mdio_mdio是什么缩写_sgmii和serdes的区别

ContentsMDIO History

Management Data Input/Output, or MDIO, is a 2-wire serial bus that is used to manage PHYs or physical layer devices in media access controllers (MACs) in Gigabit Ethernet equipment. The management of these PHYs is based on the access and modification of their various registers.

MDIO was originally defined in Clause 22 of IEEE RFC802.3. In the original specification, a single MDIO intece is able to access up to 32 registers in 32 different PHY devices. These registers provide status and control information such as: link status, speed ability and selection, power down for low power consumption, duplex mode (full or half), auto-negotiation, fault signaling, and loopback.

To meet the needs the expanding needs of 10-Gigabit Ethernet devices, Clause 45 of the 802.3ae specification provided the following additions to MDIO:

Ability to access 65,536 registers in 32 different devices on 32 different ports

Additional OP-code and ST-code for Indirect Address register access for 10 Gigabit Ethernet

End-to-end fault signaling

Multiple loopback points

Low voltage electrical specification

Theory of Operation

The MDIO bus has two signals: Management Data Clock (MDC) and Managment Data Input/Ouput (MDIO).

MDIO has specific terminology to define the various devices on the bus. The device driving the MDIO bus is identified as the Station Management Entity (STA). The target devices that are being managed by the MDC are referred to as MDIO Manageable Devices (MMD).

The STA initiates all communication in MDIO and is responsible for driving the clock on MDC. MDC is specified to have a frequency of up to 2.5 MHz.

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