It's been done on FreeBSD. See:
http://lists.freebsd.org/pipermail/freebsd-arm/2013-February/004769.html
Patch is now in recent FreeBSD releases/snapshots
And yes, it's far superior to than using the GPIOs, or UARTS
There was some work done on Linux, but I'm not sure it was ever finished
or published.
All of my "Timing" Beaglebones run FreeBSD, with the exception of the
TIC stufff I wrote for the PRUSS's. As soon as the userspace bits of
that work on FreeBSD, I'll probably switch that to FreeBSD as well.
All the Best
Iain
On 21/10/14 13:33, Neil Schroeder wrote:
Andrew-
I'm actually referring to using either the eCAP function or one of the
integrated dmtimer triggers - which are, from some accounts, more accurate
than a gpio.
Google beaglebone dmtimer pps.
NS
On Mon, Oct 20, 2014 at 11:56 PM, Andrew Rodland <[email protected]>
wrote:
On Mon, Oct 20, 2014 at 10:50 PM, Neil Schroeder <[email protected]>
wrote:
The one thing that hasn't yet happened is making the beaglebone timestamp
on the linux side in a way that works for ntp.
Custom code no problem. Freebsd PPSAPI no problem. Linux, nothing there
yet.
I have been working on it but if anyone has some insight its appreciated.
It appears to support gpio class devices, with interrupts, so the
pps-gpio driver (in-tree since 3.2) should work just fine. The only
thing that's needed (other than building the driver) is a bit of code
in the board support file to register the device. Various folks have
done it for the rpi (http://ntpi.openchaos.org/pps_pi/ for example),
and I've done it for the UDOO Dual
(https://gist.github.com/arodland/518f037e4f24b1984286). The BBB is
probably about as easy.
I'm not sure if there's other hardware that lets you do better than
grabbing an interrupt, but that will get you in the microsecond range
or a bit better, anyhow.
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