MC7455 - /dev/ttyUSB2 is not working

IoT Modules MC/EM Series
1

Hello,

I am using MC7455 for my project. I have connected the module through USB to PCIe adapter. On startup I could see that the device is attached to my system.

root@cl-som-imx7:~# lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 003: ID 1199:9071 Sierra Wireless, Inc.

root@cl-som-imx7:~# ls -l /dev/ttyUSB*
crw-rw---- 1 root dialout 188, 0 Sep 7 12:17 /dev/ttyUSB0
crw-rw---- 1 root dialout 188, 1 Sep 7 12:17 /dev/ttyUSB1
crw-rw---- 1 root dialout 188, 2 Sep 7 12:17 /dev/ttyUSB2

and also I have two /cdc/wdm interfaces.

I want to activate the GPS functionalities. So to send the AT commands, I tried opening the interface ttyUSB2 using minicom. The baudrate is 115200.I am seeing the following messages on the terminal:

tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_write - 1 byte(s)
tty ttyUSB2: serial_tiocmget
tty ttyUSB2: serial_ioctl - cmd 0x5401
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_tiocmget
tty ttyUSB2: serial_ioctl - cmd 0x5401
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_tiocmget
tty ttyUSB2: serial_ioctl - cmd 0x5401
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_tiocmget
tty ttyUSB2: serial_ioctl - cmd 0x5401
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_tiocmget
tty ttyUSB2: serial_ioctl - cmd 0x5401
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_tiocmget
tty ttyUSB2: serial_ioctl - cmd 0x5401
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_tiocmget
tty ttyUSB2: serial_ioctl - cmd 0x5401
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room

I tried using other USB interfaces, I am seeing similar messages. Any information on how to fix this will help me.

Linux Kernel Version : 4.9.39

Thanks & Regards,
Vinothkumar

2

Vino,

Are literally seeing text such as ‘serial_write_room’ come out of minicom from /dev/ttyUSB2? BTW the baud rate does not matter with USB as it automatically adjusts.

Regards

Matt

3

Oh yeah also make sure modem manager is off as well. That is the only time I have seen AT commands being sent to the unit while I have been in minicom.

Regards

Matt