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XferData sends data twice | Cypress Semiconductor

XferData sends data twice

Summary: 1 Reply, Latest post by aasi on 21 Aug 2013 06:52 PM PDT
Verified Answers: 0
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MrSzymonello's picture
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I have a USB device and I'd like to be able to communicate with it. Device uses cyusb.sys driver installed with Cypress Suite USB 3.4.7. Before starting work on my own application I used CyConsole and Control Center both available with 3.4.7 Suite. I tried to send 2 byte data to device. In order to see data transmitted through USB cable I used USBlyzer software. I noticed that data is sent twice to device (see attached picture). CyConsole and Control Center uses XferData method to send data. I have 64 bit Windows 7.

I searched forum to see if anyone had such problem but I didn't find anything. Does anyone knows how to solve this problem?

aasi's picture
Cypress Employee
1166 posts

 usblyzer is a software level capture tool. It gives you information on what goes on between our driver and the usb bus driver. It is not an depiction of the actual traffic on bus. Also I've seen the output change from version to version as well as from PC to PC so I'm not entirely sure what is leading to this.
our stack has been completely tested and I'm pretty sure this is not really an issue but the way usblyzer depicts a single transfer. For eg: look at this screenshot from their site

bulk or interrupt transfers are being depicted twice (the two 3900 case as well as the 0 case).

The easier way of checking if the stack is working alright would be to use the bulkloop firmware and check and make sure the data is not being sent twice by receiving the data back and checking that only one packet was sent.


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