Answers Database

M1.3: Map removes IBUF along with unused OBUFT in a bidirectional I/O


Record #2884

Product Family:  Software

Product Line:  Merged Core

Problem Title:
M1.3: Map removes IBUF along with unused OBUFT in a bidirectional I/O


Problem Description:
Keywords: remove, bidirectional, unused

Urgency: standard

General description:
Map removes an IBUF along with the unused OBUFT in a
bidirectional I/O pin.



Solution 1:

This problem was observed when the OBUFT was embedded under an
user-generated XNF output macro in which the pin corresponding
to the output of the OBUFT had been assigned a direction of
"O" when it was instantiated in the design.  NGDBUILD is
unable to determine that the underlying output pin is
bidirectional, and ends up trimming the IBUF along with the
unused OBUFT.

Example.  Given the following output macro instantiation with
the pin direction of the "O" pin specified as "O"  (PIN, O, O,
PAD_A):

SYM, Output_A, OBUFTPUF, LIBVER=2.0.0
PIN, O, O, PAD_A
PIN, I, I, GND
PIN, T, I, VCC
END

Change the "O" to a "B" to give:

PIN, O, B, PAD_A


Modified instantiation:

SYM, Output_A, OBUFTPUF, LIBVER=2.0.0
PIN, O, B, PAD_A
PIN, I, I, GND
PIN, T, I, VCC
END


This problem will be fixed in the M1.4 release through a
modification of the XNF2NGD program.  However, it cannot
be fixed in the M1.3 release, and customers must use
this workaround.

Reference # 101103



Solution 2:





End of Record #2884