AR# 2069: QuickSim II: Output of XBLOX BUS_IFxx component is X
QuickSim II: Output of XBLOX BUS_IFxx component is X
Keywords: fncsim8, xblxgs, xblox, bus_if, unknown
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.
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.