To perform a timing simulation with Workview Office, a file called TIME_SIM.EDN can be created from the M1 Design Manager. This EDIF file must be read back into the Viewlogic environment using a program called EDIFNETI. The following warnings may appear while reading the TIME_SIM.EDN file:
<<<WARNING>>> - Unconnected port I2 in cell XBA1 <<<WARNING>>> - Unconnected port I3 in cell XBA1 <<<WARNING>>> - Unconnected port I0 in cell XBA2 <<<WARNING>>> - Unconnected port COUT in cell XBA3 <<<WARNING>>> - Unconnected port D0 in cell XBA3 <<<WARNING>>> - Unconnected port F1 in cell XBA3 ...
These XBA## files are levels of hierarchy that describe the design on the logic level. The XBA## names are used to prevent overwriting the original WIR files when the timing simulation netlist is read in. They are required to perform a hierarchical gate-level simulation.
This behaviour is only seen with Workview Office 7.3 and newer with M1.2 only.
Solution
1
One way to avoid these warnings is to create a flattened EDIF file to be used for the timing simulation. Run the following command in DOS from your project directory:
ngd2edif -n -v viewlog <design>.ngd time_sim.edn
where <design> is the name of your top-level design, and time_sim.edn can be changed to allow both flattened and hierarchical EDIF files to co-exist. The -n option produces the flattened netlist.
The drawback of this solution is that you will not have complete back-annotation to your schematic. Nets that descend into the hierarchy will have unknown values on the lower levels. Again, this will not affect the overall simulation results, but can impair your ability to debug the simulation.
2
The "Unconnected port" warnings are valid but harmless. The XBA files describe the logic at different levels, from the function generators to CLB logic to the logic block itself. These files are generically built with all the possible pins, then the logic from the placed and routed design is added. Because each component does not use all the possible resources, some pins will be left unconnected.
For example: Let's say that XBA1 described an F function generator containing a three-input AND gate. This function generator has four inputs and one output, so pins I0, I1, I2, and O will be used. However, pin I3 will be left unused, so EDIFNETO will produce the warning for XBA1.
The warnings can be safely ignored because they have no effect on the simulation. This issue has been fixed with M1.3.
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AR# 2536
Date
03/27/2000
Status
Archive
Type
General Article
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