GTS Ethernet Intel® FPGA Hard IP User Guide

ID 817676
Date 10/12/2024
Public
Document Table of Contents

4.4.1.2. Drive the Ethernet Packet on the TX MAC Avalon Streaming Client Interface with Enabled Preamble Passthrough

Drive the eight preamble bytes on the i_tx_data bus when the Preamble Passthrough in the parameter editor is turned on.

Drive the TX MAC fields according to the table below when preamble passthrough is enabled.

  • MII Start of Packet control byte always replaces the first preamble byte.
  • Bits [55:8] are the preamble bits, typically set to the 0x55 value.
  • Bits [7:0] is the last preamble byte. In a standard preamble, it is set to the Start Frame Delimiter 0xD5 value.
Table 27.  Ethernet Frame Field Positions in i_tx_data with Preamble Passthrough Enabled for 10GE/25GE Ports

Attention: 10GE/25GE requires multiple transfer cycle for header data.

The (') symbol in the 10GE/25GE i_tx_data column represents transfer on the subsequent cycle.

The ('') symbol in the 10GE/25GE i_tx_data column represents transfer on the 2nd subsequent cycle.

i_tx_data Ethernet Frame Description
[63:56]'' Custom Preamble [63:56] MII SOP control channel replaces it.
[55:48]'' Custom Preamble [55:48] 0x55
[47:40]'' Custom Preamble [47:40] 0x55
[39:32]'' Custom Preamble [39:32] 0x55
[31:24]'' Custom Preamble [31:24] 0x55
[23:16]'' Custom Preamble [23:16] 0x55
[15:8]'' Custom Preamble [15:8] 0x55
[7:0]'' Custom Preamble [7:0] 0xD5 (SFD)
[63:56]' Dest Addr[47:40] N/A
[55:48]' Dest Addr[39:32] N/A
[47:40]' Dest Addr[31:24] N/A
[39:32]' Dest Addr[23:16] N/A
[31:24]' Dest Addr[15:8] N/A
[23:16]' Dest Addr[7:0] N/A
[15:8]' Src Addr[47:40] When you turn on Source Address Insertion, content is replaced by the source address that is configured in the txmac_saddr register unless i_tx_skip_crc is high.
[7:0]' Src Addr[39:32]
[63:56] Src Addr[31:24]
[55:48] Src Addr[23:16]
[47:40] Src Addr[15:8]
[39:32] Src Addr[7:0]
[31:24] Length/Type[15:8] N/A
[23:16] Length/Type[7:0] N/A
[15:0] N/A