AN985B/BX
Functional Descriptions
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 receiving path.
7.4.2.6
Full Duplex and Half Duplex Operation of Transceiver
The transceiver can operate for either full duplex or half duplex network application. In full duplex, both
transmission and reception 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 transmission or reception can be operated at one time. Under half duplex mode,
collision signal is asserted when transmitted and received signals collided and carrier sense asserted during
transmission and reception.
7.4.2.7
Auto-Negotiation Operation
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
During power-up or reset, if Auto-Negotiation is found enabled, FLPs will be transmitted 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, the Network Speed and Duplex Mode are selected by programming PHY
register 0.
7.4.2.8
Power Down Operation
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 is operating.
7.4.3
Flow Control in Full Duplex Application
The PAUSE function operation is used to inhibit transmission of data frames for a specified period of time. The
AN985B/BX supports full duplex protocol of IEEE802.3x. To support the PAUSE function, the AN985B/BX
implements the MAC Control Sub-layer functions to decode the MAC Control frames received from MAC control
clients and execute the relative requests accordingly. When the Full Duplex mode and PAUSE functions are
selected after Auto-Negotiation is completed, the AN985B/BX enables the PAUSE function for flow control of full
duplex applications. In this section we will describe how the AN985B/BX implements the PAUSE function.
Data Sheet
28
Rev. 1.51, 2005-11-30
INFINEON [ Infineon ]
