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

From: Chris Smith
Subject: Re: [gpsd-users] 1PPS not working with RPi 3 B+ and Stretch
Date: Sun, 22 Jul 2018 13:56:09 -0400

Hey Gary,

As a hobby project for a rainy day, from home, I am trying to set up a +/- 1uS NTP server on a Raspberry Pi 3 B+. That said, I have determined that NTPd alone, without GPSd, is capable of this and sufficient for doing what I am trying to without the use of the NTPD/GPSD SHM driver.

My testing is being done on a freshly imaged SD card.

So tell ya what, I think I'm done with this, whatever this is.

I feel you're misrepresenting the information that I am presenting in my e-mails and I don't feel that you're the best person for me to be talking to about what I'm trying to accomplish.

I administer a software testing lab, professionally, and I know what I'm doing. I work with embedded systems and I've been working with Linux since kernel 2.2. Your excuses keep piling up and to be quite frank, I don't feel you're responding to me in good faith and I've had enough of your needless browbeating.

I can accomplish what I am attempting to without Raspbian and without GPSd. I am currently in my initial stages of bench-marking my newly customized design.

I want your subscribers to know that there are very simple alternatives out there that can allow them to have a very precise (+/- 5uS) NTP server on their Raspberry Pi 3 B+ device with 1PPS, without GPSD. 

Take a look at the CentOS 7 ARMv7HL project.

Despite this initial release occuring when the RPi was a 2, things still appear to work quite well with RPi 3 boards.

So long, and thanks for all the fish.


On Sun, Jul 22, 2018 at 1:26 PM, Gary E. Miller <address@hidden> wrote:
Yo Chris!

On Sat, 21 Jul 2018 10:19:45 -0400
Chris Smith <address@hidden> wrote:

> I think the best way to see SHM usage is "ipcs"...

I disagree, but in you case it shows serious problems on your end.

> from a fresh boot, and before starting gpsd 3.18~dev
> address@hidden:~/gpsd $ sudo ipcs -m
> ------ Shared Memory Segments --------
> key        shmid      owner      perms      bytes      nattch
> status 0x00000000 163840     pi         600        524288
> 2          dest 0x00000000 196609     pi         600
> 393216     2          dest 0x00000000 262146     pi
> 600        524288     2          dest

The email corrupted it, but notice the owner is 'pi' when it should be root!
And nattach is 2.  Which should only happen when gpsd AND ntpd are both
running.  That does not match your description at all.

> after starting gpsd 3.18~dev

And nothing changed!  Which means what happend is not what you think.

> and after stopping gpsd 3.18~dev

And nothing changed!  Which means what happend is not what you think.

Clearly this has gotten way from you.  I suggest you start over with a
fresh SD card.

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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