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TMDSCNCD28388D: Question about LINKACT0 and LINKACT1

Green Deng
Expert 4490 points
Part Number: TMDSCNCD28388D

Dear team:

Does the Note in above picture means:

The indicators LINKACT0 and LINKACT1 in Table 31-9 do not support 10M/100M Ethernet, but only support Gigabit Ethernet?

Btw: The PHY used by TMDSCNCD28388D is DP83822 Robust, Low Power 10/100 Mbps Ethernet Physical Layer Transceiver.

Best regards

  • 0
    TI__Mastermind 38275 points

    Hi Green,

    Green Deng said:

    Does the Note in above picture means:

    The indicators LINKACT0 and LINKACT1 in Table 31-9 do not support 10M/100M Ethernet, but only support Gigabit Ethernet?

    No I don't think this is what is meant, but let me discuss internally and confirm. I believe that 'EtherCAT link status through MII option' is something different than using the LINKACT signals.

    Please note the DP83822 comments in the Beckhoff AN below. LED_LINK of DP83822 is used for link detection (LED_0) connected to F2838x ESC_PHYx_LINKSTATUS in ControlCard schematic.

    https://download.beckhoff.com/download/document/io/ethercat-development-products/an_phy_selection_guidev2.6.pdf

    Best,

    Kevin

  • 0 in reply to Kevin Allen18
    TI__Expert 4490 points

    Thank you Kevin, and looking forward to your confirmation

  • +1 in reply to Green Deng
    TI__Mastermind 38275 points

    Hi Green,

    There is a typo in the note, it should be MI (Management Interface) not MII. These are two different things and the names are very similar which makes it confusing. I believe MI is a portion of the MII interface actually.

    • MI (Management Interface) interface is MDIO/MCLK signals that connect to the PHYs shown above
    • MII interface is the complete interface between the ESC and PHYs
      • i.e. MII_Tx/Rx signals, enable signals, MI signals, etc.

    Regarding the note, we do support the MI interface, but do NOT support Link Status through MI (disabled in F2838x ESC itself). Instead use the LINKACT (ESC_LED_LINKx_ACTIVE) and/or PHY MII_LINK (ESC_PHYx_LINKSTATUS) signals for this purpose.

    I've taken an action to clean-up our EtherCAT documentation in the TRM related to MII and MI.

    Best,

    Kevin