Xilinx Answer #528 : PROTEL 2.2: XACT 5.0 Netlister writes out incorrect LOC properties

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PROTEL 2.2: XACT 5.0 Netlister writes out incorrect LOC properties

Record #528
Problem Title:
PROTEL 2.2: XACT 5.0 Netlister writes out incorrect LOC properties

Problem Description:

Solution 1:

PROGRAM: Protel Advanced Schematic

VERSION: 2.2

PLATFORM(s): PC

SHORT DESCRIPTION:

Protel's wirelister doesn't follow the correct netlist format, when translating a pad with an attached "loc=Pxx" attribute, causing LOC attributes to be
ignored.

PROBLEM:

      The Protel Technology Advanced Schematic has a 5.0 xnf wirelister.
However, when a user locks a pad to a specific pin (by attaching a LOC=Pxx
attribute to the pad), the wirelister produces a netlist(XNF file) which
contains an inaccurate format for the EXT record. This incorrect format causes XNFPREP to ignore the LOC attribute and remove them from the EXT record in the
XTF file(Trimmed Netlist File which XNFPREP outputs). Since this is a bug with the Protel wirelister no error, or warning messages will be issued by the XACT
software.

CAUSE:

The error in the netlist format can be seen in two different locations:

      1. In the .xnf file that contains the pad which has the LOC attribute.
      2. In the top_level_design.xff file which is produced by XNFMERGE, and
         provides the input for XNFPREP.

In one of the above files find the EXT record for the signal name that
is being locked down. You will notice that the format is similar to
the format below.

PROTEL GENERAL FORMAT:

      EXT,Signal_Name,Direction(I,O,B),LOC=Pxx

        or with spaces in between different fields.

      EXT, Signal_Name, Direction(I,O,B), LOC=Pxx

This format is different from the format that XNFPREP is expecting because it
is missing a comma. Notice how the correct format has two commas between the
Direction field and the LOC parameter.

XNFPREP EXPECTED FORMAT:

      EXT, Signal_Name, Direction(I,O,B),,LOC=Pxx

        or with spaces between different fields.

      EXT, Signal_Name, Direction, , LOC=Pxx

The EXT record, with the incorrect format, is reproduced in the .xtf file
without any reference to the LOC=Pxx parameter, because XNFPREP has
discarded it. Notice that the LOC Parameter no longer exists, therefore signal will be treated as an unlocked pad.

.XTF EXT RECORD WHEN INCORRECT FORMAT IN .XFF FILE:

      EXT, Signal_NAME, Direction(I,O,B)

SOLUTION:

There are two ways to work around this bug:

      1. Add a comma to the .xnf file following the Direction field comma.
      2. Lock down or constrain the EXT signals in a constraint file.

Since any change in your schematic will necessitate a recompilation of your xnf files, it is recommended that you use method 2. With this method it
isn't necessary to continually change your XNF files, which could
potentially cause other format errors.

End of Record #528 - Last Modified: 03/07/97 08:21

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