[time-nuts] more of a time distribution question
hmurray at megapathdsl.net
Thu Mar 30 16:43:34 EDT 2017
jimlux at earthlink.net said:
> I've got a bunch (a pack?) of beaglebones that are connected via ethernet
> (wired) and I want them to be (roughly) synchronized.
> Running NTP (in some flavor) would be the obvious approach, but I'm in an
> environment where there's no "outside" connectivity.. Could I make one of
> the beaglebones be the NTP server, and the others be the clients?
Yes. Search for orphan mode. I've never tried it. Let e know if you can't
figure out how to make it work and I'll use that as an excuse to learn more.
> (I've seen some "add a GPS to a Rpi to make a NTP server" projects, and I
> could probably leverage that)
That should work. I haven't found a GPS with PPS for the beaglebone. What
level of accuracy do you want? If you only need 100 ms or so, then a normal
junk GPS (no PPS) on USB should work.
There is at least one GPS+PPS over USB. The GPS breakout board plus FTDI USB
2.0 breakout with a few wires gives you PPS with improved accuracy. (Not
great, just 8x better than PPS over old/slow USB.) I got mine from Sparkfun.
> I've also got a laptop (a mac, as it happens).. what's involved in making
> *that* be a NTP server (e.g. the Mac might get its time from a NTP server
> at some higher stratum, and then it propagates it down).
That should work too. I don't know much about the Mac environment. If it's
running a normal-enough ntpd it is already a server and you don't have to do
anything. If not, you will have to build/install your own and/or poke holes
in the firewall rules.
These are my opinions. I hate spam.
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