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M.2 Key B Connector

The M.2 Key B connector on the COM Carrier Board V2 has three interfaces: USB, SATA and SIM card. The SATA interface testing is explained in the SATA section.

This test uses a Sierra Wireless AirPrime EM7305 module (https://source.sierrawireless.com/devices/em-series/em7305/) and a SIM card. It should be possible to use any USB modem with the correct M.2 key and form factor but other modems may require specific Linux drivers, use different USB serial ports and maybe different commands.

U-Boot​

Currently not supported.

Linux​

Start by checking that the module is detected. There should be a Sierra Wireless device like this.

lsusb
Bus 001 Device 004: ID 1199:68c0 Sierra Wireless, Inc.
Bus 001 Device 003: ID 0424:2740 Standard Microsystems Corp.
Bus 001 Device 002: ID 0424:2744 Standard Microsystems Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Verify that the serial devices have been created.

ls -l /dev/serial/by-id/
lrwxrwxrwx 1 root root 13 Feb 8 10:05 usbSierra_Wireless__Incorporated_EM7305-if00-port0 -> ../../ttyUSB0
lrwxrwxrwx 1 root root 13 Feb 8 10:05 usbSierra_Wireless__Incorporated_EM7305-if02-port0 -> ../../ttyUSB1
lrwxrwxrwx 1 root root 13 Feb 8 10:05 usbSierra_Wireless__Incorporated_EM7305-if03-port0 -> ../../ttyUSB2

If there are no Sierra usb devices then check that the kernel has been configured with support for the device. In this case the configuration option is CONFIG_USB_SERIAL_QUALCOMM.

cp /proc/config.gz .
gunzip config.gz
grep CONFIG_USB_SERIAL_QUALCOMM config
CONFIG_USB_SERIAL_QUALCOMM=m

Start miniterm with the exit code parameter 27 to use the ESC key to terminate the program instead of the default Ctrl+].

miniterm.py --exit-char 27 /dev/ttyUSB2 115200
--- Miniterm on /dev/ttyUSB2 115200,8,N,1 ---
--- Quit: Ctrl+[ | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H
---

Type AT and then press Enter to see if the Sierra module responds at all. If there is no OK response then exit (ESC key) and try one of the other usb port.

AT
OK

If AT worked the type AT+CPINR and press Enter. If the SIM card is inserted and the interface is working then it should report a number of stats.

AT+CPINR
+CPINR: SIM PIN,3
+CPINR: SIM PUK,10
+CPINR: SIM PIN2,3
+CPINR: SIM PUK2,10
+CPINR: PH-FSIM PIN,255
...
+CPINR: PH-SP PUK,1
+CPINR: PH-CORP PUK,1
OK

If the SIM card is not inserted or the interface is not working then the command will return this response.

AT+CPINR
+CME ERROR: SIM not inserted

Exit the miniterm program with the ESC key.