Answers Database

Foundation F1.3/F1.4, Timing Simulation: When bus has same label, but different indices, get X out


Record #3222

Product Family:  Software

Product Line:  Aldec

Problem Title:
Foundation F1.3/F1.4, Timing Simulation: When bus has same label, but
different indices, get X out



Problem Description:
Keywords: Foundation, Timing Simulation, F1.3, bus, X

Urgency:  Standard

General Description:

Using F1.x for Timing Simulation, when a label is used for an input bus with one
 set of indeces (eg 15:8) and an output bus with another set of indices (eg 7:0)
, the timing simulator does
not distinguish between the two busses. The result is 'X' (undefined) outputs fo
r the input bus. The only signal that can
be selected for simulation is a bus of 15:0 as an output.


Solution 1:

The workaround is to name the busses differently.

Example:
Originally,
Input bus =  HOBSON[15:8]
Output bus = HOBSON[7:0]
These are 2 independent busses, but the timing simulator does not recognize that
.

Solution
Input bus = HOBSON[15:8]
Output bus = BERNIE[7:0]
This clearly defines 2 independent busses and is handled fine by the simulator.
(The names are user defined and can be anything, just so they are different)



End of Record #3222