I’m testing a Cellular IoT Application Shield, which supports LTE, GNSS, and environmental sensors. I’m currently trying to establish a ppp connection, read gps data (gpsd), and read sensor data all at the same time. It seems that the USB interfaces required for this are not showing up, no matter what I try.
Expected devices:
ttyUSB0→DM
ttyUSB1→For GPS NMEA message output
ttyUSB2→For AT command communication
ttyUSB3→For PPP connections or AT command communication
As per documentation, GNSS data is only available through USB. When the IoT shield is installed on the 40-pin header, the raspberry pi is able to communicate with the shield on /dev/ttyS0 with supplied sample scripts. If I connect a USB cable between the shield and raspberry pi in this configuration, no new USB devices seem to be added. lsusb shows no additional devices, either.
If I only connect the USB cable without installing the shield on the 40-pin header, I can’t seem to communicate with the shield at all.
How should I go about getting the expected interfaces? Am I missing any drivers on Linux, if so, is this shield/chip not supported on the mainline kernel?
My kernel is 4.19.97-v7 on the raspberry pi 3b. My loaded modules: i2c-dev, qmi_wwan, qcserial, option
Thanks for your help