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AR# 456

Mentor Autologic: inserting PADs instead of PORTs causes XNFPrep ERROR 3527


Keywords: autologic, pad, port, xnfprep, error

Urgency: Standard

General Description:

XNFPrep issues the following on an Autologic design:

The pad `BURN/RUBBER' is connected to the following invalid symbol pins:

Symbol Type = DFF ; Pin Name = D; Symbol Name = BURN/RUBBER

A pad can be connected only to the input pin of input symbols/clock
buffers (such as, the `I` pin of IBUF), and the output pin of output
symbols/PULLUPs/PULLDOWNs (such as, the `Q' pin of OUTFF).


In Mentor, when creating a custom symbol, the schematic underneath must
have PORTs to link the underlying nets to their associated symbol pins.
Mentor's Autologic program takes a designer's HDL and translates it to a
schematic. In its Set Technology Environment dialog, Autologic gives the
user the following three choices:

PADs on top level, PORTs on all others
PADs on all levels
PORTs on all levels

Selecting the option "PADs on all levels" may cause XNFPREP Error 3527, as
this will cause external pads to be created as connections between
hierarchial levels.

In Autologic, under the SETUP menu, there is a Set Tech Environment
selection. A popup will appear that will allow the user to set the
parttype and set a few other options. At the bottom of this popup, there
should be a section named Schematic configuration file that contains the
three above options. Select either "PADs on top level, PORTs on all
others" or "PORTs on all levels".

In some of the earlier verions of the xc2000, xc3000, and xc4000 synthesis
libraries for Autologic, these options were not available. In this case,
you can aquire the newest libraries from Mentor. See Solution 608, "How to
obtain the latest version of the Autologic libraries for Xilinx," for more

The version of the library may be determined by going to the IDEA tree
where the Autologic libraries are located and reading the README file under
the appropriate library directory. The place where the Autologic libraries
are located should be referenced by the MGC_SYNLIB environment variable:

AR# 456
Date Created 08/31/2007
Last Updated 10/01/2008
Status Archive
Type General Article