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| Author | Topic: USB Transfer Interval |
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oscillo New Member |
posted August 11, 2010 01:07 AM
 
Hi All, Currently, I'm using the USB_HID Mouse sample code(C8051F34x) to do a testing on C8051F34x Dev Kit. I have tried to use a Software called Bus Hound to monitor the data transfer from C8051F34x Dev Kit to PC through USB. I had discovered that the elapsed time(delta) for each packet of data transfered is around 8ms. I have try to change the bInterval values(Endpoint Descriptor) to 2(default is 10), the elapsed time for each packet transfered become 2ms. However, I have try to change the bInterval to 1 again, but the elapsed time is larger than 2ms. May i know how to set the elapsed time for each packet transfer become 1ms? IP: Logged |
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Tsuneo Member |
posted August 11, 2010 07:50 PM
What is the Windows version? For XP and later, the HID class driver assigns two transfers queued on the host controller schedule to guarantee 1 ms interval. But before XP, it depends on the type of host controller, and performance of CPU. Tsuneo IP: Logged |
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oscillo New Member |
posted August 11, 2010 10:47 PM
My Windows Version is XP. The HID class driver you mention is a default driver in Windows XP? Do i need to set any configuration on the driver? The two transfers queued are what kind of transfer type, Interrupt or Bulk? Because currently i'm using the USB_HID Mouse sample code(C8051F34x - firmware)to do the testing. I'm not sure there is any setting on USB i need to take care. What i have tried is do a changing on the bInterval value of Endpoint Descriptor. But, i can't get 1 ms interval on each packet transfered. Kindly provide me some advice. Thanks a lot! oscillo IP: Logged |
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Tsuneo Member |
posted August 12, 2010 03:10 AM
As you are working on XP, you should get 1 ms interval without any trick. Try another sniffer. Bus Hound may drop the trace. SniffUsb (free) USBlyzer (one month trial) etc. If you try another sniffer, uninstall current one. Tsuneo IP: Logged |
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oscillo New Member |
posted August 12, 2010 03:55 AM
Hi, Now i'm using USBlyzer to monitor the USB data. May i know how to observe the interval time between each packet transfered? Now, what i can see is the Endpoint Descriptor is shown that the bInterval time is 1ms. oscillo IP: Logged |
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