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AM6442: How to use the DDR Subsystem Register Configuration in SysConfig Tool

Daisuke Maeda
Guru 20425 points

Part Number: AM6442
Other Parts Discussed in Thread: SYSCONFIG

Is there documentation on how to use the DDR Subsystem Register Configuration in SysConfig Tool?

Our customer wants to know how to configure some of the settings in the DDR Subsystem Register Configuration in SysConfig Tool. They especially want to know how to configure the settings for VREF Control.

Could you tell me how to configure the settings for VREF Control in the tool for AM64x/AM243x?

By the way, more information can be found for J7. The information for various settings in the DDRSS Register Configuration Tool (Spreadsheet) can be found in the documentation (SPRACU8).

www.ti.com/.../spracu8a.pdf

Best regards,

Daisuke

  • +1
    TI__Guru* 95181 points

    Daisuke, there shouldn't be a need to change the VREF settings from the default in the tool.  This value eventually gets changed during the DDR initialization and training phase of boot.   

    In fact, most parameters will remain as default for max frequency configurations.  The only thing to maybe change is the system configuration parameters.  Most parameters have popup tool tips to help configure that specific parameter.  

    Regards,

    James

  • 0 in reply to JJD
    Guru 20425 points

    Hi James-san,

    Thank you for your reply.

    JJD said:
    there shouldn't be a need to change the VREF settings from the default in the tool.  This value eventually gets changed during the DDR initialization and training phase of boot. 

    What is the case that there is a need to change the VREF settings from the default in the tool?

    Our customer wants to be clear that there is really not a need to change the VREF settings from the default in the tool for their DDR4 design.

    Best regards,

    Daisuke

  • 0 in reply to Daisuke Maeda
    TI__Guru**** 226655 points

    Hello Daisuke

    Thank you for the inputs.

    Please expect a delay in response due to the US holidays.

    Regards,

    Sreenivasa

  • +1 in reply to Kallikuppa Sreenivasa
    TI__Guru* 95181 points

    The VREF setting is just the initial setting that the training algorithm starts with.  It should be determined based on the drive strength and termination set.  As an example, for writes, if the default output driver impedance is set to 40ohm, and the termination in the memory is set to 40ohm, the ideal VREF is:

    (VOH - VOL)/2+VOL = (1.2-0.6)/2+0.6=0.9V which is 75% of VOH.  

    The values for various drive strength and termination settings can also be obtained from the DDR datasheet.

     

    The default values in the tool don't line up exactly to this.  I will make that adjustment in the next revision.  In actuality, any setting around 75% should be fine as this value gets trained to an optimal reference voltage.

    Regards,

    James

  • 0 in reply to JJD
    Guru 20425 points

    Hi James-san,

    Thank you for your reply. Sorry for the late reply.

    Best regards,

    Daisuke