GPS via USB?

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  • #9434
    GregOMC
    Participant

    Hi OzzMaker,

    Nice module. I've been able to get a ppp connection working with the BerryGPS-GSM via USB on RPi 3b+. However I can't see the GPS forwarding via /dev/ttyACM3 (using cat or screen). The green GPS LED is flashing, so it should have a fix.

    By preference I haven't added the female header to connect the module to the GPIO.

    Are there any extra steps I need to do for the GPS data to be forwarded on ttyACM3? Should I expect GPS NMEA to be streaming on that device?

    Thanks,

    GregOMC

    #9435
    PeterP
    Participant

    Hi Greg

    By default, the NMEA sentences are streamed as usual from the GPS module to the Pi TX/RX pins.

    you can stream the gps NMEA sentences through  one of USB serial interfaces .We have a guide in draft.. ill get it published in the next few days.

    In summary, this is what you need to do.
    Connect to the second interfaces on the GSM module;
    minicom -b 115200 -o -D /dev/ttyACM1
    Activate storing of last values of NMEA, from the GPS to the GSM module;

    AT+UGRMC=1
    AT+UGGLL=1
    AT+UGGSV=1
    AT+UGGGA=1

    Activate the unsolicited aiding result.
    AT+UGIND=1
    Set NMEA data to stream through USB interface /dev/ttyACM3
    AT+UGPRF=1
    Turn on GPS,  (Start GNSS with GPS+SBAS+GLONASS systems and local aiding.);
    AT+UGPS=1,2,67

    To view the stream
    minicom -b 115200 -o -D /dev/ttyACM3

    To stop GPS, use
    AT+UGPS=0

    We have some info here about the UGPS command which is used to turn on GPS.

    This document describes these all these commands in detail.

    If you need to free up the RX/TX pins on the Pi (because the GPS will still be using them)
    We did include a serial switch to get over this issue. On the back, there are two jumpers to control this switch.
    Soldering the jumper JP1 closed (just place a solder blob on top) will connect to GSM module to the Pi serial interface.
    Soldering a the jumpers JP1 and JP3 closed, will free up the Pi Serial port to be used by another device . Then then can use the four pins near the uFL connector for the GSM to access the pi TX/RX pins.

    I hope this helps

    rgds
    Peter

    Peter --OzzMaker.com --

    #9436
    GregOMC
    Participant

    Thanks for the quick reply Peter! I'll give your instructions a go, and look forward to seeing the guide when it's ready.

    Regarding your explanation for RX/TX pins, I'm guessing that this only applies when the module is connected to the Pi GPIO pins? Ideally I'd like to leave the GPIO pins free for other modules.

     

     

     

    #9438
    PeterP
    Participant

    yes.. you are right.  if connected via USB only, you don't need to worry about the TX/RX pins on the Pi

    Peter --OzzMaker.com --

    #9455
    GregOMC
    Participant

    Thanks Peter, those commands did the trick nicely.

    Referring to the Assisted GPS fix page also helps, so thanks for that as well.

     

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