Ethernet - PHY, MAC and MII Basics

PHY is the physical interface transceiver, which implements the physical layer. Including MII/GMII (Media Independent Interface) sublayer, PCS (Physical Coding Sublayer), PMA (Physical Medium Attachment) sublayer, PMD (Physical Medium Dependent) sublayer, MDI sublayer. It defines the electrical and optical signals, line status, clock reference, data encoding and circuits required for data transmission and reception, and provides standard interfaces to data link layer devices. The physical layer chip is called PHY.MAC MAC is the abbreviation of Media Access Control, that is, the sublayer protocol of Media Access Control. The protocol is located in the lower half of the data link layer in the OSI seven-layer protocol, and is mainly responsible for controlling and connecting the physical medium of the physical layer. When sending data, the MAC protocol can judge in advance whether the data can be sent. If it can be sent, it will add some control information to the data, and finally send the data and control information to the physical layer in a specified format; when receiving data, MAC The protocol first judges whether there is a transmission error in the input information, and if there is no error, the control information is removed and sent to the LLC layer. The Ethernet MAC is defined by the IEEE-802.3 Ethernet standard.MII Ethernet IO MII is Media Independent Interface, also called Media Independent Interface. It is an Ethernet industry standard defined by IEEE-802.3. It includes a data interface, and a management interface between the MAC and the PHY. The data interface consists of two independent channels for the transmitter and receiver. Each channel has its own data, clock and control signals. A total of 16 signals are required for the MII data interface. The management interface is a two-signal interface: one is a clock signal and the other is a data signal. Through the management interface, upper layers can monitor and control the PHY.DC-DC isolation type