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Re: [gpsd-users] 1PPS not working with RPi 3 B+ and Stretch


From: Gary E. Miller
Subject: Re: [gpsd-users] 1PPS not working with RPi 3 B+ and Stretch
Date: Fri, 20 Jul 2018 19:42:36 -0700

Yo Chris!

On Fri, 20 Jul 2018 21:32:29 -0400
Chris Smith <address@hidden> wrote:

> Attached "gpspipe -r -n 120" output
> 
> Also, how's this for a EIA-232 spec? Admittedly, it's not the info I
> used in my initial research...
> 
> http://www.ti.com/lit/an/slla037a/slla037a.pdf

Nope, not THE spec.  Just the TI take on RS-232F.  I'll bet no TI
part is on your Dell motherboard.

And in any case, that tech note reconfirms the -3V for the low
voltage.  Which as we both agree is not what you are providing.  So, not
conformant to the spec or to the TI design note.

So we are just going round and round on settled data where you
got it wrong. 

So, once again, it may work for you, but is NOT spec conformant.  And
not conformant to that tech note.  So wrong.

> And I think this is a pretty comprensive overview of things...
> 
> http://www.wikiwand.com/en/RS-232

Once again, we're going in circles:

1. Wikipedia, by their own desire, is NEVER authoritative.

2. We already know your PPS is working, so off topic.

> address@hidden:~/gpsd $ date && pstree -paul | fgrep gpsd && ps -ef |
> grep gps && ./gpsd -V &&  sudo ./ntpshmmon

"sudo" is evil.  "sudo" is the cause of half the problems in that howto,
Just go root and stay root.  At least until it works.

"./gpsd -V" is ueseless as we do not know if that is the one you
started.

Since, you said, you installed several versions of gpsd, it is quite
possible you have multiple verions ot the binaries and libraries.

Please verify you only have one copy of gpsd parts.

When trying to prove to me that the gpsd parts match, you need to use
full paths.

Not what I asked for, and, no need to recover all that old ground.

>   |   |           |-grep,11068 -F --color=auto gpsd
>   |               `-sudo,10850,root ./gpsd -n
> -N /dev/ttyAMA0 /dev/pps0 |                   `-gpsd,10854,nobody -n
> -N /dev/ttyAMA0 /dev/pps0 |                       |-{gpsd},10855

Running gpsd in the foreground not a good idea for timing.

> ntpshmmon version 1
> #      Name Seen@                Clock                Real
>  L Prec
> 
> ...no data...

Very odd.  How about you try to start gpsd properly this time:

$ su -
# ./gpsd -n /dev/ttyAMA0 /dev/pps0
# cgps

Verify good date and time.  Then run, still as root:

# ntpshmmon.

> Again, everything's copacetic on my CentOS 7 box.

And again, not relevant.  Stick to the problem!

And just as a wild guess, is your /dev/shm mounted?

# df | fgrep shm
shm                             8146992     54740    8092252   1% /dev/shm

Lets check that your SHM works:

# gpsd -nND 4 /dev/ttyS0 |& fgrep SHM
gpsd:PROG: shmget(0x47505344, 9008, 0666) for SHM export succeeded
gpsd:PROG: shmat() for SHM export succeeded, segment 262152

Also, then dig deeper into how the PPS is looking.  Try to run this:

# gpsd -nND 4 /dev/ttyS0 |& fgrep PPS
gpsd:PROG: PPS:/dev/ttyS0 chrony socket /var/run/chrony.ttyS0.sock doesn't exist
gpsd:PROG: KPPS:/dev/ttyS0 checking /sys/devices/virtual/pps/pps0/path, 
gpsd:PROG: KPPS:/dev/ttyS0 checking /sys/devices/virtual/pps/pps1/path, 
gpsd:PROG: KPPS:/dev/ttyS0 checking /sys/devices/virtual/pps/pps2/path, 
/dev/ttyS0
gpsd:INFO: KPPS:/dev/ttyS0 RFC2783 path:/dev/pps2, fd is 7
gpsd:INFO: KPPS:/dev/ttyS0 pps_caps 0x1133
gpsd:INFO: KPPS:/dev/ttyS0 have PPS_CANWAIT
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS will be used
gpsd:PROG: PPS:/dev/ttyS0 thread launched
gpsd:INFO: PPS:/dev/ttyS0 ntpshm_link_activate: 1
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Interrupted system call
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Interrupted system call
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Interrupted system call
gpsd:PROG: KPPS:/dev/ttyS0 assert  0.000000000, sequence: 0, clear   
1532140647.000105914, sequence: 1 - using: clear
gpsd:PROG: KPPS:/dev/ttyS0 Clear cycle: 1532140647000105, duration: 
1532140647000105 @  1532140647.000105914
gpsd:PROG: PPS:/dev/ttyS0 Clear cycle: 1532140647000105, duration: 
1532140647000105 @  1532140647.000105914
gpsd:PROG: KPPS:/dev/ttyS0 assert  0.000000000, sequence: 0, clear   
1532140648.000069569, sequence: 2 - using: clear
gpsd:PROG: KPPS:/dev/ttyS0 Clear cycle:  999963, duration: 1532140648000069 @  
1532140648.000069569
gpsd:PROG: PPS:/dev/ttyS0 Clear cycle:  999963, duration:       0 @  
1532140648.000069569

That is how the PPS is supposed to look.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

            Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin

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