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Re: [gpsd-users] gpsd loses the connection with the M8T when Raw is enab

From: Stéphane Péneau
Subject: Re: [gpsd-users] gpsd loses the connection with the M8T when Raw is enabled.
Date: Sun, 14 Apr 2019 09:57:19 +0200
User-agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1

Hi Gary!

A dead M9T?  Too bad!
I received a F9P and I finally hope to get my multiband antenna next week.

I switched the M8T refresh rate from 5 Hz to 1 Hz and I still have the checksum errors.

I will use an oscilloscope tomorrow.


Le 14/04/2019 à 01:29, Gary E. Miller a écrit :
Yo Stéphane!

On Sat, 13 Apr 2019 15:16:48 +0200
Stéphane Péneau <address@hidden> wrote:

I use a Raspberry Pi 2, with Raspbian Stretch (4.14.98) and a U-blox
neo-M8T connected on the uart and the timepulse on the gpio18.
Cool, I have similar here.  Except my M9T seems dead right now...

I need the nmea stream for a python script, and the raw stream to
postprocess the data with RTKLIB.

When only nmea is enabled, everything is fine.

But when I enabled UBX-RAWX and UBX-SFRBX, gpsd regularly loses the
connection and I don't receive any data for a few minutes.
UBX-RAWX and UBX-SFRBX is a lot of data.

Looks like your speed is 115,200, which may be a tad slow, or not:

     gpsd:INFO: SER: speed 115200, 8N1

You have a LOT of checksum errors:

gpsd:IO: UBX checksum 0x6ef7 over length 61, expecting 0x0c25 (type 0x6201)

That points to a serial port problem.

I would put an oscilloscope on it and check the voltage levels of
the serial lines, the voltage on the M8T, and that the serial line is
not saturated.

Also try a faster speed.

You neglected to say how you started gpsd.  Be sure to use the -n option.

When I start gpsd with debug enabled, I see that it retry to connect
to the uart with a different speed and I don't understand why.
Autobaud.  To stop autobaud, just set the port speed correctly before
starting gpsd.  Or just let it do its job.  Which seems like it
is working for you.

The full  log is attached with this mail
Here is the interesting part:

     gpsd:INFO: launching (Version 3.18.1)

Please try git head.  There has been a lot of work for u-blox 8 and 9
since then.  But I see nothing in your logs that git head might
affect.  YMMV.

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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