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AM3352: DDR Test fail at tDQSS, tLZDQ, SRQdiffR, SRQdiffF using DSO91304A

howard shih
Intellectual 260 points
Other Parts Discussed in Thread: AM3352
  1. Part Number: AM3352

Hi,

We are using U-boot-2018.01. (base on am335x-evm-linux-sdk-src-05.03.00.07.tar.xz)

DDR datasheet

By following the steps described in https://www.ti.com/lit/an/sprack4/sprack4.pdf?ts=1633317767433, we got a set of DDR parameters and updated them into ddr_defs.h, which will be referenced by config_ddr() in board.c.

After system boots up, everything works well. (memtester has no error. CCS DDR_DataTransferCheck and EDMA are passed also.)

However, we can't pass following electronic verification tests.

We are now studying ratio seed parameters (We guess wrong seed might be the reason.)

  • DDR clock frequency      400 MHz
    PHY_INVERT_CLKOUT 0

    Trace Length (inches)
    DDR_CK trace                1       *not sure
    DDR_DQSx trace           0.86  *not sure

    Intermediate values (per byte lane)
    WR DQS                        2        0
    RD DQS                       40      40
    RD DQS GATE             72      40

    Seed values used in CCS code
    DATAx_PHY_RD DQS_SLAVE_RATIO   40
    DATAx_PHY_FIFO_WE_SLAVE_RATIO 59
    DATAx_PHY_WR DQS_SLAVE_RATIO    1

    Register value
    CMDx_PHY_CTRL_SLAVE_RATIO        80

Could you help us to point out the mistakes or give us some hints?

Thanks!

- Howard

  • +1
    TI__Guru* 80240 points

    Howard, you must have the proper trace lengths from your design in order for the spreadsheet to calculate the proper values.  Once this is done, the spreadsheet will calculate the correct values for your board.  If you have a 16bit DDR device with a point to point design, you can use the seed values directly in your software configuration.  Ensure these values are programmed properly.

    Regards,

    James

  • 0 in reply to JJD
    Intellectual 260 points

    Hi JJD,

    We use AM335x_EMIF_Configuration_Tool_v3.xlsx to replace AM335x_DDR_register_calc_tool.XLS and RatioSeed_AM335x_boards.xls and follow DDR fine tune steps. The test is passed.

    Thank you for your help!

    - Howard