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So the system of USB VID/PIDs as far as I understand it is to avoid conflicts between devices and the USB-IF is handling the distribution of these IDs and wants a fee if you need a VID and a corresponding PID block.

Now how is the situation looking if you have an enclosed device where systems within that device talk via USB but the device itself does not expose a USB port or advertise USB compliance or the use of USB in any way, it is just used for internal communication like you would use SPI or I2C.

Do I still need a VID/PID from the USB-IF? If yes is it allowed to then just use the prototype VID 6666?

The USB Host device in this system is running Linux. So a driver is in use, the end user just can't plug in any more USB devices to this host. I have the ability to chose the VID for every device connected to avoid any conflict.

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    \$\begingroup\$ Is this an EE question? \$\endgroup\$ – Andy aka Aug 10 '17 at 11:15
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    \$\begingroup\$ It is not necessary to have a unique VID or even a unique PID in order to avoid conflicts. Otherwise identical devices, in order to avoid a conflict, would report a different serial number to the host. This is how you can have identical USB to serial converters plugged into a PC and always get the same COM number for a given converter. \$\endgroup\$ – Tut Aug 10 '17 at 11:24
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    \$\begingroup\$ @Andy, Yes it is. \$\endgroup\$ – Jeanne Pindar Aug 10 '17 at 12:51
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It will work, if that's what you're asking. And there is no law saying you must buy a VID from the USB-IF in order to use USB - you only get in trouble if you use the name and logo without permission. Some things to consider:

  • If you do want to insert a computer, to do debugging or something, life will be easier if you have a unique VID/PID combo and can write drivers accordingly.
  • At some point one of your customers will take the product apart and, if they see a USB port inside, plug it into a computer. They shouldn't have any drivers for that VID, but they might. You'll want to make sure that can't damage anything, or just stick a "warranty void if opened" sticker on it.
  • The same is true if the user can plug random hardware into the USB host within the device. They shouldn't have any hardware with that VID, but they might. And you don't want the host to brick that hardware by accident. If there are no external USB ports, then the warranty void sticker works here too.
  • Some dodgy USB sticks and other cheap clone devices use VID=6666 and PID=8888, and maybe others. It's probably worth checking and avoiding those PIDs.
  • You can buy single PIDs from MCS electronics for about $15. The USB-IF do not approve, but legally it seems they cannot stop it. Some manufacturers of USB hardware also give out PIDs from their VID.

That said, I'd probably just do what you propose, and use VID=6666 with some random (i.e. not 1111 or BEEF etc) PID which doesn't have any google hits.

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No, you don't need a unique VID/PID. These parameters are used by the OS to load the correct driver for the device. If you don't need a driver, you don't need these parameters.

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  • \$\begingroup\$ Sort of like not needing a driver's license if you never get into your car? \$\endgroup\$ – Scott Seidman Aug 10 '17 at 11:12
  • \$\begingroup\$ I do need a driver as the USB host in this scenario is a system running the Linux kernel. I edited the answer to reflect that. \$\endgroup\$ – PTS Aug 10 '17 at 11:14
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    \$\begingroup\$ @ScottSeidman, like not needing a driver's licence if you only drive on your own land. \$\endgroup\$ – Simon Richter Aug 10 '17 at 11:30
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If any of the following are true:

  • your internal use of the USB bus needs to be certified compliant with the USB specification
  • you need to use the logo and/or other trademarks associated with the USB standard
  • you want your device/host to work with 3rd party USB devices

Then yes, you will need to comply with the VID/PID requirements as well.

If all three are false then you can use whatever VID/PID you want that will meet your project requirements.

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  • \$\begingroup\$ Is the first and third point legally speaking or about ensuring correct functionality? \$\endgroup\$ – PTS Aug 11 '17 at 21:02
  • \$\begingroup\$ @PTS They are all interrelated. Technically only the middle point has any legal teeth. You can't use the trademarks (such as the work "USB" or the logos) without also being compliant and ensuring interoperability with other USB devices. \$\endgroup\$ – Adam Davis Aug 11 '17 at 21:05

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