First off, USB 2.0 High Speed signal frequency is about 2GHz IIRC. So
you'll probably want to limit your design to Low-speed (which is what
most HIDs are I think). Secondly, you can't just switch the signals,
or one of the hosts will detect a disconnect. In effect, you have to
make a dummy type device that mimicks your actual device, so that both
hosts think they are connected to the same device at all times.
Have you wondered WHY USB-enabeld KVMs are so expensive?
- Marcel

On 9/11/06, Hop <hop@cableaz.com> wrote:
>
> I have a problem. I bought a KVM from Newegg.com and plugged my new hardw=
are
> into it. Those wonderful new keyboard and mouse devices didn't work with =
it.
> I had this moment of clarity that my shiny new KVM was not compatible with
> my new keyboard and mouse because they use strictly USB. I searched for
> compatible KVM devices and found that they are very expensive.
>
> So, that finally brings me to my point. Knowing that USB is just serial d=
ata
> of a different type than older, outdated keyboard and mouse technologies,=
 I
> should be able to channel that USB connection using a solid-state solutio=
n,
> controlled by an MCU. I should be able to channel that mouse and keyboard
> data to the desired PC.
>
> In the past, I used a CMOS 4066 analog switch as a way to channel digital
> data to different semiconductors. It was a cheap and sleazy way to use a
> low-power solid-state relay if you will. But since USB is digital data, it
> shouldn't be too hard to channel it to a specific PC using a control sign=
al
> from an MCU using logic gates or what have you.
>
> Yeah, it could be done without an MCU, but I want to eventually interpret
> the data from the keyboard and use it to make the switching happen. For n=
ow
> though, I'd be happy using an outside momentary switch to trigger the
> channeling.
>
> What I'm asking for is this. I hit a momentary switch, and my keyboard and
> mouse go to my second machine. I hit it again, and it goes to my primary
> machine, and so on, and so on. I can throw in a couple of LEDs as indicat=
or
> lights to tell me where my keyboard/mouse data is going.
>
> It is nothing different than what a KVM does, minus the video channeling,
> which I don't need in my current setup. I just feel that with all the
> hardware I have available on my workbench that I would rather try building
> it myself. I just don't know if CMOS or TTL is capable of USB 2.0 speeds
> (480 mbps?) and the voltages USB uses to RX/TX data uses. I was hoping
> someone here has an idea of what is needed=85
>
> Can someone recommend a device, hopefully in a DIP package, as I'm not in=
to
> surface mount types yet, that will allow me to use my PIC MCU to control =
USB
> connections?
>
> Thank you all for your time. I can't wait to see this happen. It's for
> home-use BTW. I'm not looking to build the next great KVM. No time for th=
at.
> Lol
>
> Gary (HOP)
> --
> View this message in context: http://www.nabble.com/PIC-controlled-USB-sw=
itch-tf2255581.html#a6256209
> Sent from the MicroControllers - PIC forum at Nabble.com.
>
>
> --
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> http://mailman.mit.edu/mailman/listinfo/piclist
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