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Re: [gpsd-users] Communication loss with GR-701W

From: Gary E. Miller
Subject: Re: [gpsd-users] Communication loss with GR-701W
Date: Tue, 21 May 2019 10:45:38 -0700

Yo Benoît!

On Tue, 21 May 2019 18:08:11 +0200
Benoît Thébaudeau <address@hidden> wrote:

> A factory reset of the configuration did not help with this issue. It
> happened again after having plugged the module only twice following
> the configuration revert,

So not a saved config issue.

> and without gpsd having saved any
> configuration changes to NVRAM.

gpsd NEVER saves anythin to NVRAM, FLASH, etc.

> BTW, I've discovered u-center
> (, which is a great tool
> too.

Ugh.  You can't run Python, but you can run windows?

> > # ubxtool -e BINARY [hostname]  
> That worked, which confirms that the corresponding packets sent by
> gpsd were not received or interpreted by the module.

Not really.  Many other possible failure mechanisms.

> I noticed the FIXME about waiting for the ACKs in ubx_cfg_prt(), so I
> tried the following patch as a workaround, and so far it works:

Then you are overrunning the u-blox input buffer.

What serial speed are you running the GPS at?

> +    usleep(100000);
>      count = gpsd_write(session, session->msgbuf, session->msgbuflen);
> +    usleep(100000);

Which, of course, breaks a lot of other stuff...

> Unfortunately, I do not have time to investigate this issue more
> deeply.

I don't think that is required, we have long suspected serial overrun,
and your tests mostly confirm that.  The only other thing to try is
different serial port speeds to see if that has any effect.

> FYI, the ntp fudge time1 value that I got for the GR-701W using the
> peerstats-based procedure is 0.181638.

Today.  It will changed.  Always best to make sure it is noselect.
Otherwise it will cause problems.

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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