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.
Set NMEA data to stream through USB interface /dev/ttyACM3
Turn on GPS, (Start GNSS with GPS+SBAS+GLONASS systems and local aiding.);
To view the stream
minicom -b 115200 -o -D /dev/ttyACM3
To stop GPS, use
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
Peter --OzzMaker.com --