[time-nuts] Raspberry Pi NTP server

[David J Taylor]

From: Matthias Welwarsky
[]
Forgive me chiming in with a recommendation: Drop the Raspberry Pi and get a
Beaglebone Black instead. It is the much better platform for timekeeping
experiments.

Firstly, it has capture-mode timers that will give much more stable 
timestamps
for the 1PPS kernel interface.

Secondly, you can drive these timers from an external clock source. That 
clock
source can be a GPSDO. That means, you can hook up the timer input clock to
the 10MHz GPSDO output and at the same time use it for timestamping the 
GPSDO
1PPS pulses. Plus, this timer can be the "wall clock" for the Linux system,
resulting in a zero-drift system time. Combine that with gpsd and you have a
stratum-1 time source.

Thirdly, the ethernet mac is on chip and it supports hardware timestamps. 
This
means, not only NTP but also PTPv2 is possible.

BR,
Matthias
===============================================

... and it has much less general support
... and it generates more RF interference
... and it costs money as the OP already has the Raspberry Pi

Neither make for "precision" sources.  I've yet to see a comparison between 
the BeagleBone and a Raspberry Pi 4.  I did make a comparison earlier which 
showed the BBB to be better, yes, but certainly not enough for me to change 
given the other factors.

Cheers,
David
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