AN983 ETC [List of Unclassifed Manufacturers], AN983 Datasheet - Page 69

• Manufacturer Part Number: AN983
• Description: PCI/miniPCI-to-Ethernet LAN Controller
• Manufacturer: ETC [List of Unclassifed Manufacturers]

8.5.3 FLOW CONTROL IN FULL DUPLEX APPLICATION
Rev. 1.8
The transceiver can operate for either full duplex or half duplex network application. In full duplex,
both transmit and receive can be operated simultaneously. Under full duplex mode, collision (COL)
signal is ignored and carrier sense (CRS) signal is asserted only when the transceiver is receiving.
In half duplex mode, either transmit or receive can be operated at one time. Under half duplex mode,
collision signal is asserted when transmit and receive signals collided and carrier sense asserted
during transmission and reception.
NRZ to NRZI converter then loop-back to the receive path into the input of NRZI to NRZ
converter.
In the 10BASE-T loop-back operation, the data is through transmitting path and loop-back
from the output of the Manchester encoder into the input of Phase Lock Loop circuit of
receive path.
The Auto-Negotiation function is designed to provide the means to exchange information
between the transceiver and the network partner to automatically configure both to take
maximum advantage of their abilities, and both are setup accordingly. The Auto-Negotiation
function can be controlled through bit 12 of PHY register 0.
The Auto-Negotiation exchanges information with the network partner using the Fast Link
Pulses (FLPs) - a burst of link pulses. There are 16 bits of signaling information contained in
the burst pulses to advertise all remote partners’ capabilities, which are determined by PHY,
register 4. According to this information they find out their highest common capability by
following the priority sequence as below:
1. 100BASE-TX full duplex
2. 100BASE-TX half duplex
3. 10BASE-T full duplex
4. 10BASE-T half duplex
and the Auto-Negotiation function will process. Otherwise, the Auto-Negotiation will not
occur until the bit 12 of PHY register 0 is set to 1. When the Auto-Negotiation is disabled,
then the Network Speed and Duplex Mode are selected by programming PHY register 0.
To reduce the power consumption the transceiver is designed with power down feature,
which can save the power consumption significantly. Since the power supply of the
100BASE-TX and 10BASE-T circuits are separated, the transceiver can turn off the circuit of
either the 100BASE-TX or 10BASE-T when the other one of them is operating.
Full Duplex and Half Duplex Operation of Transceiver
Auto-Negotiation Operation
During power-up or reset, if Auto-Negotiation is found enabled then FLPs will be transmitted
Power Down Operation
AN983B
www.admtek.com.tw
ADMtek Inc.
PCI/miPCI Fast Ethernet Controller with integrated PHY
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