Xilinx UG181 manual Static Timing Analysis, Generating a Bitstream, Xilinx Tool Flow

Models: UG181

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Static Timing Analysis

To evaluate timing closure on a design and create a timing report file (TWR) derived from static timing analysis of the physical design file (NCD), the trce command must be executed. The analysis is typically based on constraints included in the optional physical constraints file (PCF). An example of the trce command is provided below:

trce -e 10 routed.ncd mapped.pcf -o routed.twr

The trce command outputs a routed.twr file, which performs timing analysis of the placed and routed design based on the user constraints.

Timing Simulation

After the user design is functionally correct and meets all timing constraints, it is recommended the user perform back-annotated timing simulation to verify that the entire user design will function correctly before the user tests their design in hardware. The netgen command is used to generate a post-par simulation model, which includes all timing information. An example of the netgen command is provided below:

netgen -sim -ofmt <vhdl verilog> routed.ncd

The netgen command outputs routed.v[hd] and routed.sdf files, which allow the user to run timing simulation.

Generating a Bitstream

To create the configuration (BIT) file based on the contents of a physical implementation file (NCD), the bitgen command must be executed. The BIT file defines the behavior of the programmed FPGA. An example of the bitgen command is provided below:

bitgen -w routed.ncd

Note the user should take care in setting the required bitgen options, including selection of the startup clock. See the Development System Reference Guide for details.

SPI-4.2 Lite v4.3 User Guide

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UG181 June 27, 2008

Page 129
Image 129
Xilinx UG181 manual Static Timing Analysis, Generating a Bitstream, Xilinx Tool Flow