AM79C971VCW Advanced Micro Devices, AM79C971VCW Datasheet - Page 25

• Manufacturer Part Number: AM79C971VCW
• Description: PCnet-FAST Single-Chip Full-Duplex 10/100 Mbps Ethernet Controller for PCI Local Bus
• Manufacturer: Advanced Micro Devices

If the MII port is not selected, the RX_DV pin can be left
floating.
RX_ER
Receive Error
RX_ER is an input that indicates that the MII trans-
ceiver device has detected a coding error in the receive
frame currently being transferred on the RXD[3:0] pins.
When RX_ER is asserted while RX_DV is asserted, a
CRC error will be indicated in the receive descriptor for
the incoming receive frame. RX_ER is ignored while
RX_DV is deasserted. Special code groups generated
on RXD while RX_DV is deasserted are ignored (e.g.,
Bad SSD in TX and IDLE in T4). RX_ER transitions are
synchronous to RX_CLK rising edges.
Note: The RX_ER pin is multiplexed with the RXDAT
pin.
When RST is active, RX_ER is an input for NAND tree
testing.
If the MII port is not selected, the RX_ER pin can be left
floating.
MDC
Management Data Clock
MDC is a non-continuous clock output that provides a
timing reference for bits on the MDIO pin. During MII
management port operations, MDC runs at a nominal
frequency of 2.5 MHz. When no management opera-
tions are in progress, MDC is driven LOW. The MDC is
derived from the external 20-MHz crystal.
If the MII port is not selected, the MDC pin can be left
floating.
MDIO
Management Data I/O
MDIO is the bidirectional MII management port data
pin. MDIO is an output during the header portion of the
management frame transfers and during the data por-
tions of write transfers. MDIO is an input during the
data portions of read data transfers. When an operation
is not in progress on the management port, MDIO is not
driven. MDIO transitions from the Am79C971 controller
are synchronous to MDC Falling edges.
If the PHY is attached through an MII physical connec-
tor, then the MDIO pin should be externally pulled down
to V
board, then the MDIO pin should be externally pulled
up to V
When RST is active, MDIO is an input for NAND tree
testing.
SS
CC
with a 10-k
with a 10-k
5% resistor. If the PHY is on
5% resistor
Input/Output
Output
Input
Am79C971
Attachment Unit Interface
CI
Collision In
CI is a differential input pair signaling the Am79C971
controller that a collision has been detected on the net-
work media, indicated by the CI inputs being driven
with a 10-MHz pattern of sufficient amplitude and pulse
width to meet ISO 8802-3 (IEEE/ANSI 802.3) stan-
dards. CI operates at pseudo ECL levels.
If the CI
gether.
DI
Data In
DI is a differential input pair to the Am79C971 control-
ler carrying Manchester encoded data from the net-
work. DI operates at pseudo ECL levels.
If the DI pins are not used, they should be tied to-
gether.
DO
Data Out
DO is a differential output pair from the Am79C971
controller for transmitting Manchester encoded data to
the network. DO operates at pseudo ECL levels.
If the AUI is not used, DO should be left floating for
minimum power consumption.
10BASE-T Interface
RXD
10BASE-T Receive Data
RXD are 10BASE-T port differential receivers. If the
10BASE-T interface is not used in a design, RXD+ and
RXD- should be connected to each other.
TXD
10BASE-T Transmit Data
TXD are 10BASE-T port differential drivers.
TXP
10BASE-T Pre-Distortion Control
These outputs provide transmit pre-distortion control in
conjunction with the 10BASE-T port differential drivers.
General Purpose Serial Interface
CLSN
Collision
CLSN is an input that indicates a collision has occurred
on the network.
Note: The CLSN pin is multiplexed with the COL pin.
When RST is active, CLSN is an input for NAND tree
testing.
pins are not used, they should be tied to-
Output
Output
Output
Input
Input
Input
Input
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