AM79C978AVCW datasheet(80/256 Pages) AMD

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Am79C978A

Header AID Remote Control Word Commands

Stations may be configured either as master stations or

as slave stations. Only one master may exist on a given

HomePNA segment.

The master station may send commands embedded in

the HomePNA header control word to remotely set vari-

ous parameters of the remote slave stations. Stations are

identified via the AID as follows:

1. The master station is identified on the HomePNA

wire network with an AID of FFh.

2. A slave is identified with an AID of 00h to EFh.

3. AID values of F0h to FEh are reserved for future

use.

Once a command has been transmitted, the master sta-

tion will revert to a slave AID, so that subsequent control

words are not interpreted as new commands.

Master mode is entered by writing to the PHY control reg-

ister (HPR16) and is exited upon the completion of the

command sequence.

A valid master remote command consists of three Home-

PNA frames with an AID of FFh. Since the HomePNA

header is prepended to packets received from the MAC,

packets from the master station may be separated by in-

tervals during which other (slave) stations may transmit

their frames.

A remote master Control Word command must be recog-

nized and executed by a HomePNA PHY when it re-

ceives three consecutive valid HomePNA frames with an

AID of FFh.

If HPR16, bit 15 is not set to 0, valid commands are as fol-

lows:

1. SET_POWER: Commands slave stations to set

their transmit level to a prescribed level.

2. SET_SPEED: Commands slave stations to set their

transmit speed to a prescribed value.

The control word bit encoding and possible values are de-

scribed in Table 16.

Table 16.

Master Station Control Word Functions

All stations will transmit the following status messages in

the HomePNA header control word of all outgoing

frames:

1. VERSION_STATUS: The HomePNA PHY version

of the slave station.

2. POWER_STATUS: The transmit power level of the

transmitting slave station for the current frame. All

HomePNA units suppor t LOW_POWER and

HIGH_POWER modes.

3. SPEED_STATUS: The transmit speed of the slave

station for the current frame. Receiving stations will

adjust their receiver parameters to correctly inter-

pret this frame.

The slave control word bit encoding and possible values

are described in Table 17.

Table 17.

Slave Station Control Word Status

Conditions

PHY Control and Management Block

(PCM Block)

The management interface specified in Clause 22 of the

IEEE 802.3u standard provides for a simple two wire, se-

rial interface to connect a management entity and a man-

aged PHY for the purpose of controlling the PHY and

gathering status information. The two lines are Manage-

ment Data Input/Output (MDIO) and Management Data

Clock (MDC). A station management entity which is at-

tached to multiple PHY entities must have prior knowl-

edge of the appropriate PHY address for each PHY entity.

Description of the Methodology

The management interface physically transports man-

agement information across the internal MII. The informa-

tion is encapsulated in a frame format as specified in

Clause 22 of the IEEE 802.3u draft standard and is shown

in Table 18.

Bit No.

Command Function

0 = version 0 (All stations revert to version 0

HomePNA PHY mode of operation).

0 = Set transmit to low speed.

1 = Set transmit to high speed.

0 = Set to low power transmit mode.

1 = Set to high power transmit mode.

Reserved

Bit #

Indicated Status

0 = This station is version 0.

1 = This station is not version 0.

0 = Frame transmitted at low speed.

1 = Frame transmitted at high speed.

0 = Frame transmitted at low power.

1 = Frame transmitted at high power.

Reserved

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