logging

[Hal Murray]

> Also the PLL goes up and offsets rise. (just like before)

Another way to maybe learn something.

Can you grab a copy of
  http://users.megapathdsl.net/~hmurray/time-nuts/60Hz/60Hz.py

It's a hack to measure line frequency using the PPS capture logic.  The idea 
is to turn that inside out and use it to measure the CPU frequency by watching 
a known-good PPS.

You may have to change the assert to clear - ntpd disables the one it isn't 
using.

If you stop ntpd, nobody should change the drift.  You can use ntptime -f 0 to 
clear it.

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You don't actually need the program.  It's just what I use to log stuff so I 
can feed it to gnuplot.

You can get the data with:
  cat /sys/class/pps/pps0/assert
It will show something like:
  1555283247.999730528#84947
The number after the # is the number of pulses.  The number before is the time 
stamp of the last pulse.


-- 
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