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USB 3.0 descriptor definition | Cypress Semiconductor

USB 3.0 descriptor definition

Summary: 3 Replies, Latest post by RobK on 13 Apr 2015 04:51 AM PDT
Verified Answers: 1
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sksno1's picture
27 posts


I use FX3s eveluation board to study USB 3.0 spec, But I have some wonder about  descriptors.

I think kind of ordering problem, but I can't understanding cleary.

USB 3.0 Specification Release Number for example, in Device descriptor. the Number is 0x0300 but in the example code(USBBulkLoopAutoEnum Descriptor) is written 0x0003. 

another sample is Vendor ID, I know Cypress Semiconductor Vendor ID is 0x04B4, but example code served 0xB404.

By ther way,  Product ID is different, CY30700 Licorice evaluation board product number is 0xF000, example coude served 0xF000.

What is different thing about Product ID and Vendor ID or Specification Release Number ??





qiang_qiang's picture
7 posts

 Hello. I also find the issue but I don't think we need to change the values of the descriptor so I just ignore it. The descriptor is then passed to the function CyU3PUsbSetDesc, maybe the ordering is changed in the function.

sksno1's picture
27 posts

 Thank you for your reply

Have a nice day

RobK's picture
81 posts


the descriptors have to defined in little-endian byte-order. Therefore the least significant byte comes first and the most significant byte comes last.



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