Answers Database

Foundation Simulator: macro outputs always 'Z' during simulation


Record #939

Product Family:  Software

Product Line:  Aldec

Problem Title:
Foundation Simulator: macro outputs always 'Z' during simulation


Problem Description:
Keywords: Foundation, Simulator, Z, output

Urgency: Standard

Problem Description:
During simulation, the outputs of a user-created macro are
always 'Z' (schematic probes are yellow).


Solution 1:

(Note:	The following resolution applies only to version 1.17
of the simulator, shipped with Foundation 6.0.0.)

This can happen if the pin names on the macro symbol are in
lower case.  The simulation netlist will convert all net
names to upper case, but leave the symbol names in lower
case.  The Foundation Logic Simulator is case sensitive, so
connectivity is lost between the symbol pins and the
underlying net names.

While loading the simulation netlist, the following messages
will appear in the Project Manager window:

SIM : Cannot find corresponding block pin for terminal A. Terminal will be
      changed to label
SIM : NODE: A_IN
SIM : No inputs in the node

Select the symbol and choose Options->Symbol Editor.  Change
the pin names to all upper case.



Solution 2:

This can happen if the macro symbol pins are defined as
passive.

Select the symbol and choose Options->Symbol Editor.  The pin
descriptions appear in the lower left section of the editor
window.  If any pin is of type PAS, select the pin.  The pin
name, direction, and shape are listed above the symbol
graphic.  Use the pull-down menus to change the pin type to
IN, OUT, or HIZ (for tristate outputs).



Solution 3:

(The following applies to Foundation F1.x Simulator)

If the macro is generated from VHDL or Abel code, the port
name (pin name) has a length limitation.
1. bus name <= 9 characters long
2. signal name <= 14 characters long
When the VHDL code has port names that exceed this length,
the pin name in the macro will only contain 9 or 14 characters.
(i.e. busnametest: out STD_LOGIC_VECTOR (2 downto 0)
In macro symbol, the pin name changes to busnamete[2:0])
Since the pin name changes in the macro, the connectivity
will be lost between the pin name and the underlying signal.

When loading simulation netlist, you will see the following
message in the Project Manager Window.

SIMUL: Cannot find corresponding block pin for terminal *
Terminal will be changed to label..

Resolution: Limit the length of the pin names in VHDL/Abel code
as specified as above.



End of Record #939