KS8001L データシートの表示（PDF） - Micrel
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KS8001L Datasheet PDF : 46 Pages
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Micrel
KSZ8001
SMII Signal Definition
SMII is composed of two signals per port, a global synchronization signal, and a global 125MHz reference clock. All signals are
synchronous to the clock. All SMII I/F uses a common 125MHz reference clock and SYNC signals that are synchronous to the
reference clock. There are two signals in SMII from MAC-to-PHY for each port (TXD and TxSYNC), and one signal per port from
PHY-to-MAC (RXD).
The Serial Media Independent Interface (SMII) is designed to satisfy the following requirements:
• Convey complete MII information between a 10/100 PHY and MAC with two pins per port.
• Allow a multi-port MAC/PHY communication with one system clock.
• Operate in both half and full duplex.
• Per packet switching between 10Mbit and 100Mbit data rates.
• Allow direct MAC-to-MAC communication.
SMII Signals
Signal Name
RX
TX
SYNC
Clock
From
PHY
MAC
MAC
System
To
MAC
PHY
PHY
MAC&PHY
Use
Receive Data and Control
Transmit Data and Control
Synchronization
Synchronization
Receive Path
Receive data and control information are signaled in ten bit segments. In 100Mbit mode, each segment represents a new byte of
data. In 10Mbit mode, each segment is repeated ten times; therefore, every ten segments represent a new byte of data. The MAC
can simply any one of every 10 segment ion 10Mbit mode.
Segment boundaries are delimited by SYNC. The MAC continuously generates a pulse on SYNC every 10 clocks.
Receive Sequence Diagram
RX_CLK
RX_SYNC
RX
CRS
RX_DV
RXD0
RXD1
RXD2
RXD3
RXD4
RXD5
RXD6
RXD7
RX contains all of the information found on the receive path of the standard MII.
Bits
Purpose
CRS
Carrier Sense – identical to MII, except that it is not an asynchronous signal
RX_DV
Receive Data Valid – identical to MII
RXD7-0
Encoded Data, see the RXD0-7 Encoding table
RX – Bit Description
RXD7-0 are used to convey packet data, RX_ER, and PHY status. The MAC can infer the meaning of RXD on a segment-by-basis
by encoding the two control bits.
June 2009
Revision 1.04
17
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