Answers Database

QuickSim II: Output of XBLOX BUS_IFxx component is X


Record #2069

Product Family:  Software

Product Line:  Mentor

Problem Title:
QuickSim II: Output of XBLOX BUS_IFxx component is X


Problem Description:
Keywords: fncsim8, xblxgs, xblox, bus_if, unknown

Urgency: Standard

General description:

In a functional simulation in QuicksimII of a design that contains XBLOX
components, the outputs of BUS_IF (bus interface) symbols, such as
BUS_IF16, are X (unknown) even thoough the input is a valid logic value.


Solution 1:

This is caused when the bounded side of the BUS_IFxx component is driven by
an XBLOX INPUTS symbol with a BOUNDS=0:0 attribute applied to it.

To fix this remove the BOUNDS and ENCODING attributes from the INPUTS
instance.  If the INPUTS symbol is connected to a single NET, then
XBLXGS/XBLOX will infer a single bit width, and thus the BOUNDS attribute is
not necessary.



End of Record #2069