[ntp:questions] Atheros AR9331 w/GPS + PPS

Joachim Fabini Joachim.Fabini at tuwien.ac.at
Tue Sep 8 09:17:04 UTC 2015

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.


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