Hi Cyril,

I am also interested in building my own applications into a self-contained unit, so would be keen to collaborate with you on this. My target is a D-Link DWM222-A2 LTE dongle. Is your module based on the same MDM9625 core, or something else?

Regards,

Rogan

On Fri, 22 Jan 2021 at 12:54, Cyril HAENEL chaenel@free.fr wrote:

Hello, my name is Cyril HAENEL, and I am new on this mailing list :) I subscribed to this list because I was looking for informations on Quectel LTE modem, and yesterday I found this fantastic video : https://media.ccc.de/v/33c3-8151-dissecting_modern_3g_4g_cellular_modems#t=6...

I actually work on the Quectel LTE SC20 Smart module, which is proposed with Android, but also Linux without all Android layers. We want to use the Linux version and we use the official Quectel Linux SDK, based on Yocto.

We can successfully build and flash the image in the module, no problem from this side.

But the goal of this module is not to be used just as an LTE modem for an external host, it's a standalone module and we embed our IoT application inside.

The problem we are facing is that we don't know how to start a broadband connection !! There is absolutely no Quectel documentation about that, and their support is really bad, they don't help us at all...

So we done some reverse engineering to understand how the internal Modem is connected to main processor, how to send him AT command, how to start data connection, etc... We finally found and understood all methods they use (Shared Memory Devices, qmuxd, qmi proxy, QMI protocol, etc.....).

But we are stuck to the same point, we don't find any easy way with scripts or some utilities with config file (to set the APN for example) to start a broadband connection :(

We flashed an Android version in the SC20 to see how it works, and they have Android applications which connect to netmgrd, qmuxd, etc.... But we don't have these tools under Yocto Linux, so we wondering how we can easily set our broadband connection.

Any help or comment will be great :)

Best regards, Cyril

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Cyril Haenel Registered Linux User #332632

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Hi Cyril,

good to hear from you and your experience.

I myself unfortunately have never worked on the (much more complex) "smart" Quectel modems (SCxx), just on the regular ECxx series.

It's indeed quite odd that they provide a "plain Linux" yocto based SDK but then have no information whatsoever on how to talk to the modem ;)

Maybe the people behind https://github.com/bacnh85/Docker_Quectel_SC20_Linux have an idea?

I would normally expect that there is either some way to access AT commands, or to access QMI. Once you reach either of the two, you can then use ofono, modemmanager or the like.