Article ID: 000076387 Content Type: Troubleshooting Last Reviewed: 08/18/2023

Why is the read data value incorrect for the DQS input delay when using the Dynamic Reconfiguration mode in the Intel® Arria® 10 PHYLite IP?

Environment

  • Intel® Quartus® Prime Pro Edition
  • PHY Lite for Parallel Interfaces Intel® Arria® 10 FPGA IP
  • BUILT IN - ARTICLE INTRO SECOND COMPONENT

    Critical Issue

    Description

    When using the Dynamic Reconfiguration mode in the Intel® Arria® 10 PHYLite IP, you may write a value for the DQS input delay to a specific address location.

    However, you may see a different data value for the DQS input delay when reading back from that specific location because the legal range of the DQS input delay isn’t fixed and is dependent on the VCO frequency.

    A typical calibration methodology is to sweep the DQS input delay for pass/fail results. An expected calibration is to increment the DQS Input delay through a valid range and capture the largest value before it passes. Then continue to increment the DQS input delay and capture the smallest value before it fails. The DQS input delay is then set to the mid-point of the above two values.

    However, the entire 10-bit range value for the DQS input delay (i.e. 0X3FF) won’t be available for slower interface frequencies because there exists only a limited number of delay cells where each cell has a Process, Voltage, and Temperature (PVT) dependent fixed delay value. The Intel® Arria® 10 PHYLite circuit caps the DQS Input delay to a legal maximum value.

    Therefore, if you write a value for the DQS input delay greater than the maximum DQS input delay, then you will actually write a value equal to the maximum DQS input delay and you will read back a value equal to the maximum DQS input delay.

    Below is a table showing some select Intel® Arria® 10 PHYLite clock frequencies and the maximum DQS input delay.

    Interface Clock Frequency (MHz)

    VCO Frequency

    User Clock Rate

    Maximum DQS Input Delay

    133

    533.33

    Full-rate (FR)

    0x0FD

    160

    640

    FR

    0x23F

    160

    320

    Half-rate (HR)

    0x100

    320

    320

    HR

    0x0FD

    320

    640

    Quarter-rate (QR)

    0x23D

    640

    640

    QR

    0x23F

    960

    960

    QR

    0x352

    1200

    1200

    QR

    0x3FF

     

    Note: The maximum DQS input delays differ as they depend on the device Process, Voltage, and Temperature (PVT).

    Resolution

    This problem is scheduled to be fixed in a future release of the Intel® Quartus® Prime Pro Edition Software.

    Related Products

    This article applies to 1 products

    Intel® Arria® 10 FPGAs and SoC FPGAs