On Tue, Sep 8, 2015 at 5:17 PM, Joachim Fabini <joachim.fab...@tuwien.ac.at> wrote: > On 08.09.2015 09:44, Gabs Ricalde wrote: >> I've been running two devices (TPLink WR703N, MR3020) for more than 2 >> years with almost no issue. Also impressed on what these devices could >> do. Does the new OpenWRT versions have the PPS driver for AR9331? I had >> to use this for Attitude Adjustment: >> https://code.google.com/p/openwrt-stratum1/ > > Thanks for the pointer, nice project. However, one side-note: the y-axis > label in the diagram shown on the google code page can't be correct - > the unit must be ms, NOT µs. > > An offset smaller than +-200ns is imho ways out of reach for such > devices, 200µs is feasible. In particular when considering the > mechanisms used according to the PpsGpioPollDriver description (100µs > interval waiting/polling). Still the accuracy is good and should be > sufficient for many tasks.
The scale is correct, if I run ppstest I get this: root@OpenWrt:~# ppstest /dev/pps0 trying PPS source "/dev/pps0" found PPS source "/dev/pps0" ok, found 1 source(s), now start fetching data... source 0 - assert 1441711928.999999999, sequence: 6248816 - clear 0.000000000, sequence: 0 source 0 - assert 1441711929.999999949, sequence: 6248817 - clear 0.000000000, sequence: 0 source 0 - assert 1441711931.000000004, sequence: 6248818 - clear 0.000000000, sequence: 0 source 0 - assert 1441711931.999999970, sequence: 6248819 - clear 0.000000000, sequence: 0 source 0 - assert 1441711932.999999929, sequence: 6248820 - clear 0.000000000, sequence: 0 source 0 - assert 1441711933.999999983, sequence: 6248821 - clear 0.000000000, sequence: 0 source 0 - assert 1441711934.999999966, sequence: 6248822 - clear 0.000000000, sequence: 0 source 0 - assert 1441711936.000000001, sequence: 6248823 - clear 0.000000000, sequence: 0 source 0 - assert 1441711936.999999960, sequence: 6248824 - clear 0.000000000, sequence: 0 source 0 - assert 1441711937.999999962, sequence: 6248825 - clear 0.000000000, sequence: 0 The 100 us interval is only for determining the coarse time. > Joachim > _______________________________________________ > questions mailing list > questions@lists.ntp.org > http://lists.ntp.org/listinfo/questions _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions