# ttyUSB missing

## Jaglover

I'm trying to use my cell phone as a modem and ttyUSB device is not created. What kernel options have to be enabled to make ttyUSB available?

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## khayyam

Jaglover ...

I believe that would be CONFIG_USB_SERIAL, and either one or other of the USB_SERIAL dirvers or CONFIG_USB_SERIAL_GENERIC.

see ... Documentation/usb/usb-serial.txt

HTH & best ... khay

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## Jaglover

Thanks for reply. That's what I thought. But no joy ... 

http://bpaste.net/show/92802/

... then I discovered loading moto_modem and cdc-acm modules create ttyACM0 node ... which actually allows me to use my Motorola cell phone as a modem.   :Rolling Eyes: 

So I really should not be complaining, but then again, I would like to know what the heck I'm doing here?

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## khayyam

 *Jaglover wrote:*   

> ... then I discovered loading moto_modem and cdc-acm modules create ttyACM0 node ... which actually allows me to use my Motorola cell phone as a modem.

 

Jaglover .. ok, so USB_SERIAL_MOTOROLA ...

 *Jaglover wrote:*   

> So I really should not be complaining, but then again, I would like to know what the heck I'm doing here?

 

Modems (modulator-demodulator) use a serial line with a command set for speaking to a device, normally things like 'AT+' so, similar to the method for dialing a number using an analogue phone. In the good old bad old days this was the method of getting a "dialup" line, normaly to a BBS, or perhaps ISP. The technology has moved on since then but the principles haven't, in your case your probably using ppp to have the phone act as a modem, and so modulate-demodulate a signal over GSM ... at least something like that ... I'm having a nostalgia trip .... phewww 2600 baud, slow down there!

Your using a tty because thats what the whole thing developed from, teleprinter, teletype, or tty, a text based interface to mainframe computers, often via telephone circuits. These tty's were used to input code that was then sent to a mainframe to process, the mainframe would then send back the output in the form of a printout. These tty's have now been replaced with the display, but at one time it was string of punched tape, still, all the terminology is still still with us, in the form of ttyACM0, etc.

Hopefully that makes things a little clearer ... best ... khay

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