Answers Database M1.3 MAP: On a bidirectional I/O, the INFF and pad are also trimmed even though only the OUTFF is dangling Record #2753 Product Family: Software Product Line: FPGA Implementation Product Part: ngdbuild Product Version: 1.3. Problem Title: M1.3 MAP: On a bidirectional I/O, the INFF and pad are also trimmed even though only the OUTFF is dangling Problem Description: Urgency: standard General Description: If a pad has both an INFF and an OUTFF, where the INFF is used, but the OUTFF is not, MAP correctly deletes the unused OUTFF, but then goes on to incorrectly delete the INFF and the pad itself. The problem is seen when the input is an XNF file referencing OFDT's for tristatable output flip-flops. The correct symbol to reference is the XNF-standard OUTFFT. The result of referencing the OFDT is that the output pin type of the OFDT symbol is incorrectly marked as "output" instead of "tristate" by XNF2NGD. When combined with an input symbol, this results in an output of type PAD in the NGD database, instead of an output of type BIDIRECT. This then causes map to trim the entire IO structure when only the output side is unused. Solution 1: A patch to XNF2NGD has been bundled into the M1.3.7 Map patch as of September 17, 1997. In the meantime, the workaround is to substitute any OFDT symbol references in your XNF file with "OUTFFT". Reference No.: 100274, 18522 End of Record #2753 - Last Modified: 10/12/97 23:51

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