[TriLUG] USB communication

[Tim Jowers via TriLUG]

And this may not help at all but some samsung devices such as note II have
a host mode which may be turned on by a config file in /etc somewhere. You
can root the device perhaps and maybe do something you want with the phone
as a host or not. What the "not" is I guess is the question. I guess its a
"device".

Cheers,
Tim


On Tue, Oct 25, 2016 at 11:24 AM, Brian via TriLUG <trilug at trilug.org>
wrote:

> Seems like my reply from work is stuck in limbo...so:
>
> Hi Brian,
>
> I have some thoughts that may be helpful.
>
> As you probably already know, at a given moment, a USB-connected device is
> either a "host" or a "device".  In all cases that I'm aware of, Type-A
> ports (such as on your computer) are always Host ports, and all other ports
> (with the exception of Micro-AB) are Device ports.  This is by design.  The
> exception is the Micro-AB port, which is the only port which supports the
> USB On The Go (OTG) spec, allowing a Device to behave as a Host (e.g.
> plugging a camera into a phone).
>
> lsusb will never show you the "input" port because you have a case of
> Host-Host, which just doesn't work.  In order for the host PC to send USB
> packets to the widget, the widget *must* present itself as a device to the
> PC.  In other words, the widget must behave differently (because it is in a
> different role in the USB protocol).
>
> If this is an off-the-shelf widget of some sort, you'll have to get a
> third doohickey (technical term) to allow your PC to pretend to be a device
> (which it can't do on its own and be in spec).  This third doohickey would
> look like a device to both hosts: it would implement the HID spec for mouse
> for the widget, and probably act as a serial port to the host PC.
>
> Where to get that doohickey, other than cobbling one up yourself with, for
> example, an Arduino and an FTDI USB-serial chip, I can't say.
>
> Glad to assist further if you've got questions.
>
> -Brian
>
>
>
>
>
> On 10/24/2016 02:52 PM, Brian McCullough via TriLUG wrote:
>
>> Folks,
>>
>> I am working on a new project, started last week, and am running into
>> some questions.
>>
>> Not having much experience with USB hardware or the programming thereof,
>> I am likely not either asking the right questions or understanding what
>> I am finding.
>>
>>
>>
>> I am attempting to create a sort of test rig, using my laptop, for a
>> device that has two USB ports.
>>
>> One of the ports expects to have a WiFi dongle plugged in, attached to a
>> wireless mouse, and the other has a cable attached to a computer, acting
>> as the same wireless mouse to that computer.
>>
>> What I would like to do is to plug a cable from the first port to a USB
>> port on my laptop, and a second cable from the second port to a second
>> port on the same laptop.
>>
>> The goal is to send a signal to the "input" port and measure that signal
>> coming out of the "output" port. ( the codes that the mouse sends to the
>> computer )
>>
>> When I plug this device into my laptop, I do see the "output" port
>> appearing in lsusb, but not the "input" port.  I am obviously missing
>> something, and need some guidance which may include a primer on how to
>> make all of this work.
>>
>> My intent was to use what I have read, in the way of documentation and
>> example code, to write a program in Python, using the PyUSB library, to
>> generate the "input" codes and read the "output" result, comparing them.
>>
>> However, if I can't send the "input" codes to the device, that plan has
>> a small flaw.
>>
>>
>>
>> Any suggestions, help, pointers to How-Tos?
>>
>>
>> Thanks,
>> Brian  ( the other one! )
>>
>>
>>
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