
184
Am79C978
HPR20 and HPR21: HomePNA PHY RxCOMM
(Registers 20 and 21)
Table 53.
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
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 HPR26). Accessing
the high word of the register clears this bit and allows
over-writing of the register by subsequent received
packets.
HPR22: HomePNA PHY AID (Register 22)
Table 54.
HPR22: HomePNA PHY AID (Register 22)
The PHY
’
s AID address is used for collision detection.
Unless bit 7 of the CONTROL register is set, the PHY
is assured to select a unique AID address. Addresses
above EFh are reserved. Address FFh is defined to in-
dicate a remote command.
HPR23: HomePNA PHY Noise Control (Register 23)
Table 55.
HPR23: HomePNA PHY Noise Control (Register 23)
Hex
Mnemonic
Description
Read/
Write
Default
Hex
Soft
Reset
14-15
PHY_RX_COMM (4)
The 32-bit preamble received on the
HomePNA PHY. Register 14 contains the high
word and Register 15 the low word.
R
All 0s
All 0s
Bits
Mnemonic
Description
Read/
Write
Default
Hex
Soft
Reset
PHY_AID
15:8
PHY_AID
The Address ID of this PHY
If PHY_Control Disable AID Negotiation is not
set then writes to this bit will have no effect.
R/W
00
00
7:0
Noise Events
An 8-bit counter that records the number of
noise events detected. Overflows are held as
FFh. Can be cleared by setting bit 6 of the
control register.
R/W
00
00
Bits
Mnemonic
Description
Read/
Write
Default
Hex
Soft
Reset
PHY_NOISE_CTRL1
15:8
Noise Floor
The minimum value of the NOISE
measurement.
R/W
03
03
7:0
Noise Ceiling
The maximum value if the NOISE
measurement. If it is exceeded, NOISE is reset
to the FLOOR.
R/W
FF
FF