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Controlling the USB Transfer size | Cypress Semiconductor

Controlling the USB Transfer size

Summary: 1 Reply, Latest post by Chris R. on 06 Feb 2012 12:43 PM PST
Verified Answers: 0
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TimC's picture
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how is the USB transfer size controlled through the FX3 API?

Do I understand correctly, that when using bulk transfers, packet size 1024 and 16x burst, the transfer size is always 16K? How can I increase it?

Can I increase it without having all the data available up front in a single buffer (but knowing it will stream in later)?

I searched the documentation and was not able to find anything pointing me at the USB transfer size.

Thank you


Chris R.'s picture
143 posts

Yes, in SuperSpeed mode the USB host can handle up to 16 packets with each 1024 byte in one chunk. But this is on driver level. On user level in Windows you can use larger transfer sizes. You can request for example 1MB data from the driver and the USB driver collect all the data if available. On FX3 side you can increase performance using multiple DMA buffers, default is 2 buffers. The FX3 can switch between the buffers very fast.

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