AM79C901AJCT AMD [Advanced Micro Devices], AM79C901AJCT Datasheet - Page 37

• Manufacturer Part Number: AM79C901AJCT
• Description: HomePHY Single-Chip 1/10 Mbps Home Networking PHY
• 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 or network over which the
HomePNA PHY header is preserved.
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:
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 use.
Once a command has been transmitted, the master
station will revert to a slave AID, so that subsequent
control words are not interpreted by the slave stations
as new commands.
Master mode is entered by writing to the PHY control
register (HPR16, bits 8 to 11) and is exited upon the
completion of the command sequence.
A valid master remote command consists of three
HomePNA frames with an AID of FFh. Since the
HomePNA PHY header is prepended to packets re-
ceived 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.
A remote master Control Word command will be recog-
nized and executed by a HomePNA PHY when it re-
ceives three consecutive valid HomePNA frames with
an AID of FFh.
Valid commands are as follows:
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
described in Table 9.
wire network with an AID of FFh.
their transmit level to a prescribed level until another
master command is received.
transmit speed to a prescribed value until another
master command is received.
P R E L I M I N A R Y
Am79C901A
Slave stations transmit the following status messages
in the HomePNA header control word of all outgoing
frames:
1. VERSION_STATUS: The HomePNA PHY version of
2. POWER_STATUS: The transmit power level of the
3. SPEED_STATUS: The transmit speed of the slave
The slave control word bit encoding is identical to the
master control word format.
1 Mbps HomePNA PHY Loopback
The HomePNA PHY is capable of supporting internal
loopback only.
Internal Loopback
In internal loopback, the transmitted data is returned to
the receive data bus without transmitting data on the
network. The MAC must be programmed to support
full-duplex operation and is responsible for comparing
the transmitted data to that received. Internal loopback
is accomplished by setting the “enable loopback mode”
in HPR0, bit 14, to 1.
any1Home Link Detection
While consuming minimal network resources, AMD’s
innovative any1Home Link Detection Packet provides a
means to indicate to the MAC, and thus the upper lay-
ers of the system protocol, that a valid network (as de-
fined by HomePNA) has been detected. The Link
Detection Packet is also capable of detecting a network
failure and allows the upper layer protocol to take cor-
rective action. Thus, the any1Home Packet provides
link indication that the MAC requires for compliance to
the Microsoft PC98, PC99, and HomePNA revision 1.1
requirements without utilizing resources from the upper
layers of the system protocol
Table 9. Master Station Control Word Functions
AID
the slave station. The receiving station must revert to
this version to interpret the packet.
transmitting slave station for the current frame. All
HomePNA units support both LOW_POWER and
HIGH_POWER modes of operation.
station for the current frame. Receiving stations will
adjust their receiver parameters to correctly interpret
this frame.
5
5
6
6
Bit No.
MSB
MSB
LSB
LSB
0 = version 0
0 = Set to low-power transmit mode.
1 = Set to high-power transmit mode.
0 = Set to low-speed transmit mode.
1 = Set to high-speed transmit mode.
Reserved
Command Function
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