Yo Mike! On Wed, 4 May 2016 08:58:48 -0400 Mike <bellyac...@gmail.com> wrote:
> > As the pps-gpio module is in April 2016 it has a flaw. It catches
> > only one edge of the PPS. You have a 50/50 chance you are seeing the
> > trailing edge rather than the leading edge (which is the actual top
> > of second). A patch to fix this has been submitted to the Linux
> > kernel maintainers but not merged.
> I've tried to figure out just how one determines exactly which edge
> is being seen.
> I'm at a loss on this one with software. Using ppstest shows me
> atypical output
Yup, beacuse the kernel module is broken and you only see one edge.
There is a patch to fix it, but we can't get it upstreamed.
> from nearly every example I'm seen online. What is the definetive
> way to determine this?
Best, use an oscilloscope. Good enough, is get a USB GPS with PPS and
compare the two PPS edges.
> The GPS device I'm using isn't a hat. In the past I've had it
> working with gpsd and ntp classic. I haven't a clue which edge is
> actually being seen though.
ppstest tells you which edges you are, or are not, seeing.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com Tel:+1 541 382 8588
pgplfs8vscnUJ.pgp
Description: OpenPGP digital signature
_______________________________________________ devel mailing list devel@ntpsec.org http://lists.ntpsec.org/mailman/listinfo/devel
