V-Series Transceiver PHY IP Core User Guide

ID 683171
Date 7/26/2022
Public
Document Table of Contents

10.3.2. Word Alignment Parameters

The word aligner restores word boundaries of received data based on a predefined alignment pattern. This pattern can be 7, 8, 10, 16, 20, or 32 bits long. The word alignment module searches for a programmed pattern to identify the correct boundary for the incoming stream.
Table 126.  Word Aligner Options
Name Value Description
Word alignment mode Manual In this mode you enable the word alignment function by asserting rx_enapatternalign using the Avalon-MM interface. When the PCS exits reset, the word aligner automatically performs an initial alignment to the specified word alignment pattern when the interface between the PCS and PMA is 16 or 20 bits. For other cases, you must assert rx_enapatternalign to initiate another pattern alignment. rx_enapatternalign is edge sensitive in most cases; however, if the PMA‑PCS interface width is 10 bits, it is level sensitive.
Bit slipping You can use bit slip mode to shift the word boundary using the Avalon-MM interface. For every rising edge of the rx_bitslip signal, the word boundary is shifted by 1 bit. Each bit slip removes the earliest received bit from the received data.
Word alignment mode Automatic synchronization state machine In this mode, word alignment is controlled by a programmable state machine. This mode can only be used with 8B/10B encoding. The data width at the word aligner can be 10 or 20 bits. You can specify the following parameters:
  • Number of consecutive valid words before sync state is reached: Specifies the number of consecutive valid words needed to reduce the built up error count by 1. Valid values are 1-256.
  • Number of bad data words before loss of sync state: Specifies the number of bad data words required for alignment state machine to enter loss of sync state. Valid values are 1-256.
  • Number of valid patterns before sync state is reached: Specifies the number of consecutive patterns required to achieve synchronization. Valid values are 1-256.
Create optional word aligner status ports: When enabled the rx_syncstatus and rx_patterndetect status ports are created.
  • Word alignment pattern length: Allows you to specify a 7-, 10‑, or 20‑bit pattern for use in the word alignment state machine. The 20‑bit pattern is available when the PMA‑PCS interface width is 20 bits.
  • Word alignment pattern: Allows you to specify a word alignment pattern.
Enable run length violation checking On/Off If you turn this option on, you can specify the run length which is the maximum legal number of contiguous 0s or 1s.
Run length 40-640 Specifies the threshold for a run-length violation.
Table 127.  More Information about Word Aligner Functions
PMA-PCS Interface Width (bits) Word Alignment Mode Word Alignment Pattern Length (bits) Word Alignment Behavior
8 Manual alignment 8, 16 User-controlled signal starts alignment process. Alignment occurs once unless signal is re-asserted.
10 Manual alignment 7 , 10 User-controlled signal starts alignment process. Alignment occurs once unless signal is re-asserted.
Automatic synchronized state machine Data must be 8B/10B encoded and aligns to selected word aligner pattern.
16 Manual alignment 8 , 16, 32 User-controlled signal starts alignment process. Alignment occurs once unless signal is re-asserted.
20 Manual alignment 7, 10, 20, 40 User-controlled signal starts alignment process. Alignment occurs once unless signal is re-asserted.
Automatic Synchronized State Machine 7, 10, 20 Automatically selected word aligner pattern length and pattern.