Sorry if this is a dup. I had accidentally left the « SPAM » prefix on my first reply.
> Le 17 nov. 2016 à 00:24, Jay Grizzard <[email protected]> a écrit : > > So there's been a lot of discussion going around on how to do GPS foo on > pcengines.ch's apu2 hardware, but there's one question I haven't seen > discussed ... which I'm now going to discuss. Or at least ask about. > > I can't find a public datasheet for the actual processor in these (a AMD > GX-412TC SOC), but looking at datasheets for similar AMD chips, this SOC > seems to use a single 48MHz external crystal from which all the other system > clocks are derived (save for the 32.768kHz RTC). The principle should be applicable…. BUT you had better look closely at the schematics. There are some very low voltages in there. > On the apu2, this crystal is easily accessible (at least as easy as anything > SMD is). Can anyone think of a reason that it wouldn't be feasible to replace > this crystal with an external reference, à la the widely known clockblock + > Soekris net4501 hack (but with 64x the RAM)? I figure the higher frequency > might make it a bit trickier to get the signal to the board intact, but is > there any other good reason this wouldn't work? > > The CPU itself is four cores (no hyperthreading), so I'm figuring dedicate > one core to PPS handling (should give really low-jitter interrupt handling), > maybe one to ntpd, and combined with that precision reference, a pretty nice > NTP/PTP server should pop out the other side. The ethernet on the apu2 even > does hardware timestamping. > > Can anyone think of a reason this wouldn't work, before I break out the > rework gear? > > -j > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. "The power of accurate observation is commonly called cynicism by those who have not got it. » George Bernard Shaw _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
