We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 42911

13.2 System Generator for DSP - When using the Bitstream Compilation Target Flow, a UCF Must Be Included to LOC Down All I/O


When using the System Generatorbitstream compilation target flow and targeting a Series 7 device such as Virtex-7, Kintex-7, and Artix-7, you might run into a BitGen error if you do not include a constraints file that specifies LOC and IOSTANDARD constraints for all pins. This change in behavior is documented in (Xilinx Answer 41615).


There are severalXFLOW options that you can use when implementing a design in the System Generator tool. These options are discussed in the System GeneratorUser Guide (UG 640), in the "XFLOW Option Files" section. For example, you can use these option files to add or change switches and their values. You can use the default option files as a template for your design environment, including specifying a user constraints file (.ucf) that includes timing, grouping, and pin constraints. It is recommended that you make a copy of the default options file and specify the new customized file that you want to use.

The next procedure outlines this process.

1. Open the SystemGenerator block.

2. Select Compilation as Bitstream.

3. Click the Settings buttonnext to the Compilation field.

4. In the Compilation Target Settings, click XFLOW Options files.

5. Click the open file Icon next to the Implementation Phase field. This opens in the location where the default options files for your installation are located. For a default Windows installation, the location is C:\Xilinx\13.2\ISE_DS\ISE\sysgen\plugins\compliation\Bitstream.

6. The balanced.opt file contains the default implementation options. Make a copy of this file and place it in the same directory to make it easy to find from the settings dialog; for the remainder of this discussion, assume this file is named "K7_balanced.opt".

7. Open "K7_balanced.opt" and find the ngdbuild options towards the top of the file. Before the line "End Program ngdbuild," put the ngdbuild switch that specifies the UCF file:

-uc [path-to-design]\[ucf file]

For Example:

Program ngdbuild

-p [partname]; # Partname to use - picked from xflow commandline

-nt timestamp; # NGO File generation. Regenerate only when

# source netlist is newer than existing

#NGO file (default)

-instyle xflow; # Message Reporting Style: ise, xflow, or silent

#-insert_keep_hierarchy; # Retain hierarchy identified by individual source input netlists

[userdesign]; #User design - pick from xflow command line

[design].ngd; #Name of NGD file. Filebase same as design filebase

-uc c:\my_design\my_ucf.ucf

End Program ngdbuild

8.When specifying XFLOW options files in the Compilation Target Settings dialog, specify the modified file.You must also specify the BitGenoptions file, so select the default "bitgen.opt" file.

Linked Answer Records

Associated Answer Records

AR# 42911
Date Created 07/06/2011
Last Updated 12/15/2012
Status Active
Type General Article
  • System Generator for DSP - 13.2