pci總線是目前最為流行的一種局部性總線 通過對pci總線一些典型功能的分析以及時序的闡述，利用VetilogHDL設計了一個將非pci功能設備轉接到PC1總線上的IP Core 同時，通過在ModeISim SE PLUS 6．0
上運行測試程序模塊，得到了理想的仿真數據波形，從軟件上證明了功能的實現。
The pci Special Interest Group disclaims all warranties and liability for the use of this document and the information contained herein and assumes no responsibility for any errors that may appear in this document, nor does the pci Special Interest Group make a commitment to update the information contained herein.
The Virtex-4 features, such as the programmable IDELAY and built-in FIFO support, simplifythe bridging of a high-speed, pci-X core to large amounts of DDR-SDRAM memory. Onechallenge is meeting the pci-X target initial latency specification. pci-X Protocol Addendum tothe pci Local Bus Specification Revision 2.0a ([Ref 6]) dictates that when a target signals adata transfer, "the target must do so within 16 clocks of the assertion of FRAME#." pcitermination transactions, such as Split Response/Complete, are commonly used to meet thelatency specifications. This method adds complexity to the design, as well as additional systemlatency. Another solution is to increase the ratio of the memory frequency to the pci-X busfrequency. However, this solution increases the required power and clock resource usage.
This document provides practical, common guidelines for incorporating pci Express interconnect
layouts onto Printed Circuit Boards (PCB) ranging from 4-layer desktop baseboard designs to 10-
layer or more server baseboard designs. Guidelines and constraints in this document are intended
for use on both baseboard and add-in card PCB designs. This includes interconnects between pci
Express devices located on the same baseboard (chip-to-chip routing) and interconnects between
a pci Express device located “down” on the baseboard and a device located “up” on an add-in
card attached through a connector.
This document is intended to cover all major components of the physical interconnect including
design guidelines for the PCB traces, vias and AC coupling capacitors, as well as add-in card
edge-finger and connector considerations. The intent of the guidelines and examples is to help
ensure that good high-speed signal design practices are used and that the timing/jitter and
loss/attenuation budgets can also be met from end-to-end across the pci Express interconnect.
However, while general physical guidelines and suggestions are given, they may not necessarily
guarantee adequate performance of the interconnect for all layouts and implementations.
Therefore, designers should consider modeling and simulation of the interconnect in order to
ensure compliance to all applicable specifications.
The document is composed of two main sections. The first section provides an overview of
general topology and interconnect guidelines. The second section concentrates on physical layout
constraints where bulleted items at the beginning of a topic highlight important constraints, while
the narrative that follows offers additional insight.
