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Re: Sending commands to device while gpsd is running
From: |
Gary E. Miller |
Subject: |
Re: Sending commands to device while gpsd is running |
Date: |
Thu, 30 Dec 2021 11:01:30 -0800 |
Yo Filip!
On Thu, 30 Dec 2021 12:53:51 +0100
Filip Kubicz <filip@kubicz.engineer> wrote:
> I have a LC29D GNSS module that talks over UART with NMEA sentences.
> Receiving part is easy, gpsd parses the UART data and I can read the
> SKY and TPV in my client program.
Ah, the Quectel part. I would only call it "sorta NMEA". It has many
firmware bugs.
> However, I also need to send some commands over UART to configure it
> and then feed it with the information it needs (e.g. vehicle wheel
> ticks).
Normal.
> So far I assumed that the correct way to send such commands is with
> gpsctl -x "$COMMAND". But I see it behaves in a strange way, possibly
> trying to re-activate the device:
You are skipping a lot of details. What version gpsd? How are you
starting gpsd? Are you using the "-n" option? Was gpsd running when you
did the below?
> # gpsctl -x "$COMMAND" -D 5 /dev/ttyGPS0
Looks like you forgot the "-n" option to gpsd? What is in $COMMAND?
> When I just send the command over UART, the command succeeds and the
> device sends back $COMMANDACKOK*16
Which, of course, is invalid NMEA... We can deal with that "querk"
later.
> What would be the best way to send a command to a device while gpsd
> is running?
Besst depends a lot on what language you prefer. gpsctl works, or you
can code up a bit of Python, C, etc. The protocol is simple.
> The commands are NMEA-like text. The commands are
> independent from the daemon operation.
Yeah. "NMEA like". Just enough like NMEA to confuse things. A lot.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
gem@rellim.com Tel:+1 541 382 8588
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