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DP83867IS: How to shorten the link up time

g.f.
Guru 15510 points
Part Number: DP83867IS

Hi,

Since the PHY connected to DP83867IS is 10 / 100Base, it takes time to link up to 100Base during auto-negotiation.
But we want to shorten the time of linkup.
I'm thinking of using the Speed Optimization function of DP83867IS to shorten the time to link up.

In my understanding, I could shorten the time by enabling the speed optimization and set the SPEED_OPT_ATTEMPT_CNT value to '00'.
But in the DP83867IS datasheet(snlS504C) page.64 Table 28. Configuration Register 2(CFG2), it seems that bit[11:10] SPEED_OPT_ATTEMPT_CNT is
Read-Only bit field. Is this typo, and is it available to write the value to this bit field?

best regards,
g.f.

best regards,
g.f.

  • 0
    TI__Genius 14300 points

    Hi g.f,

    Yes this is a mistake in the datasheet, bits[11:10] of register 0x14 should be read/write. You can also enable speed optimization through bit 9 and enable enhanced speed optimization mode through bit 8 of this register. Additionally, on startup you can program register 0x9 bits 9 and 8 to 0 to disable gigabit advertisement. 

    Please let me know if you have any other questions, otherwise I'll close this thread.

    Thanks,

    Lucas

    All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and it is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml).

  • 0 in reply to Lucas Wolter
    Guru 15510 points

    Hi Lucas,

    Thank you for the reply.

    I understood about the register 0x14 now.

    I have other question about configuration of gigabit advertisement in register 0x9 bit 9 and 8.
    If I set to 0 to disable gigabit advertisement, will auto-negotiation starts from 100Base?
    So, if there are case that this phy will be connected to 1000Base phy, should I keep this gigabit advertisement enable?
    And should I only setup the speed optimization function to shorten linkup time?

    best regards,
    g.f.

  • +1 in reply to g.f.
    TI__Genius 14300 points

    Hi g.f,

    Yes, your understanding of all the capabilities is correct.

    Thanks,

    Lucas

    All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and it is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml).

  • 0 in reply to Lucas Wolter
    Guru 15510 points

    Hi Lucas,

    Thank you for supporting me.
    I understood.

    best regards,
    g.f.