When is a VID and PID required?

[hawk]

Hi,

First of all, thanks for this site and the great books.

We're adding USB communication between a custom PC application and several
devices and are trying to determine if it's necessary to obtain a VID and PID.
We plan to enumerate the devices as Vendor-Specific and use the WinUSB driver.
The discussion of the idVendor member of the device descriptor in USB Complete
indicates that, for devices used only in house, the VID may not be required.
We want the devices to be PnP. I know we need to provide a .inf file for the
devices but do we need VID and PID in order to have PnP and device discovery?

Thanks

[Jan Axelson]

For WinUSB, you need an INF file that contains a GUID and a VID and PID. If you're keeping the device in house, the VID/PID can be any values that don't match the VID/PIDs in other INF files on your system.

Also see:

http://www.lvr.com/development_tools.htm#vendor_id

Jan

[Ron Hemphill]

I don't remember the discussion in USB Complete, but Jan also discusses it here:
http://www.lvr.com/development_tools.htm

Basically, if you know that you're never going to release the device to the public, then you probably don't need to have a VID (Jan even allows researchers to use her VID in these cases, see the link above).  Windows (and I'm assuming Windows only because you mention PnP), or any other OS for that matter, generally don't care which VID is used unless it happens to conflict with some other device on the system and as long as it can find the matching VID in the .inf file.

Also, some USB chip vendors allow use of their VID with assigned (by them) PIDs in certain cases on products using their chips.  This is very manufacturer dependent and you'd have to check directly with them.

In a nutshell, if you plan to market this device, you really do need your own VID.
http://www.usb.org/developers/vendor/

[hawk]

Thanks Jan and Ron. Very helpful.