IBISWriter is unable to generate models for bidirectional DCI I/Os. The following message is seen when IBISWriter is run:
"No model is available for IOB <pin_name> for configuration value: DIRECTION:BIDIR - Input and/or Output Models may be available."
Distinct input and output IBIS models are required for DCI I/Os, because of the way these models are generated. Since IBISWriter does not find a single model that matches the bidirectional DCI configuration, it gets confused and does not generate any model at all.
To work around this issue: 1 - In your UCF, locate any IOSTANDARD settings that represent I/Os that are both DCI and bidirectional. 2 - Change these IOSTANDARD settings to a different standard, preferably one that is not used elsewhere in the design. 3 - Make a copy of your original design and implement through the Map step. PAR is not necessary. 4 - Run IBISWriter from the command line, using your <my_design>_map.ncd file as the input. 5 - Download the latest version of your target device family's IBIS file from the web: http://www.xilinx.com/xlnx/xil_sw_updates_home.jsp 6 - In the IBIS file you just downloaded, locate the input and output models for your bidirectional DCI I/Os of interest. For example, "SSTL2_II_DCI_I" and "SSTL2_II_DCI_O." 7 - Copy these models into the IBIS file you generated in step (4), replacing the models that were generated for the IOSTANDARD changes you made in step (2). 8 - Modify model names in the IBIS file's [Pin] list to account for the changes in step (7).
A fix to IBISWriter is pending. For more information, please contact Xilinx Technical Support.