EM7455 with OpenWrt

IoT Modules MC/EM Series
1

I am having some issues trying to configure this modem Sierra Airwireless EM7455 with T-Mobile, in Openwrt.
I did make it work with windows, but I am having some troubles over openwrt handeling modem manager and network manager.
Also I realized I bought the modem non version as the factory for dell laptop, the production model I am afraid that I read it is more difficult to flash the firmware.
I would be great if somebody can advise me about the main differences of the firmwares as well being that I am using the generic one firmware, and there is not an specific one for my carrier, that could be also helpful for the next configuration steps. Just trying to find the best config for T-Mobile.

Thank You

2

Hi @peacock

You should be using the PTCRB approved Generic PRI for T-Mobile
https://source.sierrawireless.com/resources/airprime/minicard/74xx/airprime-em_mc74xx-approved-fw-packages/ 34

Please check the PRI (configuration) with
AT!PRIID?
This should read Generic.

Please check the attach state with
AT!GSTATUS?

Please refer to the below topics for more details.
https://lists.freedesktop.org/archives/libqmi-devel/2019-November/003166.html

3

I also wanna to check with you the issues that you may have having one of two versions of this modem, being that they sell the production model and the one that they are selling specific for Dell laptops which I heard is easier to update the firmware, I have the other one… .
One simple question, I read all the instructions about how to update in different sites but which is the command to check which firmware version is running right now this modem?.

Replying to this last user I think the apn may varie a little for T-Mobile depending on the contract you have, being not the same if you have a hotspot or just a regular phone for ex. . I wish already complete the fusion with sprint, and Sierra offers a new firmware for them btw.

4

Hi @peacock

You can use ATI3 and AT!IMPREF? command to check the firmware version and image management preferences modem.

In your case, please contact your reseller or distributor directly for technical support.

5

Did you know in my case connecting my adapter device to an router Openwrt by usb, is it necessary to change the identity of the modem as well? or it is a thing just required to work only with one specific system? I just don’t get the whole point of the use of changing the identity sorry, please let me know

6

There’s no need to change identity.

7

Now I have a new problem I can’t create /dev/ttyUSB*
in usb_modeswitch

Checked this thread related (but so much luck so far):


And also I can’t use storage command, with the error :triumph:
Can’t use storade command in MessageContent with Interface 12; interface class is 2, expected 8.

I tried to change the interface, (current configuration marked as 1 in usb_modeswitch)
Trying to access device 009 in bus 002
and Error: Could no get class of Interface 8. Does it exist?

Did I have to change something with the ID’s to improve my situation
Which for the modem are 1199:9071

Thank you

8

Hi @peacock

For another issue, you should create another new ticket for easy tracking.

9

@peacock since you’re using OpenWRT, check what drivers are being used by the modem.
You could be just missing Qualcomm serial drivers (kmod-usb-serial-qualcomm)

root@openwrt:~#  cat /sys/kernel/debug/usb/devices 

T:  Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  4 Spd=480  MxCh= 0
D:  Ver= 2.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=1199 ProdID=9071 Rev= 0.06
S:  Manufacturer=Sierra Wireless, Incorporated
S:  Product=EM7455B
S:  SerialNumber=**removed**
C:* #Ifs= 4 Cfg#= 1 Atr=a0 MxPwr=500mA
I:* If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=qcserial
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= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=qcserial
E:  Ad=83(I) Atr=03(Int.) MxPS=  10 Ivl=32ms
E:  Ad=82(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= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=qcserial
E:  Ad=85(I) Atr=03(Int.) MxPS=  10 Ivl=32ms
E:  Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 8 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=qmi_wwan
E:  Ad=87(I) Atr=03(Int.) MxPS=   8 Ivl=32ms
E:  Ad=86(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms

You shouldn’t need usb_modeswitch for EM/MC74xx or EM75xx.
I’m using QMI-mode (AT!USBCOMP=1,1,10d) myself so I’m afraid I cannot help with MBIM and ModemManager.

10

I didn’t realice that I had to unblock the com ports first, that is what I am doing right now, otherwise seems I can’t configure the modem either way later on openwrt, or at least do the correct configuration already in linux or windows with the bands open need it and all data to only stablish the conection when I stick my usb on the router. Getting in there… but very tricky this modem…

11

I will try this new apn and will see… so far I didn’t get any succesfully register attempt with Tmobile.
Please comment if some of you guys has the same problem with another carrier or another EM or MC models, thanks