Serial Devices/Modem not recognised in /dev

lsusb shows the device connected and plugged in but cannot see any of the /ttyUSBx or /modem. Cannot find any solution to this problem and any help would be greatly appreciated.

Hi,

Can you share the following outputs of the following Linux commands:

  • cat /etc/os-release
  • uname -a
  • lsusb
  • lsusb -t
  • usb-devices
  • dmesg | grep tty
  • ls -l /sys/bus/usb-serial/devices
PRETTY_NAME="Debian GNU/Linux 11 (bullseye)"
NAME="Debian GNU/Linux"
VERSION_ID="11"
VERSION="11 (bullseye)"
VERSION_CODENAME=bullseye
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"
  • uname -a
Linux Intruck1 5.15.32-v8+ #1538 SMP PREEMPT Thu Mar 31 19:40:39 BST 2022 aarch64 GNU/Linux
  • lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 1bc7:1205 Telit Wireless Solutions LE910C4-AP
Bus 001 Device 002: ID 2109:3431 VIA Labs, Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
  • lsusb -t
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 5000M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/1p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/4p, 480M
        |__ Port 1: Dev 3, If 0, Class=Communications, Driver=cdc_mbim, 480M
        |__ Port 1: Dev 3, If 1, Class=CDC Data, Driver=cdc_mbim, 480M
  • usb-devices
T:  Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=480 MxCh= 1
D:  Ver= 2.00 Cls=09(hub  ) Sub=00 Prot=01 MxPS=64 #Cfgs=  1
P:  Vendor=1d6b ProdID=0002 Rev=05.15
S:  Manufacturer=Linux 5.15.32-v8+ xhci-hcd
S:  Product=xHCI Host Controller
S:  SerialNumber=0000:01:00.0
C:  #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=0mA
I:  If#=0x0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub

T:  Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  2 Spd=480 MxCh= 4
D:  Ver= 2.10 Cls=09(hub  ) Sub=00 Prot=01 MxPS=64 #Cfgs=  1
P:  Vendor=2109 ProdID=3431 Rev=04.21
S:  Product=USB2.0 Hub
C:  #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=100mA
I:  If#=0x0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub

T:  Bus=01 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#=  3 Spd=480 MxCh= 0
D:  Ver= 2.00 Cls=ef(misc ) Sub=02 Prot=01 MxPS=64 #Cfgs=  1
P:  Vendor=1bc7 ProdID=1205 Rev=03.18
S:  Manufacturer=Android
S:  Product=LE910C4-AP
S:  SerialNumber=091010403
C:  #Ifs= 2 Cfg#= 1 Atr=a0 MxPwr=500mA
I:  If#=0x0 Alt= 0 #EPs= 1 Cls=02(commc) Sub=0e Prot=00 Driver=cdc_mbim
I:  If#=0x1 Alt= 1 #EPs= 2 Cls=0a(data ) Sub=00 Prot=02 Driver=cdc_mbim

T:  Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=5000 MxCh= 4
D:  Ver= 3.00 Cls=09(hub  ) Sub=00 Prot=03 MxPS= 9 #Cfgs=  1
P:  Vendor=1d6b ProdID=0003 Rev=05.15
S:  Manufacturer=Linux 5.15.32-v8+ xhci-hcd
S:  Product=xHCI Host Controller
S:  SerialNumber=0000:01:00.0
C:  #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=0mA
I:  If#=0x0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub

-dmesg | grep tty

[    0.000000] Kernel command line: coherent_pool=1M 8250.nr_uarts=0 snd_bcm2835.enable_compat_alsa=0 snd_bcm2835.enable_hdmi=1  smsc95xx.macaddr=E4:5F:01:BA:64:A7 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000  console=ttyS0,115200 console=tty1 root=PARTUUID=624e2549-02 rootfstype=ext4 fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles
[    0.000302] printk: console [tty1] enabled
[    1.467789] fe201000.serial: ttyAMA0 at MMIO 0xfe201000 (irq = 19, base_baud = 0) is a PL011 rev2
[    3.166783] systemd[1]: Created slice system-getty.slice.
  • ls -l /sys/bus/usb-serial/devices
ls: cannot access '/sys/bus/usb-serial/devices': No such file or directory

Send MBIM_OPEN message to the modem with the following command and wait 3 sec.

echo 01 00 00 00 10 00 00 00 01 00 00 00 00 10 00 00 | xxd -r -p >/dev/cdc-wdm0

Send USB composition with the following command:

echo 03 00 00 00 32 00 00 00 05 00 00 00 01 00 00 00 00 00 00 00 54 65 6c 69 74 4d 42 49 4d 45 78 74 65 6e 64 53 01 00 00 00 01 00 00 00 02 00 00 00 00 00 | xxd -r -p >/dev/cdc-wdm0

Note: You might need root permission to do this: sudo su

Solved! thank you very much