Libusb needs exclusive access to device?

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Libusb needs exclusive access to device?

by Kai Parow-Souchon :: Rate this Message:

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Hey!

we're currently planing to give a device a few new features and
therefore we need to know whether two different libusb programs can
connect to the same USB-device.

If not (what i expect ) our way would be to make a composite device,
which would be splitted by the usbccgpd to 2 devices on the pc, so the
pc-software could connect to each of the device.
That's possible, isn't it? ;)

Thanks,
Kai

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Re: Libusb needs exclusive access to device?

by Alan Stern :: Rate this Message:

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On Thu, 5 Nov 2009, Kai Parow-Souchon wrote:

> Hey!
>
> we're currently planing to give a device a few new features and
> therefore we need to know whether two different libusb programs can
> connect to the same USB-device.

Yes, they can (under Linux anyway).  But the two programs cannot
communicate with endpoints in the same interface; each program has to
claim the interface it will use.

> If not (what i expect ) our way would be to make a composite device,
> which would be splitted by the usbccgpd to 2 devices on the pc, so the
> pc-software could connect to each of the device.
> That's possible, isn't it? ;)

I've never heard of usbccgpd before, but it does sound possible.

Alan Stern


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Re: Libusb needs exclusive access to device?

by Tim Roberts :: Rate this Message:

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Alan Stern wrote:

> On Thu, 5 Nov 2009, Kai Parow-Souchon wrote:
>  
>> If not (what i expect ) our way would be to make a composite device,
>> which would be splitted by the usbccgpd to 2 devices on the pc, so the
>> pc-software could connect to each of the device.
>> That's possible, isn't it? ;)
>>    
>
> I've never heard of usbccgpd before, but it does sound possible.
>  

Usbccgp.sys is the Windows generic driver for USB composite devices, if
you don't handle the composite yourself.  It makes the interfaces look
like separate devices so they can be handled by independent drivers.

CCGP stands for "Common Class Generic Parent",

--
Tim Roberts, timr@...
Providenza & Boekelheide, Inc.


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