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some questions about fx3 | Cypress Semiconductor

some questions about fx3

Summary: 1 Reply, Latest post by RSKV on 02 Feb 2014 02:21 AM PST
Verified Answers: 0
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user_253581985's picture
14 posts

question1 as following picture     Data An  where come from??(where ?1  in the picture.)

question1 as following picture     Data is uping to the bus ,why the fifo addr is the same ?   (where ?2 in the picture.)



2    in the article   An65974  page22   : 5. sets up the DMA channels  

a. For loopback transfers, short packet, and ZLP transfer, two DMA channels are created:   why the buffer =1kB  ? (for usb 3.0)

b. For streaming, two DMA channels are created:  the buffer =16KB?  (for usb 3.0)    what is difference between the 1kB and 16 kB?


rskv's picture
Cypress Employee
1134 posts

 Hi Chujun,

The reason why we have two different buffer sizes is as follows:

Stream IN and stream OUT are intended to show the through put numbers. So we are using multiple buffers of 16KB.

Whereas in the loopback, short packet and the ZLP cases, the intention is to just show the functionality. That is the reason why we used only 1KB size buffers. You can also have 16KB assigner for example in loopback case. But the problem is that you need to transfer 16KB of data from the USB host to the FX3 endpoint to get it looped. If it is a 1KB buffer then it will be easy for you to verify the loopback operation.


Sai Krishna.

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