External Memory Interfaces Intel® Agilex™ 7 F-Series and I-Series FPGA IP User Guide

ID 683216
Date 4/03/2023

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11.3. Timing Issue Characteristics

The PHY and controller combinations autogenerate timing constraint files to ensure that the PHY and external interface are fully constrained and that timing is analyzed during compilation. However, timing issues can still occur. This topic discusses how to identify and resolve any timing issues that you may encounter.

Timing issues typically fall into two distinct categories:

  • FPGA core timing reported issues
  • External memory interface timing issues in a specific mode of operation or on a specific PCB

Timing Analyzer reports timing issues in two categories: core to core and core to IOE transfers. These timing issues include the PHY and PHY reset sections in the Timing Analyzer Report DDR subsection of timing analysis. External memory interface timing issues are specifically reported in the Timing Analyzer Report DDR subsection, excluding the PHY and PHY reset. The Report DDR PHY and PHY reset sections only include the PHY, and specifically exclude the controller, core, PHY-to-controller and local interface. Intel® Quartus® Prime timing issues should always be evaluated and corrected before proceeding to any hardware testing.

PCB timing issues are usually Intel® Quartus® Prime timing issues, which are not reported in the Intel® Quartus® Prime software, if incorrect or insufficient PCB topology and layout information is not supplied. PCB timing issues are typically characterized by calibration failure, or failures during user mode when the hardware is heated or cooled. Further PCB timing issues are typically hidden if the interface frequency is lowered.