Low Latency Ethernet 10G MAC Intel® FPGA IP User Guide: Agilex™ 5 FPGAs and SoCs

ID 813663
Date 10/07/2024
Public
Document Table of Contents

6.10.1. Calculating PHY Total Latency

The total latency for PHY IP consists of three components:
Table 42.  Total Datapath Latency Components
Datapath Latency Description
Deterministic Latency Deterministic Latency (DL) is the latency delay between the soft PCS and PMA. This latency delay needs to be added and written to the static timing adjustment register. Refer to Calculating Deterministic Latency.
Soft PCS For 1G/2.5G (MBASE), the soft PCS latency value is calculated and presented on the gmii16b_rx_latency and gmii16b_tx_atency output ports. In this mode, the soft PCS latency values are calculated and updated in registers 0x1C to 0x1F.

For 10M/100M/1G/2.5G/5G/10G (USXGMII), the soft PCS latency value is calculated and updated in the xgmii_tx_latency and xgmii_rx_latency output ports.

These ports must be connected to the path delay input ports. Refer to IEEE 1588v2 Interfaces

PMA PMA delay is the delay needed by the PMA layer to serialize parallel data. This delay is in numbers of UI and needs to be added and written to the static timing adjustment register. Refer to Calculating Deterministic Latency.