1 Reply Latest reply on May 10, 2012 4:01 AM by anand.srinivasan.asokan

    endpoints timeout problem in CyUSB .NET




      I'm developing an application in the PC side that receives bytes from FX3 through an "isochronous in endpoint". I need the PC to be waiting for the incoming transfer once the FX3 firmware is running.


      It's supposed that when endpoint "Timeout" is set to a value distinct from 0, the endpoint must wait for that time if the transfer didn't finish before, but it doesn't work. Actually it doesn't wait any time despite the "Timeout" value is really updated (watched with the debugger).


      What I do is:


                  device.IsocInEndPt.TimeOut = 10000; //Wait for 10 seconds


                  bool bResult = isocInEndpoint.XferData(ref bytes, ref xferLen);


      My questions are:


      1. If the PC request data and there isn't any available, the XferData(...) function returns even if the timeout is set to infinite?.


      2. If the PC request data and there isn't enough available, the XferData(...) function returns the available data instead of waiting for all requested data to be available?.


      Thanks in advance,

        • 1. Re: endpoints timeout problem in CyUSB .NET



          Do you by any chance have a CATC analyzer to observe what is happening on the bus?


          For isochronous endpoint since it doesn't have NRDY (or NAK when it comes to USB2.0) the concept of transaction is slightly different than other endpoints. If the host doesn't receive the specified amount of time it'll not have a way of knowing whether it is due to packet corruption of due to lack of response from device. So the host will time out the transaction. Please look at section 8.1 of the USB3.0 spec to understand this better.