STE10 datasheet(52/66 Pages) STMICROELECTRONICS

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STE10/100

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(FLPs) - a burst of link pulses. There are 16 bits of signaling information contained in the link pulses

which advertise to the remote partner the capabilities which are represented by the contents of ANA

(register XR4). According to this information the partners find out their highest common capabilities by

following the priority sequence listed 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 enabled, the FLPs will be transmitted and the Auto-Negotia-

tion function will proceed. Otherwise, Auto-Negotiation will not occur until ANEN (bit 12 of XR0) is set to 1.

When the Auto-Negotiation is disabled, then Network Speed and Duplex Mode are selected by programming

the XR0 register.

Power Down Operation

The transceiver is designed with a power-down feature which can reduce power consumption

significantly. Since the power supply of the 100BASE-TX and 10BASE-T circuits are separate, the

transceiver can turn off the circuit of either the 100BASE-TX or 10BASE-T when the other is active.

6.5.3 Flow Control in Full Duplex Application

The PAUSE function is used to inhibit transmission of data frames for a specified period of time. The STE10/

100 supports the full duplex protocol of IEEE802.3x. To support the PAUSE function, the STE10/100 imple-

ments the MAC Control Sub-layer functions to decode the MAC Control frames received from MAC control cli-

ents and to execute the relative requests accordingly. When Full Duplex mode and the PAUSE function are

selected after Auto-Negotiation completes (refer to the configuration of XR8), the STE10/100 will enable the

PAUSE function for flow control in a full duplex application. In this section we will describe how the STE10/100

implements the PAUSE function.

MAC Control Frame and PAUSE Frame

Figure 14. MAC Control Frame Format

The MAC Control frame is distinguished from other MAC frames only by its Length/Type field identifier. The

MAC Control Opcode defined in MAC Control Frame format for th PAUSE function is 0001h, and the PAUSE

time is specified in the MAC Control Parameters field with 2 Octets, representing an unsigned integer, in units

of Slot-Times. The range of possible PAUSE times is 0 to 65535 Slot-Times.

A valid PAUSE frame issued by a MAC control client (e.g., a switch or a bridge) would contain:

The destination address, set to the globally assigned 48 bit mulitcast address 01-80-C2-00-00-01,

or to the unicast address to which the MAC control client requests to inhibit its transmission of data

frames.

The MAC Control Opcode field set to 0001h.

6 Octets

Destination Address

6 Octets

Source Address

2 Octets

Length/Type = 88-08h

2 Octets

MAC Control Opcode

MAC Control Parameter

(minFrameSize - 160) / 8 Octets

Reserved(pads with zeroes)

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