On Mon, Aug 17, 2020 at 06:07:41PM +0000, Irene Kravets wrote: > Can ptp4l be used without phc2sys on a PTP slave to produce a 1PPS > signal that's synchronized to the master's 1PPS?
Yes. > If my understanding is correct, I would expect that running just > ptp4l would be sufficient to sync 1PPS signals, however, when I > tried it, the 1PPS signals were not synchronized. I thought that > phc2sys is only needed to synchronize the system clock to PHC and > that phc2sys should not be needed to synchronize 1PPS, but that's > not what I am observing. Is my understanding wrong? No, you are correct. The phc2sys program synchronizes the Linux system clock from the PHC. > When I run both ptp4l and phc2sys on the slave, the 1PPS signal is > synchronized, but there is a 2-3 usec delay between master and slave > 1PPS signal when I observe both on a scope. Why is that delay there > and is there any way to make it much smaller? I need them to be > within 20-30 nsec of each other. If the PPS signal is being produced by the PHC, then the offsets should be lower. I guess your PPS is NOT coming from the PHC? Well, I can only guess, because you did not provide any information about your hardware. Thanks, Richard _______________________________________________ Linuxptp-users mailing list Linuxptp-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-users
