AM79C940JC/W AMD [Advanced Micro Devices], AM79C940JC/W Datasheet - Page 19

• Manufacturer Part Number: AM79C940JC/W
• Manufacturer: AMD [Advanced Micro Devices]

PIN DESCRIPTION
Network Interfaces
The MACE device has five potential network inter-
faces. Only one of the interfaces that provides physical
network attachment can be used (active) at any time.
Selection between the AUI, 10BASE-T, DAI or GPSI
ports is provided by programming the PHY Configura-
tion Control register. The EADI port is effectively active
at all times. Some signals, primarily used for status
reporting, are active for more than one single interface
(the CLSN pin for instance). Under each of the descrip-
tions for the network interfaces, the primary signals
which are unique to that interface are described.
Where signals are active for multiple interfaces, they
are described once under the interface most appropri-
ate.
Attachment Unit Interface (AUI)
CI+/CI
Control In (Input)
A differential input pair, signaling the MACE device that
a collision has been detected on the network media, in-
dicated by the CI inputs being exercised with 10 MHz
pattern of sufficient amplitude and duration. Operates
at pseudo-ECL levels.
Notes:
1. PORTSEL [1–0] and ENPLSIO are located in the PLS Configuration Control register (REG ADDR 14).
2. This pin should be externally terminated, if unused, to reduce power consumption.
SLEEP
SLEEP
0
1
1
1
1
1
0
1
1
1
1
1
PORTSEL
PORTSEL
[1-0]
[1-0]
XX
XX
XX
XX
00
01
10
00
01
10
11
11
ENDPLSIO
ENDPLSIO
TXDAT + Configuration
TXDAT – Configuration
X
X
1
1
1
1
0
1
1
1
1
0
Am79C940
Sleep Mode
AUI
10BASE–T
DAI Port
GPSI
Status Disabled
Sleep Mode
AUI
10BASE–T
DAI Port
GPSI
Status Disabled
Interface Description
Interface Description
DI+/DI
Data In (Input)
A differential input pair to the MACE device for receiv-
ing Manchester encoded data from the network.
Operates at pseudo-ECL levels.
DO+/DO
Data Out (Output)
A differential output pair from the MACE device for
transmitting Manchester encoded data to the network.
Operates at pseudo-ECL levels.
Digital Attachment Interface (DAI)
TXDAT+/TXDAT–
Transmit Data (Output)
When the DAI port is selected, TXDAT are configured
as a complementary pair for Manchester encoded data
output from the MACE device, used to transmit data to
a local external network transceiver. During valid trans-
mission (indicated by TXEN low), a logical 1 is indi-
cated by the TXDAT+ pin being in the high state and
TXDAT– in the low state; and a logical 0 is indicated by
the TXDAT+ pin being in the low state and TXDAT– in
the high state. During idle (TXEN high), TXDAT+ will be
in the high state, and TXDAT– in the low state. When
the GPSI port is selected, TXDAT+ will provide NRZ
data output from the MAC core, and TXDAT– will be
held in the LOW state. Operates at TTL levels. The
operations of TXDAT+ and TXDAT– are defined in the
following tables:
High Impedance
High Impedance (Note 2)
High Impedance (Note 2)
TXDAT+ Output
TXDAT+ Output
High Impedance (Note 2)
High Impedance
High Impedance
High Impedance
TXDAT– Output
LOW
High Impedance
Pin Function
Pin Function
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