Low Latency 40-Gbps Ethernet IP Core User Guide

ID 683745
Date 3/08/2021
Document Table of Contents

3.2.20. Resets

The LL 40GbE IP core has a single asynchronous reset signal. Asserting this signal resets the full IP core. You must hold the reset signal asserted for ten clk_status clock cycles to ensure proper hold time.

You should not release the 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. Ten clk_status cycles should be sufficient for the fPLL to lock and the reference clock to stabilize.

Table 31.  Asynchronous Reset Signal 

Signal Name





LL 40GbE IP core asynchronous reset signal

In addition, the LL 40GbE IP core has one or two of the following synchronous reset signals:

  • reset_status—Resets the IP core control and status interface, an Avalon-MM interface. Associated clock is the clk_status clock, which clocks the control and status interface.
  • reconfig_reset—Resets the IP core Arria 10 transceiver reconfiguration interface, an Avalon-MM interface. Associated clock is the reconfig_clk, which clocks the Arria 10 transceiver reconfiguration interface. This signal is available only in Arria 10 IP core variations.