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DP83867IS: Master/Slave configuration

Atsushi Takahashi
Expert 1415 points
Part Number: DP83867IS

Tool/software:

Hi Team,

Please tell me about Master/Slave configuration.

The customer would like to forcefully change the Master mode resolved by auto-negotiation to Slave mode.

Is the following method correct?

Is auto-negotiation necessary again after step 5?

1) The local PHY (DP83867IS) and link partner use auto-negotiation.

2) The Master/Slave configuration is also determined by auto-negotiation. That is, 0x0009 Bit[12] = 0: Disable Manual Master/Slave Configuration control.

3) During normal communication, the local PHY is set to Slave. That is, 0x000A Bit[14] = 0: Configuration resolved to SLAVE.

4) During communication failure, the local PHY is set to Master. That is, 0x000A Bit[14] = 1: Configuration resolved to MASTER.

5) At this time, the customer tried to write to register 0x0009 Bit[12] = 1, Bit[11] = 0.

6) After that, they read 0x000A, but 0x000A was not changed to Bit[14] = 0.

Best Regards,

  • 0
    TI__Mastermind 39855 points

    Hello,

    If customer would like to forcefully control master/slave, they must enable manual control via Reg 0x9[12]. This would then unlock maneuvering via [11].

    Another note would be to ensure that PHY goes through auto-negotiation with this setting again. If this setting was done after linkup was completed, this process would not work as intended.

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    Expert 1415 points

    Hi Gerome-san,

    Thank you for your reply.

    The customer would like to forcefully change to Slave mode from Master mode after the link is established by auto-negotiation.

    Because although PHY shows link up status, communication error occurs due to Master/Slave mismatch.

    In this case, is it impossible to change via register 0x0009 Bit[12]?

  • 0 in reply to Atsushi Takahashi
    TI__Mastermind 39855 points

    Hello,

    Master/Slave resolution is done using auto-negotiation, so if any configuration of master/slave control is done after link has been established, link will have to be re-established for these settings to take effect. Customer can do this either by replugging cable, or restarting auto-negotiation (Reg 0x0[9]).

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    Expert 1415 points

    Hi Gerome-san,

    Thank you for your reply.

    Register 0x0009 Bit[12] is the bit that disables or enables the manual setting.

    I think that auto-negotiation was not relevant when using manual settings.

    Is my understanding incorrect?

    Is the auto-negotiation process necessary even in the case of manual setting?

  • 0 in reply to Atsushi Takahashi
    TI__Mastermind 39855 points

    Hi Takahashi-san,

    Master/Slave is a part of the auto-negotiation advertisements in this case. When the PHY is communicating with the link partner, one of the items to establish is whose clock is the MDI operating off of.

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    Expert 1415 points

    Hi Gerome-san,

    Thank you for your reply.

    I understood that 0x0009 Bit[12] is advertisements for auto-negotiation.

    Is there a way to forcefully change the Master/Slave mode after the link has been established without rebooting or resetting?

  • 0 in reply to Atsushi Takahashi
    Expert 1415 points

    Hi Gerome-san,

    I have an additional question.

    What is the difference between Register 0x0009 Bit[12] = 0 and Bit[12] = 1?

    If auto-negotiation is required in both cases, I think there is no difference between these.

  • +1 in reply to Atsushi Takahashi
    TI__Mastermind 39855 points

    Hello,

    There is no way to change Master/Slave after link has been establish. You would need to re-link for your new configurations to take effect. 

    Reg 0x9[12] would control whether you as user want to manually control what the DUT is sending during the auto-negotiation process (whether it wants to be master/slave). This would ensure that when the PHY links, it can always be a certain configuration if manual control is enabled.

    Sincerely,

    Gerome