3.22 not sending PPS to SHM

[Gary E. Miller]

Yo David!

Replies should go to the list so others can also help.

On Mon, 11 Jan 2021 13:40:42 +0000
David Taylor <david-taylor@blueyonder.co.uk> wrote:

> Thanks very much for your comments, Gary.  I didn't know of ntpshmmon
> so that sounds like the perfect tool to test with.  I'm going to
> rebuild one RPi from scratch and see what I can learn from a
> completely fresh installation.  

There is scratch, and there is scratch.  Raspbian should take a few
minutes.  Gentoo a day or two.

> I do note that on one PC I get only NTP0 lines on ntpshmmon,  

Which is normal if you have no PPS on the PC.

> and on 
> another NTP0 and NTP1 lines.  

Which is normal on s serial port or USB/Serial that also has PPS.

>  I see on your sample NTP0 and NTP2.  

Yup.  Because the "serial" port on the RasPi is not a full serial port,
so the PPS has to come from eleswhere (GPIO).

> Are these just the names of the memory segments?  

Sort of.  The "real" names are "NTP0", "NTP1", etc.  But commonly
referred to as SHM(0), SHM(1) to make their location clearer.

> What's significant
> if I only have one?  

It means you only have one time source being sent to ntpd (or chronyd)..
Which could be only serial time or only PPS time.

RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
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