- MDIO
Management Data Input/Output, or MDIO, is a bus structure defined for the
Ethernet protocol. MDIO is defined to connectMedia Access Control (MAC) devices withPHY devices, providing a standardized access method to internal registers of PHY devices.These internal registers provide configuration information to the PHY. This bus allows a user to change configuration information during operation, as well as read the PHY's status. It is a standards-driven, dedicated-bus approach that's specified by
IEEE 802.3 . The MDIO interface is implemented by two pins, an MDIO pin and a Management Data Clock (MDC) pin. This standard is available for all speeds of Ethernet.The "Clause 22" MDIO interface can access up to 32 registers, in 32 different devices. A device driving an MDIO bus is called a station management entity (STA), and the device being managed by the STA is called the MDIO Manageable Device (MMD). The STA drives the MDC line. It initiates a command using an MDIO frame and provides the target register address. During a write command, the STA also provides the data. In the case of a read command, the MMD takes over the bus and supplies the STA with the data.
The
802.3ae "Clause 45" interface can access up to 65536 registers in 32 different devices.ee also
*
Medium dependent interface (MDI/MDIX)
*Media Independent Interface (MII)
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