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DP83869HM: Queries on Strap Configuration and Two Supply Mode Configuration

Harikrishnan Thangamani
Prodigy 60 points
Part Number: DP83869HM


Hi Everyone,

Application of the device: 100BASE-TX and 1000BASE-T Ethernet Interface (SGMII to Copper Interface)

Strap Configuration Queries:

Need Strap Setting Details for Forced 1000M MDI Mode and Forced 10M MDI Mode

Two Supply Mode Query:

As per Datasheet, Pin No 23 (JTAG_TMS) has to be pulled low to use the Two Supply Mode. Can anyone confirm this ?

Please clarify my doubts as soon as possible.

Regards,

Harikrishnan T

  • +1
    TI__Mastermind 40275 points

    Hello,

    There is no strap for dictating two vs three supply mode. This is a typo in the datasheet, and we will look to correct in future revision.

    For these specific MDI settings, there are no strap settings to accomplish these. The only way to accomplish this is via register writes. However, it is our recommendation that all communication go through auto-negotiation and there should be no part of signal chain that has forced communication.

    Sincerely,

    Gerome

  • 0
    Prodigy 60 points

    Hi Gerome,

    I need some more clarification on trailing reply.

    My requirement is to disable the auto-negotiation feature and the speed has to be configured.

    From Strap Settings in Datasheet, To disable the auto-negotiation feature LED_0 Pin (Pin No. 47) has to be strapped high by 2.49K Pull Up Resistor to VDDIO Rail.

    The above point is from my understanding.

    Speed can be forced by BCMR Register (Offset : 0h) Bit 13 and Bit 12 for auto-negotiation.

    I just want to know, Auto-negotiation Feature and Speed can be configured by BCMR Register. In that case Do we have to provide strap setting externally on Pin No 45, 46, 47 ?

    If Hardstrap Setting has to be given , As per Table 9-11 in datasheet Do I have to set as 1 0 0 (or) 1 0 1 for LED_0, LED_2, LED_1 Pins Respectively ?

    Please resolve my query at the earliest.

    Regards,

    Harikrishnan T

  • +1 in reply to Harikrishnan Thangamani
    TI__Mastermind 40275 points

    Hello,

    Allow me to enhance my previous message. 1G forced communication cannot occur due to the standard. For 1G communication, it must be auto-negotiated.

    Pins 45,6,7 do not independently control one portion or another of the auto-negotiation/speed/duplex process. The combination of these will determine speed/duplex/auto-negotiation status of the PHY.

    For auto-negotiation modification, please do with register writes.

    Sincerely,

    Gerome