F-Tile JESD204B Intel® FPGA IP User Guide

ID 723907
Date 4/23/2024
Public
Document Table of Contents

4.2.1.3. Frame Alignment

The frame alignment is monitored through the alignment character /F/. The transmitter inserts this character at the end of frame. The /A/ character indicates the end of multiframe. The character replacement algorithm depends on whether scrambling is enabled or disabled, regardless of the csr_lane_sync_en register setting.

The alignment detection process:

  • If two successive valid alignment characters are detected in the same position other than the assumed end of frame—without receiving a valid or invalid alignment character at the expected position between two alignment characters—the receiver realigns its frame to the new position of the received alignment characters.
  • If lane realignment can result in frame alignment error, the receiver issues an error.

In the F-Tile JESD204B RX IP core, the same flexible buffer is used for frame and lane alignment. Lane realignment gives a correct frame alignment because lane alignment character doubles as a frame alignment character. A frame realignment can cause an incorrect lane alignment or link latency. The course of action is for the RX to request for reinitialization through SYNC_N. 4

4 Dynamic frame realignment and correction is not supported.