GTS Ethernet Hard IP User Guide: Agilex™ 5 FPGAs and SoCs

ID 817676
Date 8/04/2025
Public
Document Table of Contents

13.2.1.1. Insert TX Preamble, Start, and SFD

In the TX Datapath the MAC appends an eight-byte preamble that begins with a Start byte (0xFB) to the client frame. If you turn on Link fault generation option, this MAC module also incorporates the functions of the reconciliation sublayer.

The source of the preamble depends on whether you enable the preamble passthrough feature by turning on Enable preamble passthrough in the GTS Ethernet Hard IP parameter editor.

If the preamble pass-through feature is turned on, the client must provide eight preamble bytes (including an SFD byte) on the data bus. The MAC automatically replace the Start Control byte.