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DP83867IR: Default value for 0x0086

ACGUY
Guru 11170 points
Part Number: DP83867IR

Hello E2E,

I read out the default register value from address 0x0086 of DP83867IR on our engineering-board.
The value was 17hex. In datasheet says that default value is 77hex.

Which is correct?

Regards,
ACGUY

  • 0
    TI__Mastermind 18425 points
    Hi ACGUY,

    Register 0x86 stores the RGMII TX and RX delay values. These can also be controlled via straps. The default mode when not straps are used is 0x77. When strap resistors are used, this value can change. If you have not connected strap resistors and don't expect the value to change, this might be an indication that something else on the board is causing the strap to change from default value. Most common example is internal pull resistors of the processor connected to the PHY. You can add external resistors to compensate for the such a internal pull or you can just overwrite the value in register 0x86 with the desired value. Please note that this value will need to be written after every power cycle or reset.

    -Regards,
    Aniruddha
  • 0 in reply to Aniruddha Khadye
    Guru 11170 points

    Hello Aniruddha,

    Thank you for advice.
    I could not find that description on pin-strap for RGMII Delay Control from datasheet.
    Which pin is it?

    Regards,
    ACGUY

  • 0 in reply to Aniruddha Khadye
    Guru 11170 points
    Hello Aniruddha,

    Please your advice.

    Regards,
    ACGUY
  • 0 in reply to Aniruddha Khadye
    Guru 11170 points

    Hello Aniruddha,

    Thank you for advice.
    I could not find that description on pin-strap for RGMII Delay Control from datasheet.
    Which pin is it?

    Regards,
    ACGUY

  • 0 in reply to ACGUY
    TI__Mastermind 18425 points
    Hi ACGUY,

    The datasheet has a 4 Level strap pins table which contains information for all strapping pins. There is also tables for RGMII skew which contains information on which strap modes relates to which skew value.

    -Regards,
    Aniruddha