USB Hub


9 posts
by woodygar@sky.com » Mon Dec 19, 2011 11:08 pm
Hi

I know it hasn\'t been released yet but will i be able to use the same keyboard, mouse and Monitor as my regular desktop without plugging and unplugging leads. Sorry if this sounds lazy. I was just wondering if a USB HUB is enough to recognise when the main tower is switched off and work with Pi accordingly.

Thanks
Posts: 2
Joined: Thu Dec 08, 2011 6:34 pm
by Tomo2k » Mon Dec 19, 2011 11:55 pm
Normal USB hubs don\'t work like that.

You want a \"KVM\" switch - these are available at various price points and with various features.

Automatic switching versions are quite expensive (and not as useful as you might think), however there are a lot of cheap ones that have \'manual\' A/B switches on them - hit a button to flip over to the \'other\' machine.
Posts: 126
Joined: Mon Dec 19, 2011 10:00 pm
by mobeyduck » Tue Dec 20, 2011 12:18 am
If you can find a hub with a real short cable you can use two usb extension cables one coming from the Pi one from your PC that\'s the easiest way.

You could also mod a hub as in making it get 2 usb cables one from the pc one from the R-Pi but this could get you some trouble with the power

So basicly, no not really possible a KVM (Keyboard Video Mouse) switch is best for hdmi you would end up on some thing like this [url]http://www.aten.com/products/productItem.php?model_no=CS1792[/url] €131

If you have a monitor with multiple video in you could get one of these and just dont connect the vga to the pi [url]http://www.ebay.com/itm/USB-2-0-KVM-Switch-BOX-Video-Monitor-VGA-SVGA-2-Port-/300639007985?pt=COMP_EN_Networking_Components&hash=item45ff7b34f1[/url] then you can switch the keyboard and mouse
A little side note, i have no clue if the additional buttons from your mouse (forward/back/increase DPI) will be supported by any kvm
Posts: 173
Joined: Tue Nov 29, 2011 6:39 pm
by RaTTuS » Tue Dec 20, 2011 12:12 pm
see also synergy+ http://code.google.com/p/synergy-plus/
1QC43qbL5FySu2Pi51vGqKqxy3UiJgukSX - Prosliver FTW
"That's not right, the badgers have moved the goalposts."
User avatar
Posts: 4671
Joined: Tue Nov 29, 2011 11:12 am
Location: North West UK
by woodygar@sky.com » Tue Dec 20, 2011 1:21 pm
Thanks a bunch, looks like i need a Kvm switch. The monitor im using has a VGA and DVI connection so am i right in thinking no problem using the USB VGA switch.
Posts: 2
Joined: Thu Dec 08, 2011 6:34 pm
by wrhii » Tue Dec 20, 2011 1:25 pm
Biggest challenge for using any sort of KVM is that it will have to be a DVI connection most likely, and those can get somewhat pricey. Not impossible, just runs several bucks.
[url=http://goo.gl/C8LjO]Amazon[/url] has some for !$125... Which is a hefty chunk of change.

If you don\'t [i]really[/i] need to see the display, and can work via telnet, or some sort of Remote Console connection you can save a ton. Otherwise, swapping some cables is likely to be the cheaper route.
Posts: 66
Joined: Fri Nov 18, 2011 1:47 am
by sylvan » Tue Dec 20, 2011 10:23 pm
[quote][b]Quote from wrhii on December 20, 2011, 13:25[/b]
Biggest challenge for using any sort of KVM is that it will have to be a DVI connection most likely, and those can get somewhat pricey. Not impossible, just runs several bucks.[/quote]

Or you do as the previous poster mentioned... Use the KVM to switch K.M and use the monitor buttons to select which monitor V input is displayed.
Posts: 115
Joined: Sun Nov 27, 2011 8:39 pm
by Burngate » Wed Dec 21, 2011 11:04 am
It [i]might[/i] be possible to use a standard KVM switch, by sending the HDMI data through the VGA ports. It would require cutting the HDMI plugs off the cables and replacing them with D15 plugs, and would depend on the quality of the switches in the KVM. Worth trying if you already have a switch, not worth it if you have to spend money.
Brain surgery is easier than psychoanalysis
User avatar
Posts: 2662
Joined: Thu Sep 29, 2011 4:34 pm
Location: Berkshire UK
by sylvan » Thu Dec 22, 2011 7:54 pm
It \"might\" but I think it very unlikely. Electronic KVMs only switch a few of the video signals (not all 15 pins) and try to pass thru EDID unmolested. In addition since they typically use electronic instead of mechanical switches they have constrained bandwidth (affecting rise/fall times of the signals being passed). Since HDMI signals and EDID are very different from VGA I for sure won\'t be butchering any cables on the slim chance a VGA KVM would work.

The chances may be slightly higher if you have an old-style mechanical KVM. But you\'ll have to tear it apart and trace which pins are actually switched.

Oh, and while you may find VGA<>DVI and DVI<>HDMI adapters out there, they won\'t chain together to make this work. DVI<>HDMI are the same digital signals, just a different connector. And VGA<>DVI are the same analog VGA signals just a different connector. But the analog VGA signals are not on the same DVI pins as the digital HDMI signals so you\'ll get nothing by chaining them together.
Posts: 115
Joined: Sun Nov 27, 2011 8:39 pm