ±2 minutes per year accuracy from > >> -40°C to +85°C. > >> > >> /tvb > >> > >> _______________________________________________ > >> time-nuts mailing list -- [email protected] > >> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > >> > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
