Article ID: 000079995 Content Type: Troubleshooting Last Reviewed: 08/21/2023

Why is the reported center DQS enable calibration results outside of the start-end range when the runtime calibration report is enabled for the HPS external memory controller?


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    Due to a problem in the HPS SDRAM Controller calibration algorithm generated by the Altera SoC Embedded Design Suite for Cyclone® V SoC and Arria® V SoC devices, the DQS enable center report may be greater than both start and end reports.

    The calibration algorithm finds the maximum and minimum parameters for a number of delays and picks the center value.  For DQS enable, both the start and end reports have been normalized to VFIFO_SIZE, but the center report is not normalized, so it may appear to be outside of the range start: end.

    VFIFO_SIZE is set to 16 for Cyclone® V and Arria® V devices.

    Note:  To enable this report, the macro RUNTIME_CAL_REPORT must be set, which reports the calibration process results to the stdout (usually a UART).


    The center VFIFO report should be divided by 16 which is VFIFO_SIZE and the remainder is the VFIFO delay.

    For example:
    SEQ.C: DQS Enable ; Group 0 ; Rank 0 ; Start  VFIFO  6 ; Phase 1 ; Delay  4
    SEQ.C: DQS Enable ; Group 0 ; Rank 0 ; End    VFIFO  7 ; Phase 0 ; Delay 18
    SEQ.C: DQS Enable ; Group 0 ; Rank 0 ; Center VFIFO 22 ; Phase 5 ; Delay  3

    The true center VFIFO value is 22 % 16 = 6 which is between 6 and 7 as expected.

    The generated preloader code may be modified to make this change as follows:

    1. Open <preloader>\uboot-socfpga\board\altera\socfpga\sdram\sequencer.c

    2. Search for the following line:
    RPRINT("DQS Enable ; Group %lu ; Rank %lu ; Center VFIFO %2li ; Phase %li ; Delay %2li", grp, sr, v, p-1, d);

    3. Replacing with this line:
    RPRINT("DQS Enable ; Group %lu ; Rank %lu ; Center VFIFO %2li ; Phase %li ; Delay %2li", grp, sr, (v % VFIFO_SIZE), p-1, d);

    4. Regenerate your Preloader by running:

    make clean; make.

    This problem is fixed starting with the Altera SoC Embedded Design Suite 15.1.

    Related Products

    This article applies to 5 products

    Cyclone® V SX SoC FPGA
    Arria® V ST SoC FPGA
    Arria® V SX SoC FPGA
    Cyclone® V SE SoC FPGA
    Cyclone® V ST SoC FPGA