Xilinx Virtex-5 RocketIO GTP - Chapter 8: Cyclic Redundancy Check (CRC); CRC Block Overview

Virtex-5 RocketIO GTP Transceiver User Guide www.xilinx.com 187
UG196 (v1.3) May 25, 2007
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Chapter 8
Cyclic Redundancy Check (CRC)
Overview
In Virtex-5 devices, each high-speed transceiver tile is paired with two CRC integrated
blocks. Each CRC block can operate independently as two 32-bit input CRC modules
(CRC32) or can be combined into a single 64-bit input CRC module (CRC64). The CRC
modules use the standard 32-bit Ethernet polynomial for CRC calculation. The CRC
integrated blocks are independent of the transceiver blocks.
Figure 8-1 shows the basic port interface of the CRC block.
For clarification:
• Each GTP_DUAL tile is paired with two integrated CRC blocks.
• Each integrated CRC block can either operate as one 64-bit wide CRC module or as
two independent 32-bit wide CRC modules.
• For a given GTP_DUAL, four independent 32-bit wide CRC modules are only
possible when a 64-bit wide CRC module is not used.
Figure 8-2 shows how CRC modules are typically used in an application.
Figure 8-1: CRC Integrated Block
CRC Block
CRCOUT[31:0]
UG196_c8_01_100506
CRCIN[63/31:0]
CRCDATAVALID
CRCRESET
CRCCLK
CRCDATAWIDTH[2:0]