SuperSpeed USBSuperSpeed USBHi-Speed USBOriginal USB
Home > Developers > HID Tools > HID Questions & Answers

HID Questions & Answers

Questions

  1. Why would I want a new Usage or Usage Pages defined assigned by the HID committee?

  2. How do I get a new Usage or Usage Pages defined assigned?

  3. How does the document numbering work?

  4. What is the difference between a Draft 3 and a Draft 4 device?

Answers

1.   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.

1b) If you feel that your new usage fits in one of the existing HID documents then fill out a HID Review Request (RR) form with the appropriate Summary, Background and Proposal information.

The Proposal section of the RR should contain the desired "change text" for the target document.

2) Submit the completed RR to the HID chair. After review by the HID chair a request number will be assigned and the RR will be posted to the HID reflector and this web site. The posting of the RR is not an automatic process. The HID chair filters the requests and reserves right to ask for clarifications and completeness in the RR before posting it.

3) At the next DWG meeting open HID RR's will be discussed and hopefully resolved by the HID working group.

4) After the meeting the RR will be posted to the HID web page.

5) The HID Usage Table document will be updated on an annual basis with all outstanding RRs and those RR will be removed from the HID web page.

3.   How does the document numbering work?

0.6 - The original concept document presented to the HID committee when forming a class working group.

0.7 - Proposal under discussion by the HID committee.

0.8 - DWG Review – posted on the USB-IF/dwgdocs web site.

0.9 - Public review – posted on the USB-IF web site.

1.0 - Final version that vendors can implement to.

Letter suffixes are used to denote intermediate drafts.

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.

In draft 3 the order is:

Configuration
Interface
Endpoint
HID
   

In Draft 4 the order is:

Configuration
Interface
HID
Endpoint

Draft for stated that the class (HID) descriptor immediately follows the associated Interface descriptor.

HID Chair
Nathan C. Sherman
Microsoft Corporation
nathans@microsoft.com