Serial communication using Raspberry Pi 4G/LTE Cellular Modem Kit

victor.sanchez · November 25, 2020, 12:54am

I am configuring the Raspberry Pi 4G/LTE Cellular Modem Kit with the Telit 910c01-EU into a Raspberry Pi 4. For this purpose, I am using the following tutorial:

“Internet Connection with Telit LE910C1 module using ECM Mode” (https://docs.sixfab.com/page/internet-connection-with-telit-le910c1-module-using-ecm-mode)

When opening the serial communication, I have no /dev/ttyUSBx as illustrated in the tutorial; therefore, I think I have no option to configure the modem (at least using the AT commands). On the other hand, the new network interface (created when I plug the HAT into the RPi) is called usb0 instead of wwan0, as expected. I have examined other tutorials for different operation modes, and perhaps the modem is configured in another mode.

Is there any possibility to factory reset the devices? In case not, is there any possibility to configure the modem for the Internet connection?

I will appreciate a lot any help you can provide or any advice since I am blocked.

Many thanks for considering my request, and thank you so much for your attention.

ensar · November 25, 2020, 7:54pm

Hi @victor.sanchez,

Could you please provide the output of the following command?

uname -sr
lsusb -t
sudo cat /sys/kernel/debug/usb/devices
dmesg | grep tty

victor.sanchez · November 25, 2020, 11:23pm

Hello @ensar,

Thanks for your quick response. Please find down below the output of the commands:

uname -sr
Linux 5.4.51-v7l+

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 5, Class=Vendor Specific Class, Driver=, 480M
        |__ Port 1: Dev 3, If 3, Class=Vendor Specific Class, Driver=, 480M
        |__ Port 1: Dev 3, If 1, Class=CDC Data, Driver=rndis_host, 480M
        |__ Port 1: Dev 3, If 6, Class=Vendor Specific Class, Driver=, 480M
        |__ Port 1: Dev 3, If 4, Class=Vendor Specific Class, Driver=, 480M
        |__ Port 1: Dev 3, If 2, Class=Vendor Specific Class, Driver=, 480M
        |__ Port 1: Dev 3, If 0, Class=Communications, Driver=rndis_host, 480M
        |__ Port 1: Dev 3, If 7, Class=Vendor Specific Class, Driver=, 480M
        |__ Port 2: Dev 5, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 3: Dev 4, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 3: Dev 4, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M

sudo cat /sys/kernel/debug/usb/devices

T:  Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=480  MxCh= 1
B:  Alloc=  0/800 us ( 0%), #Int=  0, #Iso=  0
D:  Ver= 2.00 Cls=09(hub  ) Sub=00 Prot=01 MxPS=64 #Cfgs=  1
P:  Vendor=1d6b ProdID=0002 Rev= 5.04
S:  Manufacturer=Linux 5.4.51-v7l+ xhci-hcd
S:  Product=xHCI Host Controller
S:  SerialNumber=0000:01:00.0
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=  0mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
E:  Ad=81(I) Atr=03(Int.) MxPS=   4 Ivl=256ms

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= 4.21
S:  Product=USB2.0 Hub
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=100mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
E:  Ad=81(I) Atr=03(Int.) MxPS=   1 Ivl=256ms

T:  Bus=01 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#=  3 Spd=480  MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=1bc7 ProdID=1203 Rev= 3.18
S:  Manufacturer=Android
S:  Product=LE910C1-EU
S:  SerialNumber=0123456789ABCDEF
C:* #Ifs= 8 Cfg#= 1 Atr=a0 MxPwr=500mA
A:  FirstIf#= 0 IfCount= 2 Cls=02(comm.) Sub=06 Prot=00
I:* If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=02 Prot=ff Driver=rndis_host
E:  Ad=82(I) Atr=03(Int.) MxPS=   8 Ivl=32ms
I:* If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=rndis_host
E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 2 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E:  Ad=83(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 3 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=42 Prot=01 Driver=(none)
E:  Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 4 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
E:  Ad=86(I) Atr=03(Int.) MxPS=  10 Ivl=32ms
E:  Ad=85(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 5 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
E:  Ad=88(I) Atr=03(Int.) MxPS=  10 Ivl=32ms
E:  Ad=87(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 6 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
E:  Ad=8a(I) Atr=03(Int.) MxPS=  10 Ivl=32ms
E:  Ad=89(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=06(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 7 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
E:  Ad=8c(I) Atr=03(Int.) MxPS=  10 Ivl=32ms
E:  Ad=8b(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=07(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms

