R

XFLOW Flow Types

–mppr (Multi-Pass Place and Route for FPGAs)

–mpproption_file

This flow type runs multiple place and route passes on your FPGA design. It invokes the fpga.flw flow file and runs NGDBuild, MAP, multiple PAR passes, and TRACE. After running the multiple PAR passes, XFLOW saves the “best” NCD file in the subdirectory called mppr.dir. (Do not change the name of this default directory.) This NCD file uses the naming convention placer_level_router_level_cost_table.ncd.

XFLOW then copies this “best” result to the working directory and renames it

design_name.ncd. It also copies the relevant DLY, PAD, PAR, and XPI files to the working directory.

Note: By default, XFLOW does not support the multiple-node feature of the PAR Turns Engine. If you want to take advantage of this UNIX-specific feature, you can modify the appropriate option file to include the PAR –m option. See “–m(Multi-Tasking Mode)” in Chapter 9 for more information.

Xilinx provides the following option files for use with this flow type. These files allow you to set how exhaustively PAR attempts to place and route your design.

Note: Each place and route iteration uses a different “cost table” to create a different NCD file. There are 100 cost tables numbered 1 through 100. Each cost table assigns weighted values to relevant factors such as constraints, length of connection, and available routing resources.

Table 23-10:Option Files for –mppr Flow Type

Option Files

Description

 

 

overnight.opt

Runs 10 place and route iterations

 

 

weekend.opt

Runs place and route iterations until

 

the design is fully routed or until 100

 

iterations are complete

 

 

exhaustive.opt

Runs 100 place and route iterations

 

 

The following example shows how to use the -mppr flow type:

xflow –p xc2v250fg256-5 –mppr overnight.opt testclk.edf

–sta (Create a File for Static Timing Analysis)

–staoption_file

This flow type generates a file that can be used to perform static timing analysis of an FPGA design. It invokes the fpga.flw flow file and runs NGDBuild and NetGen to generate a Verilog netlist compatible with supported static timing analysis tools.

Xilinx provides the following option file for use with this flow type.

Table 23-11:Option Files for –sta Flow Type

Option File

Description

 

 

primetime_verilog.opt

Option file for static timing analysis of

 

Primetime.

 

 

Development System Reference Guide

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Xilinx 8.2i manual Mppr Multi-Pass Place and Route for FPGAs, Sta Create a File for Static Timing Analysis
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8.2i specifications

Xilinx 8.2i is a significant version of the Xilinx ISE (Integrated Software Environment) that emerged in the early 2000s, marking an important milestone in the world of FPGA (Field-Programmable Gate Array) development. This version introduced a slew of advanced features, technologies, and characteristics that made it an indispensable tool for engineers and developers in designing, simulating, and implementing digital circuits.

One of the standout features of Xilinx 8.2i is its enhanced design entry capabilities. This version supports multiple design entry methods, including schematic entry, VHDL, and Verilog HDL, giving engineers the flexibility to choose their preferred approach. The integrated environment provides user-friendly graphical interfaces, making it accessible for both novice and experienced users.

Xilinx 8.2i's synthesis tools have been improved to enable more efficient design compilation and optimization. The new algorithms used in this version facilitate faster synthesis times while reducing power consumption and improving performance. Furthermore, it features support for advanced FPGA architectures, which allows for the implementation of more complex designs with greater efficiency.

The implementation tools in Xilinx 8.2i include advanced place and route capabilities, utilizing state-of-the-art algorithms for optimized resource usage. These tools enable designers to make better use of FPGA resources, ensuring that designs fit within the constraints of the target device while maximizing performance.

Another key characteristic of Xilinx 8.2i is its extensive support for various Xilinx devices such as the Spartan, Virtex, and CoolRunner series. This compatibility ensures that developers can leverage the powerful features of these FPGA families, including high-speed transceivers and DSP slices.

Xilinx 8.2i also places a strong emphasis on simulation and verification. The version integrates with various simulation tools, allowing for thorough testing of the designs before implementation. This reduces the risk of errors and ensures that the final product meets specifications.

In addition, this version includes support for design constraints, enabling engineers to specify timing, area, and other critical design parameters. By accommodating constraints, Xilinx 8.2i helps in achieving reliable and efficient designs tailored to project needs.

In summary, Xilinx 8.2i is a robust software development tool that enhances the design process for FPGAs. Its comprehensive features, including multiple design entry options, advanced synthesis and implementation tools, extensive device support, and strong simulation capabilities, make it a valuable resource for engineers and developers striving for innovation in digital design.
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