
Chapter 2
Signal Descriptions
31
24674
Rev. 3.00
April 2003
AMD-8111 HyperTransport I/O Hub Data Sheet
AMD Preliminary Information
2.9
MII Interface
Table 9.
MII Interface Pin Descriptions
Pin Name and Description
I/OCell
Type
I
Power
Plane
VDD_
IOX
During
Reset
After
Reset
During
S1:S2
During
S3:S5
MII_TX_CLK.
MII Transmit Clock. MII_TX_CLK is a
continuous clock input that provides the timing reference
for the transfer of the MII_TX_EN and MII_TXD[3:0]
signals. MII_TX_CLK must provide a nibble rate clock
(25% of the network data rate). Hence, an MII transceiver
operating at 10 Mbit/s must provide a MII_TX_CLK
frequency of 2.5 MHz and an MII transceiver operating at
100 Mbit/s must provide a MII_TX_CLK frequency of 25
MHz.
MII_TXD[3:0].
MII Transmit Data. MII_TXD[3:0] is the
nibble-wide MII transmit data bus. Valid data is generated
on MII_TXD[3:0] on every MII_TX_CLK rising edge while
MII_TX_EN is asserted. While MII_TX_EN is deasserted,
MII_TXD[3:0] values are driven Low. MII_TXD[3:0]
transitions synchronous to MII_TX_CLK rising edges.
MII_TX_EN.
MII Transmit Enable. MII_TX_EN indicates
when valid transmit nibbles are presented on the MII. While
MII_TX_EN is asserted, MII_TXD[3:0] data are generated
on MII_TX_CLK rising edges. MII_TX_EN is asserted with
the first nibble of preamble and remains asserted
throughout the duration of a packet until it is deasserted
prior to the first MII_TX_CLK following the final nibble of the
frame. MII_TX_EN transitions synchronous to MII_TX_CLK
rising edges.
MII_COL.
MII Collision. MII_COL is an input that indicates
that a collision has been detected on the network medium.
MII_CRS.
MII Carrier Sense. MII_CRS is an input that
indicates that a non-idle medium, due either to transmit or
receive activity, has been detected.
MII_RX_CLK.
MII Receive Clock. MII_RX_CLK is a clock
input that provides the timing reference for the transfer of
the MII_RX_DV, MII_RXD[3:0], and MII_RX_ER signals.
MII_RX_CLK must provide a nibble rate clock (25% of the
network data rate). Hence, an MII transceiver operating at
10 Mbit/s must provide an MII_RX_CLK frequency of 2.5
MHz and an MII transceiver operating at 100 Mbit/s must
provide an MII_RX_CLK frequency of 25 MHz. When the
external PHY switches the MII_RX_CLK and MII_TX_CLK,
it must provide glitch-free clock pulses.
O
VDD_
IOX
Low
Low
Func.
Func.
O
VDD_
IOX
Low
Low
Func.
Func.
I
VDD_
IOX
VDD_
IOX
I
I
VDD_
IOX