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We are using the basic FTDI dll plus an own dll which implements our interface...
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Thanks for the description.
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This worked very well, but there was a bug occuring very rarely, sometimes after a few minutes, sometimes after several hours. The cause of the bug was what I described above.
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The lesson to take away from that experience is that you need to write a testbench that includes a bus functional model (BFM) of the FTDI FT2232H synchronous interface. Your testbench should then generate activity over the synchronous interface that matches the data streams you send from the PC. This is where using Wireshark and SignalTap II to trace the activity is important, as you can see from those traces whether the USB data is sent in a single USB packet, or whether it is spread over several USB packets. Reimplement those hardware measurement sequences in your BFM and then randomize the order in which you generate command sequences them to your design. That will improve your confidence that the design will operate under all conditions.
If you have Modelsim-SE, then you can use advanced features like code coverage. However, the above sequence works well in Modelsim-ASE.
Cheers,
Dave
Honored Contributor
