USB oscilloscope / Signal Generator WAS Re: [TLUG]: Where can I buy a linux-friendly laptop?

[Chris Friedt]

Where do I sign up for beta testing ? ;-D

This is exactly what an electrical engineer needs if he or she is about
to sell all of his or her personal belongings & move to a different
country for a few years :)

What are the dimensions of the device ? Does it fit nice & snug in a
laptop carrying case ?

~/Chris

______________________________
Christopher Friedt
Ryerson University
Computing & Communication Services
(416) 979-5000 x6831
chfriedt-0jnyayh6ARPqzrOJbVgLALDks+cytr/Z at public.gmane.org

>>> phiscock-g851W1bGYuGnS0EtXVNi6w at public.gmane.org 11/21/05 10:19:06 pm >>>

(This is a bit of a preview to the TLUG talk on December 13th, in
which
we'll demonstrate new oscilloscope and signal generator hardware using
a
usb-serial device.)

In general, the usb-serial ports appear as /dev/ttyUSB0, /dev/ttyUSB1
and
so on. You simply direct your software to write to that 'serial port'
as
it would to any serial port.

Now, when you first plug in a USB-serial adaptor, the system allocates
one
of these /dev/ttyUSBx devices to it. This is not like a hardware
serial
port, for which the device designation is fixed. The system sees which
/dev/ttyUSBx device is available and allocates that, regardless of
which
hardware USB port you plug in to.

Thereafter (if you are lucky ;) the system remembers that particular
device  and tries to allocate the same pseudo-serial port as
previously.
Obviously this isn't foolproof - if you have two devices that
previously
got /dev/ttyUSB1 and you plug them both in at once, the system gets
confused and you have to select the ports manually.

You can see this at work by running 'dmesg' each time you plug and
unplug
the USB-serial cable. It tells you which port it's allocating to the
device. There is also a program 'usbview' which shows how the usb
system
is configured.

We figured this out by trial and error, not by reverse engineering
code,
so additional or different information may apply...

So to answer William's question, I would bet that you link /dev/modem
to
one of these pseudo-serial ports.

Peter

> If anyone used USB modem successfully, what device do I
> link /dev/modem to?
>
> --
> William Park <opengeometry-FFYn/CNdgSA at public.gmane.org>, Toronto, Canada
> ThinFlash: Linux thin-client on USB key (flash) drive
> 	   http://home.eol.ca/~parkw/thinflash.html 
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> 	  http://freshmeat.net/projects/bashdiff/ 
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-- 
Peter Hiscocks
Professor Emeritus,
Electrical and Computer Engineering,
Ryerson University
416-465-3007
www.ee.ryerson.ca/~phiscock 

--
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TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml
--
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TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml