CN7221 Datasheet, PDF (10/18 Pages) Conexant Systems, Inc – Home Networking Physical Layer Device with Integrated Analog Front End Circuitry

LANfinity™ CN7221
LANfinity RS7112 Interface
The RS7112 interface consists of the SPI signals (see page
9), and the HLAN_IRQ# signal.
All SPI registers in the system are readable and writable.
The TxSPEED, TxPOWER, and CMDignore bits of the
CONTROL register may be set or cleared in two ways: SPI
CONTROL register write or remote management command
(TxSPEED and TxPOWER only). These methods may
overwrite one another. After reset, any change in the state
of those pins will update the CONTROL register bits.
Signal
HLAN_IRQ#
Table 5. RS7112 Interface Signals
Description
Active low processor interrupt
Home Networking PHY with Integrated AFE
Remote Commands
Any node in a home phoneline network may issue remote
commands. The effect of a remote command is to set the
transmit speed and power of all nodes in the network. A
remote command is encoded in the AID header and is
identified by having an AID address of 0xFF. The remaining
AID header information contains the commanded power
and speed. Three identical remote commands must be
received before a PHY will respond by changing its’
transmit speed and power. Once three identical remote
commands have been received, however, the transmit
speed and power are updated and bit 1 of the ISTAT
register is set.
The PHY will issue three remote commands when any one
of bits 8 through 11 of the CONTROL register is set. As
soon as these bits are set, the PHY will automatically
update it’s own transmit speed and power and start issuing
the remote command on subsequent packets until three
packets have been successfully transmitted (that is,
without collision). Once the three remote commands have
been sent, bits 8 through 11 of the CONTROL register will
be cleared and bit 0 of the ISTAT register will be set.
10
Conexant
LAN-056, Rev. A
PROPRIETARY INFORMATION