Question about VID/PID & royalties in CDC device

E_Blue · Joined: 13 Apr 2011 Posts: 417

I have two devices that's working ok but I need to change the VID/PID for my owns.

I.E. If I have an USB printer which uses a CDC device to connect to PC and I have an LCD which uses the same CDC library as the USB printer.

I don't see a driver conflict between both because both have a different COM port assigned.

So, the question is, Do I need a new PID for every CDC product?

Thanks.
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Electric Blue

Douglas Kennedy · Joined: 07 Sep 2003 Posts: 755 Location: Florida

Usb VID's are heavily regulated and licensed. I'm not sure but a license if granted may cost as much as $4000. Not a problem if you are a major vendor.

E_Blue · Joined: 13 Apr 2011 Posts: 417

I already have a PID number granted from Microchip, but I don't know if I must to request another if I develop another device which uses the same CDC library.

I'm not talking about cost.
Anyway, is not a matter of being buying licenses just in case, I think.
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Electric Blue

Ttelmah · Joined: 11 Mar 2010 Posts: 19539

This is down to you write your drivers.
Microchip owns it's VID(s).
Inside this range of VID's, it can 'sub let' an individual PID, or range of PID's, to it's customers. With _one_ VID/PID pair, if (for instance), the device(s) on this pair, uses a standard driver, or the driver does not change, then there can be multiple 'different' devices generated on this pair. So you could have a dozen different devices all using the same UART emultion driver, and reported to Windows as "Joe blogg's UART emulation device".
One could be a modem, and another a wired UART, with no problems. _However_ if the Windows driver needs to change, then a new unique VID/PID is _needed_. You can also use a new VID/PID (with the problems that cost will potentially rise), to identify different 'similar' devices. So (for example), I have a few sensors which all use the same library, and the standard Windows CDC driver, but they use different PID's, so the code 'knows' which is a CO2 sensor, which ammonia, etc., from the PID.
So, if your device uses the same library, and the same Windows drivers, and you don't need to identify differences between the devices (or can do this by polling the device), then multiple 'different' devices can have the same VID/PID.
What you mustn't do, is _sell_ a device, using a non standard driver, without having the rights to use the VID/PID pair, or have multiple devices sold using different drivers, on one pair.

Best Wishes