EM7455B missing /dev/ttyUSB

[b9jo1zlripn]

Hello everyone!

I’m having trouble with the serial device for my EM7455B. The device isn’t showing up.

~# lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux 5.15.150 xhci-hcd xHCI Host Controller
Bus 001 Device 003: ID 413c:81b6 Sierra Wireless, Incorporated DW5811e Snapdragon™ X7 LTE
Bus 001 Device 002: ID 1a40:0101  USB 2.0 Hub
Bus 001 Device 001: ID 1d6b:0002 Linux 5.15.150 xhci-hcd xHCI Host Controller
~# ls -alh /dev/tty*
crw-rw-rw-    1 root     root        5,   0 Apr  3 16:23 /dev/tty
crw-rw----    1 root     dialout     4,  64 Jan  1  1970 /dev/ttyS0
crw-rw----    1 root     dialout     4,  65 Jan  1  1970 /dev/ttyS1
crw-rw----    1 root     dialout     4,  74 Jan  1  1970 /dev/ttyS10
crw-rw----    1 root     dialout     4,  75 Jan  1  1970 /dev/ttyS11
crw-rw----    1 root     dialout     4,  76 Jan  1  1970 /dev/ttyS12
crw-rw----    1 root     dialout     4,  77 Jan  1  1970 /dev/ttyS13
crw-rw----    1 root     dialout     4,  78 Jan  1  1970 /dev/ttyS14
crw-rw----    1 root     dialout     4,  79 Jan  1  1970 /dev/ttyS15
crw-rw----    1 root     dialout     4,  66 Jan  1  1970 /dev/ttyS2
crw-rw----    1 root     dialout     4,  67 Jan  1  1970 /dev/ttyS3
crw-rw----    1 root     dialout     4,  68 Jan  1  1970 /dev/ttyS4
crw-rw----    1 root     dialout     4,  69 Jan  1  1970 /dev/ttyS5
crw-rw----    1 root     dialout     4,  70 Jan  1  1970 /dev/ttyS6
crw-rw----    1 root     dialout     4,  71 Jan  1  1970 /dev/ttyS7
crw-rw----    1 root     dialout     4,  72 Jan  1  1970 /dev/ttyS8
crw-rw----    1 root     dialout     4,  73 Jan  1  1970 /dev/ttyS9

I’m running OpenWrt (23.05.3, r23809-234f1a2efa) on a Banana Pi BPI-R3.

I found in this forum these threads:
https://forum.sierrawireless.com/t/my-mc7710-cant-work-on-linux-after-plug-in-it-to-windows8/7986
https://forum.sierrawireless.com/t/em7455-error-with-usbcomp-over-cdc-wdm0/15571
Following the posts there I did send the posted hex commands to the modem. It seemed to work, or at least I did get the expected response from the modem, no error message. But still, after reboot, no serial device.

Unfortunately I can’t test the suggested perl script: https://www.thinkpenguin.com/files/em7455-modem-software/swi_setusbcomp.pl
OpenWrt does not contain the required perl packages.

I would be very thankful if someone could give me hint on how to enable the serial device for my modem.

[jyijyi]

see if this helps:

EM7455 Linux Issues

I found the IDs by googling for DW5811e, guessing that the bood PID is one less than the application PID. Usually is. Most USB serial functions are very simple: One bulk in and one bulk out endpoint is all you need. There is some control signal logic as well, but that’s mostly optional. This makes the drivers simple and in practice interchangeable. The main difference is in the descriptor matching. I often abuse the “option” driver for this kind of one-shot temporary thing because it does …

[b9jo1zlripn]

Thank you for responding!

Unfortunately the thread you posted doesn’t help me. I didn’t change any PID. The modem is showing up on lsusb. There’s also a /dev/cdc_wdm0. The kernel modules usbserial, qcserial, usb_wwan are loaded. But there is no /dev/ttyUSB present at all.

[jyijyi]

how about echo new id to the driver?

EM7455 Linux Issues

Sure, no problems. But please take it calm and easy and don’t do anything more hasty Your modem had a Dell specific ID. This is made up of both a vendor ID (which belongs to Dell) and a product ID, which was assigned by Dell. The WIndows drivers know this exact combination. You changed half of that device ID, by changing the product ID. So you now have a bastard modem with a Dell vendor ID and Sierra Wireless product IDs. This combination is not recognized by neither Windows nor L…

[b9jo1zlripn]

Yes. I did try that. It doesn’t have any effect.

But that command would just temporary fix a wrong PID (or vendor ID), correct?
And I did not change any PID.

[jyijyi]

at least can see if the AT command is enumerated

[b9jo1zlripn]

I’m not sure what you mean.
Sorry I don’t know a lot about modems and how to operate them.

If you’re talking about sending AT commands to the modem then I need a working serial console first. Without /dev/ttyUSB that’s going to be difficult.
Correct me please if I’m wrong.

[jyijyi]

are you able to test in Windows?

DW5811e / EM7455 Problem with Windows 11 - failure "insert sim"

Hello, i installed a used "DM5811e card into my DELL notebook and did a firmware upgrade to the latest version of the card and install the original Dell drivers: DW5811e-Qualcomm-Snapdragon-X7-LTE-and-GPS-driver_CC17M_WIN_7.42.4705.501_A02 than I updated the drivers with the Sierra Generic drivers: GenericDriverSetup_8.14.5087.0005 It looks good so far, but Windows 11 tells me to “Insert SIM card”… but my SIM card is inside. I used another DW5811e card already in the same computer with Wi…

[b9jo1zlripn]

No, unfortunately I can’t.
I currently don’t have a m.2 to USB adapter that need to plug it into a Windows machine.
Sorry.

[jyijyi]

can you install windows virtual machine in your linux PC?

Here says you can use windows driver to enable the AT port:

USSD Software for Windows 10

that was the qualcomm modem i placed in my laptop [image]

[b9jo1zlripn]

I can’t do that either.
It’s banana pi router with 2Gb RAM and 8Gb Flash containing the root-fs.

I’m currently trying to rebuild libqmi for OpenWrt since the version that it comes with is missing SWI features that I hope I can use to change the usb composition. Maybe that gives me the serial device I need.

[jyijyi]

ok, good luck for you!