Dialing uknown usb modems

[roeek]

hello everyone, i have a crazy question, i don't sure if it's possible. but anyway - my purpose here is not only to get an answer of yes/no, but really understand what's behind.

i have all kinds of usb cellular modems i want to try.
i used 2 models of the sierra wireless modem, and one ZTE modem. when i connect the usb modem, i see /dev/ttyUSB* (1/2/3..).
then, using minicom i can connect to the device and send AT Commands to communicate with it.

when i tried another modem, which is not recognized by NetworkManager for example, i couldn't see any /dev/ttyUSB*, and i have no idea how can i send data to the device..

my question is:
1) what's the driver role in creating those ttyUSB handles?
2) how can i just write to the usb device, the same like in serial ports for example?
3) so, if i were the best developer in the world, is it possible to communicate with an unknown usb modem? or in any case - i'm depended on the manufacturer driver?

thanks.

[Djhg2000]

hello everyone, i have a crazy question, i don't sure if it's possible. but anyway - my purpose here is not only to get an answer of yes/no, but really understand what's behind.

i have all kinds of usb cellular modems i want to try.
i used 2 models of the sierra wireless modem, and one ZTE modem. when i connect the usb modem, i see /dev/ttyUSB* (1/2/3..).
then, using minicom i can connect to the device and send AT Commands to communicate with it.

when i tried another modem, which is not recognized by NetworkManager for example, i couldn't see any /dev/ttyUSB*, and i have no idea how can i send data to the device..

my question is:
1) what's the driver role in creating those ttyUSB handles?
2) how can i just write to the usb device, the same like in serial ports for example?
3) so, if i were the best developer in the world, is it possible to communicate with an unknown usb modem? or in any case - i'm depended on the manufacturer driver?

thanks.

This thread seemed so lonely and I had some time to kill (waiting for class to start) so I tried to give you some semi-accurate answers, mostly from my memory:

1) No idea.
2) There should be a way to send raw USB packets to a specific device, probably through /dev/bus/usb/[bus]/[device] , but I've never tried it myself.
3) I guess you could sniff the USB traffic within some OS it works with (Windows maybe?) and reverse engineer the protocol, otherwise you would probably need documentation to get started. Then again, I've never done it myself but I do follow the development process of drivers I find interesting, so it's probably not 100% accurate but you get the general idea.

[unlimitedscolobb]

my question is:
1) what's the driver role in creating those ttyUSB handles?
2) how can i just write to the usb device, the same like in serial ports for example?
3) so, if i were the best developer in the world, is it possible to communicate with an unknown usb modem? or in any case - i'm depended on the manufacturer driver?

It looks like the driver may create the character-special device files, but I am not sure as to that. What I pretty sure about (have read about it somewhere recently) is that the main problem with USB modems is the proprietary firmware a driver has to upload to the modem. This means that unless you have the firmware, you cannot initialize the modem and thus you cannot work with it, however good you were at programming.