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fandevicefw/usbdrv/USB-ID-FAQ.txt

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+Version 2012-07-09
+
+==========================
+WHY DO WE NEED THESE IDs?
+==========================
+
+USB is more than a low level protocol for data transport. It also defines a
+common set of requests which must be understood by all devices. And as part
+of these common requests, the specification defines data structures, the
+USB Descriptors, which are used to describe the properties of the device.
+
+From the perspective of an operating system, it is therefore possible to find
+out basic properties of a device (such as e.g. the manufacturer and the name
+of the device) without a device-specific driver. This is essential because
+the operating system can choose a driver to load based on this information
+(Plug-And-Play).
+
+Among the most important properties in the Device Descriptor are the USB
+Vendor- and Product-ID. Both are 16 bit integers. The most simple form of
+driver matching is based on these IDs. The driver announces the Vendor- and
+Product-IDs of the devices it can handle and the operating system loads the
+appropriate driver when the device is connected.
+
+It is obvious that this technique only works if the pair Vendor- plus
+Product-ID is unique: Only devices which require the same driver can have the
+same pair of IDs.
+
+
+=====================================================
+HOW DOES THE USB STANDARD ENSURE THAT IDs ARE UNIQUE?
+=====================================================
+
+Since it is so important that USB IDs are unique, the USB Implementers Forum,
+Inc. (usb.org) needs a way to enforce this legally. It is not forbidden by
+law to build a device and assign it any random numbers as IDs. Usb.org
+therefore needs an agreement to regulate the use of USB IDs. The agreement
+binds only parties who agreed to it, of course. Everybody else is free to use
+any numbers for their IDs.
+
+So how can usb.org ensure that every manufacturer of USB devices enters into
+an agreement with them? They do it via trademark licensing. Usb.org has
+registered the trademark "USB", all associated logos and related terms. If
+you want to put an USB logo on your product or claim that it is USB
+compliant, you must license these trademarks from usb.org. And this is where
+you enter into an agreement. See the "USB-IF Trademark License Agreement and
+Usage Guidelines for the USB-IF Logo" at
+http://www.usb.org/developers/logo_license/.
+
+Licensing the USB trademarks requires that you buy a USB Vendor-ID from
+usb.org (one-time fee of ca. 2,000 USD), that you become a member of usb.org
+(yearly fee of ca. 4,000 USD) and that you meet all the technical
+specifications from the USB spec.
+
+This means that most hobbyists and small companies will never be able to
+become USB compliant, just because membership is so expensive. And you can't
+be compliant with a driver based on V-USB anyway, because the AVR's port pins
+don't meet the electrical specifications for USB. So, in principle, all
+hobbyists and small companies are free to choose any random numbers for their
+IDs. They have nothing to lose...
+
+There is one exception worth noting, though: If you use a sub-component which
+implements USB, the vendor of the sub-components may guarantee USB
+compliance. This might apply to some or all of FTDI's solutions.
+
+
+=======================================================================
+WHY SHOULD YOU OBTAIN USB IDs EVEN IF YOU DON'T LICENSE USB TRADEMARKS?
+=======================================================================
+
+You have learned in the previous section that you are free to choose any
+numbers for your IDs anyway. So why not do exactly this? There is still the
+technical issue. If you choose IDs which are already in use by somebody else,
+operating systems will load the wrong drivers and your device won't work.
+Even if you choose IDs which are not currently in use, they may be in use in
+the next version of the operating system or even after an automatic update.
+
+So what you need is a pair of Vendor- and Product-IDs for which you have the
+guarantee that no USB compliant product uses them. This implies that no
+operating system will ever ship with drivers responsible for these IDs.
+
+
+==============================================
+HOW DOES OBJECTIVE DEVELOPMENT HANDLE USB IDs?
+==============================================
+
+Objective Development gives away pairs of USB-IDs with their V-USB licenses.
+In order to ensure that these IDs are unique, Objective Development has an
+agreement with the company/person who has bought the USB Vendor-ID from
+usb.org. This agreement ensures that a range of USB Product-IDs is reserved
+for assignment by Objective Development and that the owner of the Vendor-ID
+won't give it to anybody else.
+
+This means that you have to trust three parties to ensure uniqueness of
+your IDs:
+
+  - Objective Development, that they don't give the same PID to more than
+    one person.
+  - The owner of the Vendor-ID that they don't assign PIDs from the range
+    assigned to Objective Development to anybody else.
+  - Usb.org that they don't assign the same Vendor-ID a second time.
+
+
+==================================
+WHO IS THE OWNER OF THE VENDOR-ID?
+==================================
+
+Objective Development has obtained ranges of USB Product-IDs under two
+Vendor-IDs: Under Vendor-ID 5824 from Wouter van Ooijen (Van Ooijen
+Technische Informatica, www.voti.nl) and under Vendor-ID 8352 from Jason
+Kotzin (now flirc.tv, Inc.). Both VID owners have received their Vendor-ID
+directly from usb.org.
+
+
+=========================================================================
+CAN I USE USB-IDs FROM OBJECTIVE DEVELOPMENT WITH OTHER DRIVERS/HARDWARE?
+=========================================================================
+
+The short answer is: Yes. All you get is a guarantee that the IDs are never
+assigned to anybody else. What more do you need?
+
+
+============================
+WHAT ABOUT SHARED ID PAIRS?
+============================
+
+Objective Development has reserved some PID/VID pairs for shared use. You
+have no guarantee of uniqueness for them, except that no USB compliant device
+uses them. In order to avoid technical problems, we must ensure that all
+devices with the same pair of IDs use the same driver on kernel level. For
+details, see the file USB-IDs-for-free.txt.
+
+
+======================================================
+I HAVE HEARD THAT SUB-LICENSING OF USB-IDs IS ILLEGAL?
+======================================================
+
+A 16 bit integer number cannot be protected by copyright laws. It is not
+sufficiently complex. And since none of the parties involved entered into the
+USB-IF Trademark License Agreement, we are not bound by this agreement. So
+there is no reason why it should be illegal to sub-license USB-IDs.
+
+
+=============================================
+WHO IS LIABLE IF THERE ARE INCOMPATIBILITIES?
+=============================================
+
+Objective Development disclaims all liabilities which might arise from the
+assignment of IDs. If you guarantee product features to your customers
+without proper disclaimer, YOU are liable for that.