146
Agere Systems Inc.
T8302 Internet Protocol Telephone
Advanced RISC Machine (
ARM
)
Data Sheet
July 2001
12 Ethernet 10/100 PHY(s)
(continued)
12.4.3 Status Signals
The signals listed in the following table are accessible via package pins and are described for clarity.
Table 124. Status Signals
12.4.4 Clock and Reset Signals
The signals listed in the following table are accessible via package pins and are described for clarity
.
Table 125. Clock and Reset Signals
12.5 MII Station Management
The primary function of the MII station management is to transfer control and status information about the
10/100 Ethernet transceiver macrocell to a management entity. This function is accomplished by the MDC clock
input that has a maximum frequency of 25 MHz, and with the MDIO signal.
The MII station management interface uses
MDC
and
MDIO
to physically transport information between the PHY
and the MII station management entity.
In the 10/100 Ethernet transceiver macrocell, the
MDIO
pin is implemented as the following three signals:
I
MDIO_IN
I
MDIO_OUT
I
MDIO_HIZ
MDIO_IN
is the information coming from the MAC and is ignored during the
TA
and
DATA
fields for
MDIO
reads.
MDIO_HIZ
will be high except during
MDIO
reads, in which case
MDIO_OUT
is the PHY data. Under no condition
should the input
MDIO_IN
be 3-stated. These can be connected to control an I/O buffer if off-chip access is
required.
Signal
XS
Type
O
Description
Transmit status. This signal indicates transmit activity. Every transmit activity causes a
2.5 s on, 2.5 s off blink.
Link10. This signal indicates good link status for 10 Mbits/s.
Link100. This signal indicates good link status for 100 Mbits/s.
LS10_OK
LS100_OK
O
O
Signal
RMCLK
XLO
Type
I
I
Description
RMCLK is internally tied low, and is unused. It should be left open to avoid possible EMI issues.
Crystal oscillator input. A 25 MHz crystal ±25 ppm should be connected across
XLO
and
XHI
.
Alternately, a 25 MHz external CMOS oscillator can be connected to this input.
Crystal oscillator output.
XHI
O