Intel® Cyclone® 10 GX Transceiver PHY User Guide

ID 683054
Date 4/14/2023
Document Table of Contents

2.5.1. Metaframe Format and Framing Layer Control Word

The Enhanced PCS supports programmable metaframe lengths from 5 to 8192 words. However, for stability and performance, Intel recommends you set the frame length to no less than 128 words. In simulation, use a smaller metaframe length to reduce simulation times. The payload of a metaframe could be pure data payload and a Burst/Idle control word from the MAC layer.

Figure 17. Framing Layer Metaframe Format

The framing control words include:

  • Synchronization (SYNC)—for frame delineation and lane alignment (deskew)
  • Scrambler State (SCRM)—to synchronize the scrambler
  • Skip (SKIP)—for clock compensation in a repeater
  • Diagnostic (DIAG)—provides per-lane error check and optional status message

To form a metaframe, the Enhanced PCS frame generator inserts the framing control words and encapsulates the control and data words read from the TX FIFO as the metaframe payload.

Figure 18. Interlaken Synchronization and Scrambler State Words Format
Figure 19. Interlaken Skip Word Format

The DIAG word is comprised of a status field and a CRC-32 field. The 2-bit status is defined by the Interlaken specification as:

  • Bit 1 (Bit 33): Lane health
    • 1: Lane is healthy
    • 0: Lane is not healthy
  • Bit 0 (Bit 32): Link health
    • 1: Link is healthy
    • 0: Link is not healthy

The tx_enh_frame_diag_status[1:0] input from the FPGA fabric is inserted into the Status field each time a DIAG word is created by the framing generator.

Figure 20. Interlaken Diagnostic Word