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198 www.xilinx.com Development System Reference Guide
Chapter 10: XPower
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Files Used by XPower
XPower uses the following file types:
• CXT - File produced by CPLDfit and used by XPower to calculate and display power
consumption.
• NCD - An physical design file produced by MAP and PAR that contains information
on an FPGA. Xilinx recommends using a fully placed and routed NCD design
(produced by PAR) to get the most accurate power estimate. Using a mapped-only
NCD (produced by MAP) file may compromise accuracy.
• PCF - An optional user-modifiable ASCII Physical Constraints File (PCF) produced by
MAP. The PCF contains timing constraints that XPower uses to identify clock nets (by
using the period constraint) and GSRs (by looking at TIGs). Temperature and voltage
information is also available if these constraints have been set in the User Constraints
FIle (UCF).
Note:
The Innoveda CAE tools create a file with a .pcf extension when generating a plot of an
Innoveda schematic. This PCF is not related to a Xilinx PCF. Because XPower automatically
reads a PCF with the same root name as your design file, make sure your directory does not
contain an Innoveda PCF with the same root name as your NCD file.
• VCD - Output file from simulators. XPower uses this file to set frequencies and
activity rates of internal signals, which are signals that are not inputs or outputs but
internal to the design. For a list of supported simulators, see the “VCD Data Entry”
section of this chapter.
• XAD - Output file that provides most of the information contained in the VCD file,
but is much smaller in size to reduce runtime.
• XML - Settings file from XPower. Settings for a design can be saved to an XML file
and then reloaded into XPower for the same design. Data input such as frequencies,
toggle rates, and capacitance loads can be saved to this file to avoid entering the same
information the next time the design is loaded into XPower.
XPower Syntax
Use the following syntax to run XPower from the command line:
FPGA Designs
xpwr infile[.ncd] [constraints_file[.pcf]] [options] -o design_name.pwr
CPLD Designs
xpwr infile[.cxt] [options] -o design_name.pwr
infile is the name of the input physical design file. If you enter a filename with no extension,
XPower looks for an NCD file with the specified name. If no NCD file is found, XPower
looks for a CXT file.
constraints file is the name of the Physical Constraints File (PCF). This optional file is used
to define timing constraints for the design. If you do not specify a PCF, XPower looks for
one with the same root name as the input NCD file. If a CXT file is found, XPower does not
look for a PCF file.