W3100A Datasheet, PDF (48/63 Pages) List of Unclassifed Manufacturers – i2Chip W3100A

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5. Physical Layer Interface
W3100A is used for linking with an Ethernet Physical Layer Device (RealTek RTL8201, National
DP83843, SMSC 83C180, 83C183, LevelOne LXT905, etc.). Such Physical Layer Devices generally use
the Media Interface (MI) for configuration and the Media Independent Interface (MII) for data transfer
when interfacing with the Ethernet MAC Layer.
5.1 Media Interface (MI)
The MI is the serial I/F for reading/writing the internal register of the Physical Layer Device to set up or
check the configuration of the Physical Layer Device, and its pin is generally denoted as MDC or MDIO.
Since the W3100A does not configure or check the configuration of the Physical Layer Device through the
MI, the systems equipped with the W3100A configure the Physical Layer Device using its pin (in general,
SPEED, DUPLEX, Auto Negotiate, etc.), so that the W3100A can refer to the configuration status through
the W3100A pins (/LINK, /SERIAL, /FDPLX). In other words, /LINK, /SERIAL, and /FDPLX pins of the
W3100A must be connected to reflect the status of the Physical Layer Device. In general, the Physical
Layer Device reports the network configuration status using the LED Pins, which are connected with the
/LINK, /SERIAL, and /FDPLX Pin of the W3100A.
Besides, depending on the systems, it may be necessary for the MCU to configure or check the
configuration of the Physical Layer Device, in which case the MCU must access the Physical Layer Device
directly through the MI.
5.2 Media Independent Interface (MII)
The MII handles the data transfer between the W3100A and the Physical Layer Device.
The MII is composed of TX_CLK, TXE, and TXD[0:3] signals for sending data and RX_CLK, RXDV,
RXD[0:3], and COL signals for receiving data.
When sending data from the W3100A, TXE and TXD[0:3] are output in synchronization with the falling
edges of TX_CLK input from the Physical Layer Device because Physical Layer Devices generally
recognize the rising edges of TX_CLK.
When receiving data, in general, the Physical Layer Devices output RXDV, RXD[0:3], and COL signals in
synchronization with the falling edges of RX_CLK, so the W3100A recognizes the signals at the rising
edges of RX_CLK.
There are serial MII that use 1-bit data signals and nibble MII that use 4-bit data signals.
5.2.1 serial MII
This mode is the I/F for 10Mbps Physical Layer Devices, and is composed of 1-bit TXD and RXD.
TX_CLK and RX_CLK use a 10MHz cycle.
When linking the W3100A with the Physical Layer Device in this mode, RXD and TXD of the Physical
Layer Device must be connected to RXD[0] and TXD[0] of the W3100A.
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