SerialLite II IP Core User Guide

ID 683179
Date 7/13/2021
Public
Document Table of Contents

2.8.6. Scramble

Scrambling the data eliminates repeating characters, which affect the EMI substantially at high data rates.
A linear feedback shift register (LSFR) is used as a pseudo-random number generator to scramble the data, using the following polynomial equation:
G(x) = X16 + X5 + X4 + X3 + 1

The transmitted bits are XORed with the output of the LFSR in the data stream. At the receiver, the data stream is again XORed with an identical scrambler to recover the original bits. To synchronize the transmitter to the receiver, the COM character initializes the LFSR with the initial seed of 0×FFFF XORed with the lane number (LN).