Re: COEX GPS (model UBX-M8030 IC) on Raspberry Pi 4 Model B 2018 connection issues

[Gary E. Miller]

Yo Aranza!

On Tue, 13 Jul 2021 12:48:50 -0700
Aranza Shaccid Leon <leon18@pnw.edu> wrote:

> I'm having some difficulty trying to connect my GPS to work with the
> gpsd program. I have a COEX GPS (module based on UBX-M8030 IC) which
> I did find a similar version named BN-880 (engine M8030-KT) was
> compatible with gpsd version 3.14.

Anythin based on M8030 should work fine.  It has USB built in, no
serial/usb converter.

> I currently have gpsd version 3.17

3.17 is 4 years out of data.  Their are a lot of u-blox updates to gpsd
since then.

> and the GPS is connected both to a
> flight controller of a drone that has a UART port connection between
> the two. The flight controller (Pixracer) is connected to the
> Raspberroy Pi (RPi) via a USB cable.

That could be a problem.  Managing two different streams from one
M8030 is not something 3.17 cared about.

> On the SD card of the Raspberry I've only installed gpsd and gpsd
> clients (along with necessary programs for the drones flight) and I'm
> operating on Windows using PuTTY as an SSH window.

What Distro on the Pi?  I hipe somthing 64-bit with a recent kernel.

> I've been following a guide that instructs how to connect these two,
> but due to my GPS setup I've been having slight difficulties. Most
> instructions I've searched for have a connection between the GPS to
> the RPi (GPIO pins) so this may be the cause of difficulty in the
> setup.

Should not be dificult.  As long as you have the proper kernel drivers
loaded.  Just tell gpsd to use /dev/ttyACM0 instead of /dev/ttyAMA0

> I'm not obtaining anything when I attempt the command cat
> /dev/serial0.

Nor should you, that is the GPIO serial, not the USB serial.

> I've paused here because according to all the
> instructions I should be getting a readout of NMEA sentences and this
> confirms that the GPS is giving out data. The GPS isn't the problem,
> I can obtain data from it in a different software so I'm having
> issues trying to set it up correctly.

Yup.

> What I have done so far to connect the GPS:
> 
>    - Enabled serial hardware in the rapsi-config

Which activates the serial port, not the USB port.
>    - attempted to set up connection to my devices to the ports
> ttyACM0, ttyAMA0, ttyS0, serial0----(ttyACM0 is the USB connection
> between my flight controller and RPi).

Well, that is going to confuse things, two devices on USB ports.
Look at 'dmesg' it should tell you which port the M8030 got assigned to.

> Each of these have been
> connected to both the DEVICES and GPSD_OPTIONS.

Oh.  You negelected to mention you are using systemd(umb).

I don't use systemd(umber).  Someone else will have to help with that
if you want to continue with sysmed(umbest).

>    - Inspected the /boot/config.txt and checked enable_uart=1,
>    dtoverlay=pi3-disable-bt

Once again, that is for the GPIO serial, so not relevant.

>    - Inspected /boot/cmdline.txt does not have console=serial0, 115200

Once again, that is for the GPIO serial, so not relevant.

>    - It's speed is set at 9600 and tested at 115200 as well

ttyACM USB serial has no speed.  Merely a placebo.

>    - I've set the devices to ACM0 for a while, it had some connection
> but no readings and the drone was sending out warnings

You said your drone was on ACM0, so not a surprise.

>    - Used the command ls -l /dev to identify that serial0 --->ttyAMA0
> and serial1--->ttyS0

Once again, that is for the GPIO serial, so not relevant.

>    - Below is the dmesg | grep tty:

Not enough detail for me to see what happened.

> May I ask for advice or suggestions to fix my current RPi and GPS
> connection situation?

a) Disable systemd(rool) with gpsd.
b) Run gpsdebuginfo as root, and send us that output.  Your gpsd is too old,
so get a copy here: https://gpsd.io/gpsdebuginfo


RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        gem@rellim.com  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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