T:  Bus=01 Lev=02 Prnt=02 Port=01 Cnt=02 Dev#=  5 Spd=1.5  MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs=  1
P:  Vendor=046d ProdID=c03e Rev=20.00
S:  Manufacturer=Logitech
S:  Product=USB-PS/2 Optical Mouse
C:* #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr= 98mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=03(HID  ) Sub=01 Prot=02 Driver=usbhid
E:  Ad=81(I) Atr=03(Int.) MxPS=   4 Ivl=10ms

T:  Bus=01 Lev=02 Prnt=02 Port=02 Cnt=03 Dev#=  4 Spd=1.5  MxCh= 0
D:  Ver= 1.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs=  1
P:  Vendor=1c4f ProdID=0026 Rev= 1.10
S:  Manufacturer=SIGMACHIP
S:  Product=USB Keyboard
C:* #Ifs= 2 Cfg#= 1 Atr=a0 MxPwr= 98mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=03(HID  ) Sub=01 Prot=01 Driver=usbhid
E:  Ad=81(I) Atr=03(Int.) MxPS=   8 Ivl=10ms
I:* If#= 1 Alt= 0 #EPs= 1 Cls=03(HID  ) Sub=00 Prot=00 Driver=usbhid
E:  Ad=82(I) Atr=03(Int.) MxPS=   3 Ivl=10ms

T:  Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=5000 MxCh= 4
B:  Alloc=  0/800 us ( 0%), #Int=  0, #Iso=  0
D:  Ver= 3.00 Cls=09(hub  ) Sub=00 Prot=03 MxPS= 9 #Cfgs=  1
P:  Vendor=1d6b ProdID=0003 Rev= 5.04
S:  Manufacturer=Linux 5.4.51-v7l+ xhci-hcd
S:  Product=xHCI Host Controller
S:  SerialNumber=0000:01:00.0
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=  0mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
E:  Ad=81(I) Atr=03(Int.) MxPS=   4 Ivl=256ms

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 snd_bcm2835.enable_headphones=1 video=HDMI-A-1:1920x1080M@60,margin_left=48,margin_right=48,margin_top=48,margin_bottom=48 smsc95xx.macaddr=DC:A6:32:44:89:38 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000  console=ttyS0,115200 console=tty1 root=/dev/mmcblk0p7 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles
[    0.001088] printk: console [tty1] enabled
[    1.168388] fe201000.serial: ttyAMA0 at MMIO 0xfe201000 (irq = 29, base_baud = 0) is a PL011 rev2
[    2.971258] systemd[1]: Created slice system-getty.slice.

If you need any other command output please let me know.

Thanks :)!

ensar · November 26, 2020, 12:16pm

Telit RNDIS compositision is supported by linux 5.4.77+

Upgrading the kernel to 5.4.77 should support the drivers.

sudo rpi-update cc9ff6c7d1b9be5465c24c75941b049f94a6bd32

Reboot the RPi after the upgrade. Then it should work fine. You can have access to the ttyUSB(s)

Thank you.

victor.sanchez · November 26, 2020, 1:43pm

Thank you very much for your response. I have updated the kernel to 5.4.77, and now I can access the ttyUSB(s). Your comment solved my problem, allowing me to follow the tutorial and configure everything correctly.