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HID Questions & AnswersQuestions
Answers1. Why would I want a new Usage or Usage Pages defined assigned by the HID committee? If a group of companies wants to do some level of standardization of command sets for a common line of products then it appropriate to ask the HID committee for Usage or Usage Page assignments. The process starts with a 0.7 document generated by the interested companies, which lists and describes the desired usages. See the USB HID Usage Tables document for an example of the format and content that are required. If a vendor intends to always supply their own application software with their device then there is really no need to obtain Usage Pages or Usages from the HID committee. A vendor can take full advantage of all HID features and the operating system supplied HID drivers using Vendor Defined usages. The HID Class committee and subcommittees work as a consortium of companies that have common interests. A single company can propose a new Usage Page or new Usages for a particular product, however before the group can sanction the work of that company, that work must be reviewed, understood and agreed to by at least one other company with a similar product line. We must present to the public at large, the results of cooperation among companies that produce similar products. This approach assures that we remain objective and unbiased. 2. How do I get a new Usage or Usage Pages defined assigned? It depends on the scope of the desired additions. 1a) If you are looking at a new subclass of HID class devices then a separate document like the Monitor or Power class documents is appropriate. This requires the generation of a 0.7 version of the document that is submitted to the chair of the HID committee. This will be attached to a HID Review Request (RR) form which will ask for one or more usage pages to be assigned in the USB Usage Tables document. 3. How does the document numbering work? 0.6 - The original concept document presented to the HID committee when forming a class working group. A Release Candidate of a document may be issued just prior to release of a new major revision, if there have been significant changes from the prior document, but no more are expected before we go to that next level. The release candidate is used to make sure that all of the changes have been captured correctly. A release candidate will have a ‘rcn’ suffix where n is the release candidate number. 4. What is the difference between a Draft 3 and a Draft 4 device? All current devices should be Draft 4 compliant (which is the same as HID 1.0 compliant). The difference between a draft 3 and 4 device is the ordering of the returned descriptors when a GetDescriptor(Configuration) command is issued to the device.
Draft for stated that the class (HID) descriptor immediately follows the associated Interface descriptor. HID Chair |
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