Answers Database

M1.3 MAP: On a bidirectional I/O, the INFF and pad are also trimmed eventhough only the OUTFF is dangling


Record #2753

Product Family:  Software

Product Line:  Merged Core

Problem Title:
M1.3 MAP: On a bidirectional I/O, the INFF and pad are also trimmed
eventhough only the OUTFF is dangling



Problem Description:
Keywords: map, inff, outff, trim, dangling, ngdbuild

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