Xilinx 8.2i manual 4Logical Circuit Representation

Models: 8.2i

1 422
Download 422 pages 26.35 Kb
Page 146
Image 146

Chapter 7: MAP

R

This command creates a back-annotated simulation netlist using the logical-to-physical cross-reference file named mapped.ngm. This cross-reference file contains information about the logical design netlist, and the back-annotated simulation netlist (mapped.nga) is actually a back-annotated version of the logical design. However, if MAP makes a physical error, for example, implements an Active Low function for an Active High function, this error will not be detected in the mapped.nga file and will not appear in the simulation netlist.

For example, consider the following logical circuit generated by NGDBuild from a design file, shown in the following figure.

A * B + C * D

A

B

D Q

C

D

CLK

X8549

Figure 7-4:Logical Circuit Representation

Observe the Boolean output from the combinatorial logic. Suppose that after running MAP for the preceding circuit, you obtain the following result.

CLB

A

B

LUT

C

D

A * B + C * D

D Q

CLK

X8550

Figure 7-5:CLB Configuration

Observe that MAP has generated an active low (C) instead of an active high (C). Consequently, the Boolean output for the combinatorial logic is incorrect. When you run NetGen using the mapped.ngm file, you cannot detect the logical error because the delays are back-annotated to the correct logical design, and not to the physical design.

146

www.xilinx.com

Development System Reference Guide

Page 146
Image 146
Xilinx 8.2i manual 4Logical Circuit Representation

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.