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USB Superspeed Peripherals

New Contributor

We are using the CX3 controller with Sony CMOS imaging chips, but have issues with system crashes when activity takes place on the host PC. I suspect that the problem is caused by using bulk transfers with a device that feeds continuous high speed data (an image stream) - any hesitation in the flow will cause the image data to back up and crash the link. Because of this, we are considering the use of isochronous transfers, but the data rate appears to be lower than with bulk. Is this the case, or is it possible to get maximum bandwidth in iso mode?


Any info. or suggested solutions are welcome!





1 Reply
Not applicable

In Bulk the datarate depends on the bandwidth available with the host. There is no guaranteed throughput. If you use Isoc, you can allocate some fixed bandwidth for your image data transfer. When you configure for Isoc, the throughput depends on what is the burst/mult settings you are provided in the device configuration. 


" data rate appears to be lower than with bulk":  can you clarify what is your burst and mult setting and what is the throughput you get?  What is the throughput you get with Bulk? 


"but have issues with system crashes ": please explain what is the exact behavior which you see. Does your host crash ? What is the data rate required for your video streaming?