ADM-XRC SDK 2.8.1 User Guide (Linux)
© Copyright 2001-2009 Alpha Data


FPGA Express issues

There are two several issues that affect users of FPGA Express when building the example designs in the SDK:

  1. Hierarchical separator character

    XST uses the _ (underscore) character as a hierarchy separator, whereas FPGA Express uses a / (forward slash) character. It is possible to work around this problem, as far as constraints in .UCF files go, by using the ? wildcard (match any single character) in the .UCF file.

  2. Hierarchical net naming in netlist

    XST names nets that are not at the top level differently to FPGA Express. A full description of the XST naming convention can be found in the XST user guide. FPGA Express names a net strictly according to its name and the highest hierarchy level in which that net is found. Fortunately, it is often possible to avoid needing to reference nets that are not in the top level in a .UCF file.

  3. Hierarchical primitive instance naming in netlist

    XST names certain types of primitive, for example clock buffers, according to their hierarchy level, their label and their type. FPGA Express names an instance strictly according to its label and hierarchy level.

 


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