[ntp:questions] like a kid with a new toy (PPS jitter)

Dave Hart davehart at gmail.com
Thu Feb 19 02:52:35 UTC 2009

On Feb 10, 12:58 pm, Chris <givemeafckingacctyoudou... at gmail.com>
> On Feb 8, 7:40 pm, Dave Hart <daveh... at gmail.com> wrote:
> > Well, a modified serial driver that would timestamp CD transitions
> > would be ideal and would give better results than I'm getting.  That's
> > not really practical unless you can start with Microsoft's existing
> > serial.sys code (it may be in theDDK, I don't know).
> Interesting, short-term I may look at that as a solution. I don't
> necessarily need to feed a single pin to multiple computers. Only one
> of the Windows machines is critical, I could sync off that if I needed
> to.
> While I only have Windows 2003DDKinstalled at the moment, they do
> include a complete serial device driver source project.
> I've only done very minor Windows driver programming, but I may try to
> download the newestDDKand give it a whirl.
> // This bit is the delta data carrier detect.  It is used to indicate
> // that the data carrier bit (in this register) has *changed*
> // since this register was last read by the CPU.
> //
> #define SERIAL_MSR_DDCD     0x08
> and
>  if (ModemStatus & (SERIAL_MSR_DCTS |
>                            SERIAL_MSR_DDSR |
>                            SERIAL_MSR_TERI |
>                            SERIAL_MSR_DDCD)) {
> I think the change would/could be done in modmflow.c or isr.c, but I'd
> really have to do some reading to get comfortable with driver
> programming. I'm not really sure how'd I'd signal an event to the ATOM
> driver (perhaps through DeviceIoCtrl?)-

Take a look at http://davehart.net/ntp/refclock/serialpps-20090219.zip

There's a .patch file you can use to build it yourself instead of
using the binary in there.

Dave Hart

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