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AM4372: Can I use the Microchip KSZ9896C switch with the AM4372 MAC?

Timothy Barr
Genius 3370 points
Part Number: AM4372

Is it possible to use the KSZ9896C  5 port Ethernet switch with the AM4372 EMAC? The KSZ9896C has a GB MAC interface, but I am not sure if there are issues. The device has a sixth port that I have configured as a RGMII interface and have connected it to the proper rgmii2 pins.

  • 0
    TI__Guru 63125 points

    Does the KSZ9896C RGMII port you have connected to AM372 operate as a MAC or PHY. The AM372 RGMII port is operating as a MAC and expects to be connected to a PHY, so the switch needs to have a RGMII port that emulates PHY mode.

    Regards,
    Paul 

  • 0 in reply to peaves
    Genius 3370 points

    As best as I can determine, the RGMII interface on the KSZ9896C is in PHY mode.

  • 0 in reply to Timothy Barr
    TI__Guru 63125 points

    This is not typically the case. Most Ethernet switch ports operate like a MAC and expect a PHY to be connected. Ethernet switches may have one port that can be configured to operate as a PHY. If so, this is typically clearly stated as a feature in the switch datasheet.

    The RGMII port appears to be symmetrical and is with respect to signal voltage and timing. However, there are some optional protocol differences where the PHY sends status information to the MAC in-band on the RX data path. This in-band communications would not be present in a MAC to MAC connection.

    Regards,
    Paul

  • 0 in reply to peaves
    Genius 3370 points

    According the the KSZ9896C data sheet, Port 6 has a PHY or MAC mode capability. The pins on port 6 are labeled as they would be for a PHY, TX is in and RX is out.

  • 0 in reply to Timothy Barr
    TI__Guru 63125 points

    Then you should be able to connect port 6 of the switch to AM4372 the same way you would connect an Ethernet PHY to AM4372. 

    Regards,
    Paul

  • 0 in reply to peaves
    TI__Guru 63125 points

    I forgot to mention, this assumes port 6 of the switch has a MDIO port which can be connected to AM4372 and this MDIO port provides a way for the AM7372 software to configure port 6 as if it were a PHY.

    Regards,
    Paul