My Thinkpad Tablet 10 contains a Sierra Wireless EM7345 3G/LTE modem, which works fine as LTE modem (using MBIM interface). Many 3G modems also contain, for what reason ever, a GNSS (Global Navigation System) receiver, commonly called GPS which is confusing since nowadays we do not only have GPS satellites hanging in the sky but also GLONASS, WAAS, EGNOS, Galileo and Beidou. But anyway, let’s call it GPS for now.
The EM7345 in the TPT10 is almost the same as the module used in current Thinkpad notebook computers like the X1 and some more, so one can find quite a bunch of information about it. The EM7345 in the TPT10 is by default configured to use MBIM only, but the GPS function is not available over MBIM. But the EM7345 can also expose additional pseudo serial ports for AT commands using the USB ACM (Asynchronous Communication Model). This mode can be enabled by a Windows program, a good web page discussing this is here. You need to run EM7345_MBIM_ACM.exe once in Windows and after that three new ACM ports will become available – and stay being available across reset and power cycle. There is a seconds Windows application to disable the ACM mode again but I have not been able to find the file yet.
The function of the three ACM ports is reported differently over the net, it seems that there are different versions of the EM7345 floating around, or different firmware versions. The three ACM port on my TPT10 can be described as:
- ACM0 – Can be used with AT commands, responds with extended error codes like „+CME ERROR: <n>“
- ACM1 – Does not respond to AT commands, some reports say that one of the three port is a trace port, maybe this one?
- AMC2 – Does respond to AT commands, responds with simple error codes like plain „ERROR“
Once you have the ports available you can issues AT commands like
AT+XGENDATA +XGENDATA: " FIH7160_XMM7160_V1.1_MBIM_GNSS_NAND_REV_4.5 2013-Dec-20 12:14:04 *FIH7160_V1.1_MODEM_01.1349.12*" "*"
You can get a full list of supported AT commands by issuing AT+CLAC. The modem supports the AT attributes „?“ and „=?“ for most of its AT commands which reveals possible command options, their parameters (using ?) and their current state.
Still open issues / question: Up until now I was not able to get a NMEA GPS data stream out of the modem yet, but GPS coordinate reports in some other format. There are AT commands though that suggest that the modem can also support NMEA.