RTL8201E(L)
Datasheet
8.1. MII and Management Interface
8.1.1. Data Transition
To set the RTL8201E(L) for MII mode operation, pull the COL/SNI pin low.
The MII (Media Independent Interface) is an 18-signal interface (as described in IEEE 802.3u) supplying
a standard interface between the PHY and MAC layer. This interface operates at two frequencies –
25MHz and 2.5MHz – to support 100Mbps/10Mbps bandwidth for both transmit and receive functions.
Transmission
The MAC asserts the TXEN signal. It then changes byte data into 4-bit nibbles and passes them to the
PHY via TXD[3:0]. The PHY will sample TXD[3:0] synchronously with TXC – the transmit clock signal
supplied by PHY – during the interval TXEN is asserted.
Reception
The PHY asserts the RXEN signal. It passes the received nibble data RXD[3:0] clocked by RXC. CRS
and COL signals are used for collision detection and handling.
In 100Base-TX mode, when the decoded signal in 5B is not IDLE, the CRS signal will assert. When 5B is
recognized as IDLE it will be de-asserted. In 10Base-T mode, CRS will assert when the 10M preamble
has been confirmed and will be de-asserted when the IDLE pattern has been confirmed.
The RXDV signal will be asserted when decoded 5B are /J/K/ and will be de-asserted if the 5B are /T/R/
or IDLE in 100Mbps mode. In 10Mbps mode, the RXDV signal is the same as the CRS signal.
The RXER (Receive Error) signal will be asserted if any 5B decode errors occur, e.g., an invalid J/K,
invalid T/R, or invalid symbol. This pin will go high for one or more clock periods to indicate to the
reconciliation sublayer that an error was detected somewhere in the frame.
Note: The RTL8201E(L) does not use a TXER signal. This does not affect the transmit function.
Single-Chip/Port 10/100 Fast Ethernet PHYceiver
with Auto MDIX
18
Track ID: JATR-1076-21 Rev. 1.3
REALTEK [ Realtek Semiconductor Corp. ]
