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Original question:

DP83867IR: Mirror Mode and Polarity Correction

DP83867E: Polarity detection and correction

Shota Mago
Expert 7030 points
Part Number: DP83867E

Hi team,

According to this thread, polarity detection and correction feature is supported at DP83867.

  1. When reverse polarity is detected on DP83867's RX side, does its TX side flip output polarity accordingly as there is possibility that TX side is also reversed?
    Or detection result of polarity on RX side doesn't affect to TX side?
  2. Polarity detection and correction seems required by IEEE802.3. Does all Ethernet PHY have this feature?

Best regards,

Shota Mago

  • +1
    TI__Mastermind 31755 points

    Hello,

    The PHY will detect and correct polarity as needed per each channel. 

    Yes, all PHYs that conform to IEEE802.3 should have this.

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    TI__Expert 7030 points

    Hi Gerome,

    Thanks for your reply. Let me clarify your answer.

    Gerome Cacho said:
    The PHY will detect and correct polarity as needed per each channel. 

    Does this mean TX side of DP83867E also have polarity correction? Although this is Microchip's app note, it states "For 10BASE-T links the IEEE 802.3 requires the Ethernet PHY to support autopolarity detection and correction of the received data.". So it seems that polarity detection/correction feature is supported by Rx side.

    Also, what I'd like to confirm is that when Rx side detects reverse polarity, if the device automatically flip polarity of Tx side or not.

    Best regards,

    Shota Mago

  • 0 in reply to Shota Mago
    TI__Mastermind 31755 points

    Hello Shota,

    What speed is the customer looking to use? In 1G, there is no explicit TX and RX on MDI. 

    Is customer seeing an issue where the polarity is being swapped on TX due to RX?

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    TI__Expert 7030 points

    Hi Gerome,

    The customer accepted answer of "all PHYs that conform to IEEE802.3 should have this.".

    So you can close the thread. Thank you so much for your support.

    Best regards,

    Shota Mago