AM79C978A AMD [Advanced Micro Devices], AM79C978A Datasheet - Page 80

• Manufacturer Part Number: AM79C978A
• Description: Single-Chip 1/10 Mbps PCI Home Networking Controller
• Manufacturer: AMD [Advanced Micro Devices]

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
2. A slave is identified with an AID of 00h to EFh.
3. AID values of F0h to FEh are reserved for future
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
2. SET_SPEED: Commands slave stations to set their
The control word bit encoding and possible values are de-
scribed in Table 16.
80
Table 16. Master Station Control Word Functions
Bit No.
wire network with an AID of FFh.
use.
their transmit level to a prescribed level.
transmit speed to a prescribed value.
0
1
2
3
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
Command Function
Am79C978A
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
2. POWER_STATUS: The transmit power level of the
3. SPEED_STATUS: The transmit speed of the slave
The slave control word bit encoding and possible values
are described in Table 17.
PHY Control and Management Block
(PCM Block)
Register Administration for 10BASE-T PHY Device
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 #
Table 17. Slave Station Control Word Status
of the slave station.
transmitting slave station for the current frame. All
HomePNA units suppor t LOW_POWER and
HIGH_POWER modes.
station for the current frame. Receiving stations will
adjust their receiver parameters to correctly inter-
pret this frame.
0
1
2
3
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
Conditions
Indicated Status