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dizzy13 04-20-2013 12:56 AM

USB-xover-USB cable -- emulate USB HID -- hardware/driver options?
[ Amazingly the previous QA engineer devised a arduino robot that manipulates the mouse "by hand" as it were. No, it works like you'd expect, but is cool to watch. ]

I need to use a Linux box to operate a second box, a desktop. It needs to operate in two modes. In both modes (this already works) the DVi output of the second box is displayed on the Linux console with annotations.

Mode 1) user uses mouse & keyboard to point click and type into displayed window. Input is captured—only at the level of x,y + button-press-release for the mouse, and key press-release for the keyboard, with millisecond timings—and both recorded to file and forwarded over a USB-USB cable to second box.

Mode 2) previously recorded data is played back either straight, or with dithering of x,y, timings, and possibly alterations to which button is clicked, which key is pressed.

Had been sending data over ethernet and emulating USB directly on the second box, but this only works for a couple subject second boxes (linux, apple).

I can purpose build boxes for this, but the goal is to be able to use anything as a second box and it will just see an ordinary keyboard / mouse (hopefully on a single cable). Well, the goal might be to use a Windows second box without having to touch any windows software.

What is a good USB-USB cable for this? Any limitations on USB chipsets that work for this purpose? Any driver comments?

GlennsPref 04-23-2013 06:13 AM

If you can, in any way possible go with ethernet, far superior (spelling?) throughput. speed/bandwidth/responsivness.

But if tethering or docking devices, rather than a cable, usb-wireless devices may help.

As to what I gather from the question, Been thinking about it...

the physics are, usb up to 2.0(ver)

has 4 wires. 2 data and 2 power.

When connecting 2 powered devices (like 2 pc's) a cross-over type device in required...

so you don't blow a chip from a power missmatch (+>+ on the cable to the chip,) "the smoke comes out and the chip won't work again".

Usually u use a hub, but if neither or only one of the devices is powered, you may communicate with a cross-over cable.

you cross over the data wires and leave the power wires as is. This will stop the powwer frying chips, but may not work with todays pnp tech.

There's plenty of diagrams out there, and usb-2-usb networking has been developed since I started . ;-)

Your project looks interesting...

Cheers, Glenn

michaelk 04-23-2013 08:42 AM

To further elaborate on GlennsPref post, USB works as a master (controller) / slave so regardless of power you can not directly connect two controllers together with regular cables. As stated there are USB data transfer cables which are supported in linux but are typically configured as an ethernet connection (via usbnet).

dizzy13 04-23-2013 10:48 AM

Thank you. Need a special cable because they will both try to master and smoke would ensue. The ethernet I already tried and it's too cumbersome because I'm not doing networking or file transfer, I need to do Mouse/Keyboard.

So I guess the problem is finding an alt to usbnet, or writing my own.

GlennsPref 04-24-2013 09:24 PM

If, ... the units supply power to the usb ports, could you use usb-802. wireless?

Just a guess, been ages since I was at the work bench.

The parts to assemble usb plugs and cable may be bought from the net or your closest city.

Make your own passive x-over box, even with switches to allow one end to be master (!!!Dangerous!!!).

But I'd give the x-o data lines a go, with out power connections.

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