[ntp:questions] Re: 1pps signal,20us width

rtxo gnu at wraith.sf.ca.us
Mon Nov 15 21:07:13 UTC 2004

Fei Wu wrote:

> I tried not to stretch the PPS pulse and feed it into
> RS232 port ( my pc like server ). I got the following
> error:
>  refclock_atom: time_pps_kcbind failed: Operation not
> supported.

This seems like your kernel is not an RFC2783 (ppsapi)
capable system. Linux needs the "PPSKit" patch, and
freebsd 4.x should support ppsapi.


> Does the error confirms that the pulse is too short
> for my machine?

No, it sounds like your kernel is the problem.
Also, you should make sure that the TTL signal has a
proper level converter to the rs232 signal levels, for
best compatibility with pc motherboards. An MC1488 will
work best. A MAX232 will also work, but adds a minimum
of 1.5 microseconds latency.


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