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UVC example with ISOC endpoint over USB3.0
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UVC example with ISOC endpoint over USB3.0

shah posted on 28 Sep 2012 6:10 PM PST
Cypress Employee
9 Forum Posts

AN75779 uses USB bulk endpoint to transfer image data. The total available bandwidth would be around 40MBps over USB2.0 and 400MBps over USB3.0 since it is bulk implementation. If this is changed to isoc, the total available bandwidth will be limited to 24MBps over USB2.0 and 128MBps over USB3.0. I have tried alocating more bandwidth with isoc endpoint in USB3.0 and the host does not allow it today.

However, the standard UVC driver has not been updated for USB3.0. It allows the bulk implementation to set a burst length of 16 but it does not allow the isoc implementation to set a mult higher than 1 or burst of larger than 1. This pretty much limits the bandwidth to 8MBps over USB3.0 and is not very useful.

Testing OS: XP 32bit, Vista 64bit, Win7 64bit

Conclusion: For standard UVC applications over USB3.0, bulk is the way to go.







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