Table 14. Master Station Control Word Functions
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.
Aid No.
LSB
MSB
Set to:
5
Version
0 = Low Power
1 = High Power
The master station may send commands embedded in
the HomePNA header control word to remotely set var-
ious parameters of the remote slave stations. Stations
are identified via the AID as follows:
Set to:
6
0 = Low Speed
1 = High Speed
Reserved
1. The master station is identified on the HomePNA
wire network with an AID of FFh.
All stations will transmit the following status messages
in the HomePNA header control word of all outgoing
frames:
2. A slave is identified with an AID of 00h to EFh.
3. AID values of F0h to FEh are reserved for future
use.
1. VERSION_STATUS: The HomePNA PHY version
of the slave station.
Once a command has been transmitted, the master
station will revert to a slave AID, so that subsequent
control words are not interpreted as new commands.
2. POWER_STATUS: The transmit power level of the
transmitting slave station for the current frame. All
HomePNA units support LOW_POWER and
HIGH_POWER modes.
Master mode is entered by writing to the PHY control
register (HPR16) and is exited upon the completion of
the command sequence.
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.
A valid master remote command consists of three
HomePNA frames with an AID of FFh. Since the
HomePNA header is prepended to packets received
from the MAC as well as Any1Home packets. Packets
from the master station may be separated by intervals
during which other (slave) stations may transmit their
frames.
The slave control word bit encoding and possible val-
ues are also described in Table 14.
PHY Control and Management Block (PCM
Block)
A remote master Control Word command must be rec-
ognized and executed by a HomePNA PHY when it re-
ceives three consecutive valid HomePNA frames with
an AID of FFh.
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, serial interface to connect a management entity
and a managed PHY for the purpose of controlling the
PHY and gathering status information. The two lines
are Management Data Input/Output (MDIO) and Man-
agement Data Clock (MDC). A station management
entity which is attached to multiple PHY entities must
have prior knowledge of the appropriate PHY address
for each PHY entity.
If HPR16, bit 15 is not set to 0, valid commands are as
follows:
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
described in Table 14.
Description of the Methodology
The management interface physically transports man-
agement information across the internal and external
MII. The information is encapsulated in a frame format
as specified in Clause 22 of the IEEE 802.3u draft stan-
dard and is shown in Table 15.
Table 15. MII Control Frame Format
OP PHYAD REGAD
AAAAA RRRRR
AAAAA RRRRR
PRE
1.1
ST
01
01
TA
Z0
10
DATA
IDLE
READ
10
01
D31………D0
D31………D0
Z
Z
WRITE
1.1
Am79C978
81
AMD [ AMD ]
