Modem

Overview⚓︎

The modems in Host Mobility's products typically provide support for both mobile (cellular) networks and Global Positioning System (GPS) functionality. Although communication methods with the modems may vary across our product range, this page highlights the shared common features among all the integrated modems in our products.

Platform specific⚓︎

HMX

Communication channels⚓︎

Quectel
- Radio /dev/ttyUSB0
- GPS /dev/ttyUSB1
- AT commands /dev/ttyUSB2
- 4G/LTE /dev/ttyUSB3
Gemalto
- Radio /dev/ttyACM0
- GPS /dev/ttyACM1
- AT commands /dev/ttyACM2
- 4G/LTE /dev/ttyACM3

Controlling the modem with AT commands⚓︎

Simple read and write⚓︎

cat /dev/ttyACM2
echo "AT+CFUN?" > /dev/ttyACM2

Better way to read and write⚓︎

Use microcom to connect to the modem. (Exit microcom with CTRL-X)

microcom /dev/ttyUSB2
# or, for PLS8 modems
microcom /dev/ttyACM2

To get more informative error messages, you can type:⚓︎

AT+CMEE=2

Expected reply

OK

Mobile network⚓︎

Test mobile network⚓︎

List all current network operators:
```
AT+COPS=?`
```
After 20--30 seconds, you get something similar to:

+COPS: (1,"3 SE","3 SE","24002",7),(1,"Telenor SE","TelenorS","24008",7),(1,"Tele2","Tele2 SE","24007",7),(1,"TELIA S","TELIA","24001",7),(1,"TELIA S","TELIA)

Check status of PIN code protection⚓︎

type

AT+CPIN?

expected:

+CPIN: READY

error:

+CME ERROR: SIM not inserted

Global Positioning System (GPS)⚓︎

Time⚓︎

The GPS time can be extracted from the $GPRMC string outputted by the GPS.

This time is backed up to facilitate faster GPS fix times, avoiding the need to restart from scratch with each GPS engine restart.

Additionally, this backed-up time serves as a fallback for applications in case the system time cannot be synchronized from the Internet for any reason. Please note that our default BSPs currently do not utilize this feature.