External Memory Interfaces Agilex™ 7 M-Series FPGA IP User Guide

ID 772538
Date 11/18/2024
Public
Document Table of Contents

3.1.9. User Clock in Different Core Access Modes

The EMIF IP for Agilex™ 7 M-Series devices supports three user access modes.
  • Synchronous fabric clocking, where the EMIF IP provides a user clock.
    • The user clock frequency is limited by the maximum core-to-periphery (C2P) and periphery-to-core (P2C) frequency of 400 MHz.
    • In DDR4, the user clock frequency will be one-quarter of the memory clock frequency ((mem_CK)/4).
    • In DDR5 and LPDDR5, the user clock frequency will be one-eighth of the memory clock frequency ((mem CK)/8).
  • Asynchronous fabric clocking, where you provide the clock to the EMIF IP.
    • The asynchronous user clock can come from any user clock source on the device.
    • The user clock frequency has no dependency on the memory clock (mem_CK).
  • NoC Mode.

The following figures illustrate the different clocking styles available for the Agilex™ 7 M-Series EMIF IP. The NoC mode shown is the simplest NoC mode.

Figure 11. Access Modes

Benefits of Each Access Mode

  • Synchronous fabric clocking is required for DDR4 DIMM or DDR4/DDR5 x40 interfaces.
  • Asynchronous fabric access mode has the lowest latency.
  • NoC mode can achieve the highest bandwidth and efficiency, and has the lowest initiator blockage.