Re: [gpsd-dev] Detecting Raspberry Pi Hat & PPS

[Frank Nicholas]

On May 5, 2016, at 9:08 PM, Gary E. Miller <address@hidden> wrote:

Yo Frank!

On Thu, 5 May 2016 20:49:11 -0400
Frank Nicholas <address@hidden> wrote:

From my Pi2:
dev2-rpi ~ # gpsd -nND 9 /dev/ttyAMA0 |& fgrep PPS
gpsd:PROG: PPS:/dev/ttyAMA0 chrony socket /var/run/chrony.ttyAMA0.sock doesn't exist
gpsd:WARN: KPPS:/dev/pps0 kernel PPS unavailable, PPS accuracy will suffer

Ouch.  gpsd tried to open the /dev/pps0 because you had
the /dev/ttyAMA0.  Good so far, but...

We have seen this before, the solution unclear.  Look in: ppsthread.c.
Basically init_kernel_pps() failed.  Either it could not open(/dev/pps0)
or it could not time_pps_create() that file handle.

Probably not the former, since you did not see:
   "KPPS:%s running as %d/%d, cannot open %s: %s\n",

Probably not the laster, since you did not see:
   "KPPS:%s time_pps_create(%d) failed: %s\n"

I am blind to what other failure path is in there without an error
log.

What other type of error log can I supply?  Or did you mean you don’t see any “errors” in the output provided & aren’t sure where else to look?

PPS device is automatically created:
crw-rw---- 1 root tty  244, 0 Dec 31  1969 /dev/pps0

I assume 'ppstest /dev/pps0' works fine?

dev2-rpi ~ # 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 1462496956.685301211, sequence: 12636 - clear  0.000000000, sequence: 0

source 0 - assert 1462496957.685304128, sequence: 12637 - clear  0.000000000, sequence: 0

source 0 - assert 1462496958.685307044, sequence: 12638 - clear  0.000000000, sequence: 0

source 0 - assert 1462496959.685309075, sequence: 12639 - clear  0.000000000, sequence: 0

source 0 - assert 1462496960.685314752, sequence: 12640 - clear  0.000000000, sequence: 0

source 0 - assert 1462496961.685318032, sequence: 12641 - clear  0.000000000, sequence: 0

source 0 - assert 1462496962.685324490, sequence: 12642 - clear  0.000000000, sequence: 0

You might try perms 666 to rule out a permissions problem.  That has
not helped before.

I had it at 666, before letting UDEV reset it to 660 (on reboot).  I’ve tried both, with same results.

Stock Raspberry Pi kernel from:
git clone --depth 1 https://github.com/raspberrypi/firmware.git

pps_gpio                2655  0
pps_core                6779  1 pps_gpio

Those are the two you need.  Thus the /dev/pps0.

I’m logging for the evening.  I’ll take a look again tomorrow.

Thanks,

Frank