why my bulk device can not work at normal transfer speed without Hub?

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Anonymous
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i'm using cy7c64215 to drive an OLED device with data from PC usb port. but it is very strange if i do not connect my device through a Hub, the transfer speed will be very slow, 1.7Frame/second. however, if i plug it in though a USB Hub, the transfer speed can be 11Frames/second. is this a driver issue or a firmware issue?

   

how to work around?

   

Thank you in advance,

   

BR.

   

jim

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3 Replies
Anonymous
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Are you using our DVK or custom board?

   

Have you hooked up a CATC analyzer to see what is happening on the bus?

   

It could be even signal quality issue where the hub might be having better signal quality. These things you can confirm only by looking at the CATC trace i.e. are packets being dropped.

   

Regards,

   

Anand

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Anonymous
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Thank you Sir, i can make sure it is not a signal issue. i'm sure the driver is sending data in several ms instead of one ms. is there any way to make the driver sending data as quick as it can?

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Anonymous
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 Hi,

   

 

   

  Please take the trace of USB traffic(using USB traffic analyzers like CATC) and post it here so that we can have a look at it.

   

 

   

Thanks

   

Prajith

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