Ethernet Design Example Components User Guide

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ID 683044
Date 12/13/2021
Public

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Document Table of Contents
Document Table of Contents x
1. Time-of-day Clock 2. Time-of-day Synchronizer 3. Packet Classifier 4. Ethernet Design Example Components User Guide Archives 5. Document Revision History for the Ethernet Design Example Components User Guide
1. Time-of-day Clock x
1.1. Release Information 1.2. Resource Utilization 1.3. Configuring the TOD Clock 1.4. Using the TOD Clock 1.5. Interface Signals 1.6. Configuration Registers
1.1. Release Information x
1.1.1. Pulse Per Second Device Speed Grade Support
1.4. Using the TOD Clock x
1.4.1. Adjusting TOD Drift 1.4.2. Adjusting Offset, Jitter, and Wander 1.4.3. Correcting TOD Offset 1.4.4. IOPLL and TOD Setup for Pulse Per Second (Advanced Accuracy Mode)
1.5. Interface Signals x
1.5.1. Avalon Memory-Mapped Signals 1.5.2. Time-of-day Signals 1.5.3. Pulse-Per-Second Signals 1.5.4. Clocking Requirements
2. Time-of-day Synchronizer x
2.1. Release Information 2.2. Resource Utilization 2.3. Configuring the TOD Synchronizer 2.4. Using the TOD Synchronizer 2.5. Interface Signals
2.4. Using the TOD Synchronizer x
2.4.1. Sampling Clock Frequency
3. Packet Classifier x
3.1. Release Information 3.2. Resource Utilization 3.3. Configuring the Packet Classifier 3.4. Interface Signals
3.4. Interface Signals x
3.4.1. Clock and Reset Signals 3.4.2. Avalon® Streaming Interface Signals 3.4.3. Control Signals
1. Time-of-day Clock
2. Time-of-day Synchronizer
3. Packet Classifier
4. Ethernet Design Example Components User Guide Archives
5. Document Revision History for the Ethernet Design Example Components User Guide

1.5.4. Clocking Requirements

  • Expect the clk frequency to be equal or less than 100 MHz.
  • The period_clk must have the same clock source as the timestamping consumer, e.g. MAC. In case the frequency exceeds 156.25 MHz, when OFFSET_JITTER_WANDER_EN is enabled, use the ToD in conjunction with the TOD Synchronizer.
  • For advanced accuracy Pulse per Second feature, IOPLL instantiation is required and must meet the following clocking requirements:
    • The IOPLL reference clock must be driven by TOD period clock or any clock with zero ppm difference from TOD period clock.
    • The IOPLL scan clock must be the same clock connecting to iopll_scan_clk. Set the iopll_scan_clk with any value between 50MHz and 100 MHz. The lower the frequency of the iopll_scan_clk, the longer the IOPLL takes to carry out the phase shift operation.
    • Set the pps_sampling_clk frequency as close as possible to the formula given in the interface description per . Deviation from the formula can affect the accuracy of the PPS signal. However, a few MHz difference is acceptable and still gives an accuracy within 2ns range.
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