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AM4379: PRU MII connections on IDK

user4759028
Prodigy 190 points
Part Number: AM4379
Other Parts Discussed in Thread: TLK105L

Hi,
We are designing a custom board referencing IDKAM437x Schematic 1.4A and require one cpsw ethernet and a pru ethernet for an ethercat application.
We want to reference one of your PHY connections but the first and the second pru-ethernet connections are different.

The connections for the pins of tlk105l differ in connections in the schematics file (sheets 7-8).
1- AM437X_PRUETH0_COL is pulled-down by a 2k2 resistor while AM437X_PRUETH1_COL is directly connected to E24 and rc-45's pin number of.
2- PRUETH1_MDIO is pulled high, PRUETH0_MDIO pulled low

Why there are such differences, while the only different thing seems to be their MDIO Addresses.

Thanks.

  • 0
    TI__Mastermind 42545 points

    Hi,

    The COL pin is used to determine the value for PHY A0 where the default address is 0x01.  The pull down on AM437X_PRUETH0_COL will set the address for PHY0 to 0x00.  The COL pin is used in MLED mode to reflect the link status.  This is connected to the RLINK on the SoC and the LINK LED on the connector.

    There is no pull down on PRUETH0_MDIO.  PRUETH0_MDIO and PRUETH1_MDIO are connected together with zero ohm resistors and R462 acts as a necessary pull up resistor for the MDIO signal.

    Regards, Bill