USB : USB Classes    A Closer Look at HID Class  

The USB gods at provide a free program called Descriptor Tool that is supposed to help. However, you really need to know all those Report Descriptor rules first in order to be able to use this tool.

That is, you already need to know a whole lot before you can even begin to use the USB Implementers Forum's Descriptor Tool. (After all these years, this Descriptor Tool program is still almost totally undocumented.  This is yet another example of how "free" is not necessarily a bargain...)

The main thing that Descriptor Tool does for you is to turn your human-readable Report Descriptor into the table of numbers that the PC needs to see.

In that sense, using Descriptor Tool is a lot like using assembly language: you still need to understand assembly language in order to be able to write a program in assembler. Once you have written your program, the assembler converts what you wrote into a bunch of numbers which are the actual binary machine language that a processor can actually run.


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