The modem also has an USB port that can be routed to the smartphone/tablet USB port.
To do that you first need to get a root shell in the device as the commands need to be executed as root.
Once this is done you need to switch the USB connector to the modem USB. This can be done with the following command:
echo MODEM > /sys/devices/virtual/sec/switch/usb_sel
Then nothing will happen, you will still be able to login through adb.
To make the device switch to the modem USB you then need to unplug and replug the USB cable between your computer and the device.
At this point, if the modem was booted, you'll see a new USB device appearing.
Some serial ports will also appear.
Tested on Replicant 6.0 0004 RC3
| Device | Distribution | Modem status | USB ids (lsusb from laptop) | tty |
| GT-I9100 | Replicant 6.0 0004 RC3 | Off | None | N/A |
| GT-I9100 | Replicant 6.0 0004 RC3 | Booted | 1519:0020 Comneon HSIC Device | /dev/ttyACM0 -> /dev/ttyACM6 |
| GT-I9300 | Replicant 6.0 0004 RC3 | Booted | 1519:0020 Comneon HSIC Device | /dev/ttyACM0 -> /dev/ttyACM6 |
When running lsusb on the SOC on the Replicant 11 kernel on a GT-I9300, we also see 1519:0020 Comneon HSIC Device once the modem is booted. Once powered on and before booting, the USB ids seen in lsusb with that kernel are these ones: 058b:0041 Infineon Technologies Flash Loader utility instead.
As the modem isn't visible either when not powered on, we need to look if it's possible to boot the modem from a laptop for instance.
| Device | State | UART | Protocol |
|---|---|---|---|
| GT-I9100 | modem booted | /dev/ttyACM0 | AT: GTI9100ModemTTYACM0 |
| GT-I9100 | modem booted | /dev/ttyACM1 | Compatible with xgoldmon |
| GT-I9300 | modem booted | /dev/ttyACM0 | AT: GTI9300ModemTTYACM0 |
| GT-I9100 | modem booted | /dev/ttyACM1 | Xgoldmon waits for messages but nothing arrives |
description: Xgoldmon is a software that can get some cellular protocol traces from some Samsung phones using the samsung-ipc protocol.
git: https://github.com/2b-as/xgoldmon.git
Xgoldmon seem to display things on the GT-I9100:
# ./xgoldmon -vvvv -i localhost -t s2 -l /dev/ttyACM1 LOG:>>[HIGH]oembatt.c,310,[DISP] Thermistor : measured_value=1630666778<< LOG:>>[HIGH]oembatt.c,137,[DISP] oem_set_batt_level : 4220<< LOG:>>[HIGH]oembatt.c,236,[DISP] BATT : measured_value_mv=4220, AvgBattVal_mv=4007, battery_level=5<< LOG:>>[LOW]oemdisplay.c,363,no change -> rssi:4, bat:5<< LOG:>>[HIGH]oembatt.c,310,[DISP] Thermistor : measured_value=1630666779<< LOG:>>[HIGH]oembatt.c,137,[DISP] oem_set_batt_level : 4225<< LOG:>>[HIGH]oembatt.c,236,[DISP] BATT : measured_value_mv=4225, AvgBattVal_mv=4026, battery_level=5<< LOG:>>[LOW]oemdisplay.c,363,no change -> rssi:4, bat:5<< LOG:>>[HIGH]oembatt.c,310,[DISP] Thermistor : measured_value=1630666778<< LOG:>>[HIGH]oembatt.c,137,[DISP] oem_set_batt_level : 4220<< LOG:>>[HIGH]oembatt.c,236,[DISP] BATT : measured_value_mv=4220, AvgBattVal_mv=4055, battery_level=5<< LOG:>>[LOW]oemdisplay.c,363,no change -> rssi:4, bat:5<<
And when calling an (inexisting/invalid) number, the frames appear in Wireshark.
However on the GT-I9300 it waits for messages that never arrive.
And on the GT-I9100 there seem to be very few messages.
So maybe AT+TRACE=1 enables tracing but doesn't set the tracing verbosity.