Xilinx CPLD Libraries Guide

About this Guide
This guide is part of the ISE documentation collection and covers the use of Xilinx design elements in schematics.
A separate version of this guide is also available if you prefer to work with Verilog or VHDL in your circuit
design activities.
This guide contains the following:
• A general introduction to the design elements, including descriptions of the types of elements available in
this architecture.
• A list of pre-existing design elements are automatically changed by the ISE software tools when they are
used in this architecture, thus ensuring that you are always able to take full advantage of the latest circuit
design advances.
• A list of the design elements that are supported in this architecture, organized by functional categories. Click
on the element of your choice to immediately access its profile.
• Individual profiles describing each of the primitives and macros, and including, as appropriate, for each
element:
• Its formal name
• A brief introduction to each element, including the names of all architectures in which it is supported
• Its schematic symbol
• Logic tables (if any)
• Port descriptions (if any)
• A list of available attributes
• VHDL and Verilog instantiation code
• References to any additional sources of information
About this Architecture
This version of the Libraries Guide describes the categories of design elements that comprise the Xilinx Unified
Libraries for this architecture. These categories are:
• Primitives - The simplest design elements in the Xilinx libraries. Primitives are the design element "atoms."
Primitives can be created from primitives or macros. Examples of Xilinx primitives are the simple buffer,
BUF, and the D flip-flop with clock enable and clear, FDCE.
• Macros - The design element "molecules" of the Xilinx libraries. Macros can be created from the design
element primitives or macros. For example, the FD4CE flip-flop macro is a composite of 4 FDCE primitives.
Xilinx maintains software libraries with hundreds of functional design elements (unimacros and primitives) for
different device architectures. New functional elements are assembled with each release of development system
software. In addition to a comprehensive Unified Library containing all design elements, this guide is one in a
series of architecture-specific libraries.
CPLD Libraries Guide
ISE 10.1 www.xilinx.com 1