40- and 100-Gbps Ethernet MAC and PHY MegaCore Function User Guide

ID 683114
Date 6/15/2022
Public
Document Table of Contents

3.2.21. Resets

The 40-100GbE IP core provides the following two independent reset mechanisms:

  • Asynchronous reset signals—A set of asynchronous reset signals you can assert to reset different parts of the IP core. Use this method to initialize your IP core.
  • Reset registers—A set of register bits you can write to reset different parts of the IP core. This method is available for dynamic reset during operation.
Table 34.  Asynchronous Reset Signals The IP core provides five reset signals to allow independent reset control for all configurations. The MAC and PHY asynchronous reset signals are included in the 40‑100GbE IP Core with adapters and without adapters.

Signal Name

Direction

Description

mac_rx_arst_ST

Input

MAC RX asynchronous reset signal

mac_tx_arst_ST

Input

MAC TX asynchronous reset signal

pcs_rx_arst_ST

Input

PHY PCS RX asynchronous reset signal

pcs_tx_arst_ST

Input

PHY PCS TX asynchronous reset signal

pma_arst_ST

Input

PHY PMA asynchronous reset signal

Note: In any MAC and PHY variation, when you reset the TX MAC you must also reset the TX PCS to avoid transmitting corrupted packets. Therefore, Altera recommends that you reset the IP core with the following conditions:
  • Reset the TX MAC and the TX PCS together (assert pcs_tx_arst_ST and mac_tx_arst_ST simultaneously).
  • Release pcs_tx_arst_ST and mac_tx_arst_ST simultaneously or release pcs_tx_arst_ST after you release mac_tx_arst_ST.
Altera recommends that you release all parts of the 40-100GbE IP core from reset simultaneously.
Note:

Each reset signal must be asserted for at least one clk_status cycle. You should not release any reset signal until after you observe that the reference clock is stable. If the reference clock is generated from an fPLL, wait until after the fPLL locks.