JESD204B Intel® FPGA IP User Guide

ID 683442
Date 8/18/2022
Public
Document Table of Contents

4.1.1.3. User Data Phase

During the user data phase, character replacement at the end of frame and end of multiframe is opportunistically inserted so that there is no additional overhead for data bandwidth.

Character replacement for non-scrambled data

The character replacement for non-scrambled mode in the IP core follows these JESD204B specification rules:

  • At end of frame (not coinciding with end of multiframe), which equals the last octet in the previous frame, the transmitter replaces the octet with /F/ character (K28.7). However, the original octet is encoded if an alignment character was transmitted in the previous frame.
  • At the end of a multiframe, which equals to the last octet in the previous frame, the transmitter replaces the octet with /A/ character (K28.3), even if a control character was already transmitted in the previous frame.

For devices that do not support lane synchronization, only /F/ character replacement is done. At every end of frame, regardless of whether the end of multiframe equals to the last octet in previous frame, the transmitter encodes the octet as /F/ character (K28.7) if it fits the rules above.

Character replacement for scrambled data

The character replacement for scrambled data in the IP core follows these JESD204B specification rules:

  • At end of frame (not coinciding with end of multiframe), which equals to 0xFC (D28.7), the transmitter encodes the octet as /F/ character (K28.7).
  • At end of multiframe, which equals to 0x7C, the transmitter replaces the current last octet as /A/ character (K28.3).

For devices that do not support lane synchronization, only /F/ character replacement is done. At every end of frame, regardless of whether the end of multiframe equals to 0xFC (D28.7), the transmitter encodes the octet as /F/ character (K28.7) if it fits the rules above.

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