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Chapter 17: IBISWriter
R
to the 50 ohms impedance assumed by XCITE standards. If not specified, the default
impedance value is 50 ohms.
The IBIS standard specifies the format of the output information file, which contains a file
header section and a component description section. The Golden Parser has been developed
by the IBIS Open Forum Group (http://www.eigroup.org/ibis
) to validate the resulting
IBIS model file by verifying that the syntax conforms to the IBIS data format.
The IBISWriter tool requires a design source file as input. For FPGA designs, this is a
physical description of the design in the form of an NCD (native circuit description) file
with a .ncd file extension. For CPLD designs, the input is produced by CPLDfit and has a
.pnx file extension.
IBISWriter outputs a .ibs file. This file comprises a list of pins used by your design; the
signals internal to the device that connect to those pins; and the IBIS buffer models for the
IOBs connected to the pins.
Note:
Virtex-II Pro architecture does not include the multi-gigabit transceiver (MGT). There are no
IBIS models available for these IOBs.
To see an example of an IBIS file, refer to Virtex Tech Topic VTT004 at the following web
location: http://www.xilinx.com/products/virtex/techtopic/vtt004.pdf
The following figure shows the IBISWriter flow:
IBISWriter Syntax
Use the following syntax to run IBISWriter from the command line:
ibiswriter
[options] infile outfile[.ibs]
options is one or more of the options listed in “IBISWriter Options”.
infile is the design source file for the specified design. For FPGA designs, infile must have a
.ncd extension. For CPLD designs, infile is produced by the CPLDfit and must have a .pnx
extension.
outfile[.ibs] is the destination for the design specific IBIS file. The .ibs extension is optional.
The length of the IBIS file name, including the .ibs extension, cannot exceed 24 characters.
Figure 17-1: IBISWriter Flow
X9553
IBISWriter
IBS
NCD PNX