E-Tile Transceiver PHY User Guide

ID 683723
Date 9/30/2022
Public
Document Table of Contents

3.1.9.1. Transceiver Interface Deskew Logic

When you enable bonding in the Native PHY IP core for PMA Direct and high data rate PMA Direct modes only, the deskew logic in the transceiver interface aligns data transferred across multiple channels within the same clock cycle where E-tile uses the deskew bits to deskew all EMIB channels in the bonded configuration. However, the same mechanism applies even when bonding is not enabled in high data rate mode only.

For k = 0, … N-1 with N channels + single width + separate interface per channel disabled, _data[33+k*80] are the deskew bits.

For k = 0, … N-1 with N channels + single width + separate interface per channel enabled, _data_ch<k>[33] are the deskew bits.

For k = 0, … N-1 with N channels + double width + separate interface per channel disabled, _data[33+k*80] and _data[73+k*80] are the deskew bits.

For k = 0, … N-1 with N channels + double width + separate interface per channel enabled, _data_ch<k>[33] and _data_ch<k>[73] are the deskew bits.

You must perform Avalon® memory-mapped interface read to the TX deskew status register, cfg_tx_deskew_sts, of all the bonded lanes to determine whether or not deskew is completed successfully. If it has, all the bonded channels have aligned parallel data. The deskew status register also provides further information for debugging if deskew is not successful.

cfg_tx_deskew_sts[2] - (0x09[4]):

  • 0 = not aligned or not enabled or did't receive a deskew-bit
  • 1 = aligned

cfg_tx_deskew_sts[1:0] - (0x09[3:2]):

  • 00 = not yet received a deskew-bit
  • 01 = not aligned
  • 10 = received 1 set of aligned deskew-bits
  • 11 = received 16 sets of aligned deskew-bits

The deskew mechanism runs continuously, so if the alignment lock is lost for some reason, monitoring cfg_tx_deskew_sts informs you about the status. The deskew mechanism works the same way for PMA Direct high data rate PAM4 mode for two EMIB channels. You must send the deskew pulses for the data you sent to two EMIBs and at the master transceiver interface they are aligned to before being sent to a single PMA.

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