Answers Database

M1 NGDBUILD: ERRORS: basnu - logical net...has multiple drivers, illegalconnection, no legal driver, no driver...


Record #2870

Product Family:  Software

Product Line:  FPGA Implementation

Problem Title:
M1 NGDBUILD: ERRORS: basnu - logical net...has multiple drivers,
illegalconnection, no legal driver, no driver...



Problem Description:
Keywords: NGDBUILD, basnu, DRC, multiple drivers, illegal connections, no legal
driver, Foundation, M1

Urgency: Standard

General Description:
When Translating a design from a Foundation Project in M1.3.7,
Logical Design DRC gives messages about multiple drivers
and illegal connections:

 ERROR:basnu - logical net "$Net00014_" has multiple drivers
 ERROR:basnu - input pad net "$Net00014_" has illegal connection

 WARNING:basnu - logical net "$Net00051_" has no driver
 WARNING:basnu - output pad net $Net00051_" is not driven by an
 ouput symbol
 WARNING:basnu - output pad net '$Net00052_" has no legal driver


Solution 1:

A macro sheet may be incorrectly included as a top-level sheet in the Foundation
 Project Manager.

In the Foundation Project Manager, the top-level schematics
will be listed with .sch extensions in the Hierarchy Browser.
Verify that each schematic listed there is a top-level sheet.
If there are any macros or other sheets that are not intended
to be top-level, select each sheet (one at a time) and go to
Document -> Remove, to remove them.

This does not delete the schematic--it only removes it from
the top-level project view.  Now re-run M1 Design Manager by
clicking on the M1 icon within the Foundation Project Manager.

The above scenario presents a problem because a macro net may
be given the same net name (by the software) as a top-level
net, but since it is hierarchical, the full name includes the
hierarchy. If a macro is referred to as a top-level,
then the hierarchical path part of the name is lost, and the
nets end up with the same names, causing the multiple driver
errors.




Solution 2:

Multiple Project (.pdf) files and/or multiple top-level EDIF
(.edn) files may exist within the project directories.

Exit Foundation and open up Windows Explorer 95/NT.

Verify that the Project file 'project_name.pdf' is in the
project's root directory (e.g. c:\active\projects).

Then check in the project's sub-directory
(e.g. c:\active\projects\project_name)
for another 'project_name.pdf' file. If found, delete this second .pdf file.

Also, delete the top-level EDIF file (project_name.edn) from
this sub-directory, if found.  If there is a copy of the top-level EDIF file in
the root directory, delete it as well.

Now, delete the xproj directory (c:\active\projects\project_name\xproj)
to allow M1 to update. Re-start Foundation, then re-invoke M1 Design Manager



Solution 3:

Another cause of this problem has been seen with the flow
merging XNF files from the Xilinx CORE Generator into a
Foundation F1.4 schematic.

COREGen uses the Foundation program NET2SYM to generate a
Foundation symbol for an IP core function.  In F1.4, this program appears to als
o merge the XNF file for the Core into
the Foundation .ALR file.  Subsequently at the "Export
Netlist" step, it writes out an invalid EDIF file which
generates the "multiple driver" error in NGDBUILD.

The workaround is to regenerate the .ALR and symbol for
the Coregen block.  To do this, you must copy the .XSF and
.XNF files generated by COREGen to a new project directory,
then run "Create Macro Symbol from Netlist" on the Core XNF
file.  In F1.4, running this step should not merge the XNF
into the .ALR.	The generated symbol should have the required
"$EXPORT=NO" property attached to it to prevent the associated
XNF file from being merged into the output EDIF file when you
run "Export Netlist".



End of Record #2870