AM79C978A AMD [Advanced Micro Devices], AM79C978A Datasheet - Page 191

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

HPR18 and HPR19: HomePNA PHY TxCOMM
(Registers 18 and 19)
The 32-bit transmitted data field is to be used for out-
of-band communication between PHY management
entities. No protocol for out-of-band management has
been defined. Accessing the low word causes the PHY
to send all-0 PCOMs until the high word has been ac-
cessed. Once accessed, the next transmitted packet
will cause this register’s contents to be shifted out in
HPR20 and HPR21: HomePNA PHY RxCOMM
(Registers 20 and 21)
The 32-bit received data field to be used for out-of-
band communication between PHY management enti-
ties. No protocol for out-of-band management has
been defined. Accessing the low word of the register is
sufficient to ensure that subsequently received packets
12-13
14-15
Hex
Hex
Address
Address
Bits
Bits
Table 67. HPR20 and HPR21: HomePNA PHY RxCOMM (Registers 20 and 21)
Table 66. HPR18 and HPR19: HomePNA PHY TxCOMM (Registers 18 and 19)
PHY_TX_COMM (4)
PHY_RX_COMM (4)
Mnemonic
Mnemonic
The 32-bit preamble transmitted on the
HomePNA PHY. Register 12 contains the
high word and Register 13 the low word.
The 32-bit preamble received on the
HomePNA PHY. Register 14 contains the
high word and Register 15 the low word.
Am79C978A
Description
Description
the PCOM field of the transmitted packet. Upon trans-
mission, this register will read back as all 0s. A non-null
transmitted PCOM will set the TxPCOM Ready bit in
the Event Status Register (Register 1A). An access to
any of the two TxPCOM words will clear the TxPCOM
Ready bit in the ISTAT register.
will not over-write the register contents. A non-null re-
ceived PCOM will set the RxPCOM Valid bit of the
Event Status Register (Register 1A). Accessing the
high word of the register clears this bit and allows over-
writing of the register by subsequent received packets.
Read/
Read/
Write
Write
R/W
R
Default
Default
All 0s
All 0s
Hex
Hex
Reset
Reset
All 0s
All 0s
Soft
Soft
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