Hal Murray via devel writes: > One is the use the PTP style time-stamping available on many modern Ethernet > interfaces. Does anybody know how that works? API? I assume there is a > counter in the Ethernet hardware. How does that counter get converted into a > time stamp?
Yes, it's a hardware counter and it runs with the local clock of the interface (you'll typically find a 25MHz quartz next to the ethernet chip, although for gigabit ethernet that clock is obviously internally multiplied with a PLL). The timestamp can be recorded in a register, attached to the transmit or receive frame memory or even added to the outgoing packet. Highlevel API would be PTP for Linux (ptp4l) or linuxptl, kernel API: https://www.kernel.org/doc/Documentation/ptp/ptp.txt Also, Dan drown is again ahead of you… :-) https://blog.dan.drown.org/apu2-ntp-server-2/ > Their other approach is to collect much more data. There are a couple of > good > slides showing the offset with an empty band in the middle. I'm not going to look at that stuff on YouTube… any link to oldfashioned non-multimedia? Regards, Achim. -- +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+ SD adaptation for Waldorf Blofeld V1.15B11: http://Synth.Stromeko.net/Downloads.html#WaldorfSDada _______________________________________________ devel mailing list devel@ntpsec.org http://lists.ntpsec.org/mailman/listinfo/devel
