So, it looks like the expansion card has GPS. Does anyone know how to access it?
Do you need to have a SIM card for it to work? I’d read that GPS was separate from cell service and didn’t need an internet connection on phones—so I’m guessing that it might be accessible without a SIM card.
I saw on one of the pages it says it needs a GPS antenna—but I haven’t found any specifications on what kind of antenna it needs.
Yes, you can access the GPS.
For antenna, you could use a standard GNSS antenna(L1 freq) with builtin LNA. According to the schematics, the antenna socket is powered, so LNA will work. I’ve tested one on my device.
For software, you need to use Modem Manager(MM) to enable the GNSS function. Due to an implementation issue of MM, the GNSS function cannot work without an actual sim card inserted.
Then you have two options: either use gpsd or use MM+dbus. gpsd need full control over GNSS serial port(ttyUSB1 if I’m right), so the command line option for enabling the GNSS function is different.
mmcli -m any --location-enable-gps-unmanaged
mmcli -m any --location-enable-gps-nmea --location-enable-gps-raw
As to the configurations for gpsd, please refer to it’s manual.
This page seems to imply that it should be possible: Techship - FAQ - Basic GNSS/GPS usage guide for SIMcom SIM7100, SIM7500, SIM7600 series cellular modules
I was able to do the following (without a SIM card):
- Install minicom:
sudo apt install minicom
- Turn on the expansion card:
- Connect minicom to the modem:
minicom -D /dev/ttyUSB3
Then I could send AT commands to the modem. For example, I sent the following:
AT → OK
AT+CVAUXS=0 → OK
AT+CGPS=1,1 → OK
AT+CGPSINFO → ,
So, something’s not quite working. The last command should have been the current GPS location.
cat /dev/ttyUSB1 does return data. I have no idea how to use it yet…but it seems like a step in the right direction. Turning GPS off in minicom stopped the data, as expected.