DM9801
1M Home Phoneline Network Physical Layer Single Chip Transceiver
10
Preliminary
Version: DM9801-DS-P02
March 20, 2000
Functional Description
The DM9801 is a single-chip Home Phoneline Network
transceiver .The DM9801 provides an IEEE 802.3u
subset Media Independent Interface (MII) or a pseudo-
standard General Purpose Serial Interface (GPSI).
The DM9801 enables home networking by allowing
Ethernet packets to be transported over common home
telephone wiring with no modifications, using Ethernet
CSMA/CD media access control procedures as defined in
the IEEE 802.3 standard. Figure 1 shows the major
functional blocks implemented in the DM9801.
Figure 1
MII Interface
The DM9801 provides a subset Media Independent
Interface (MII) or a pseudo-standard General Purpose
Serial Interface (GPSI). The MII interface provides a
simple, easy way to implement connection between the
MAC Reconciliation layer and the DM9801 transceiver.
The MII is designed to make the differences between
various media transparent to the MAC sublayer.
The MII consists of a nibble wide receive data bus, a
nibble wide transmit data bus, and control signals to
facilitate data transfers between the PHY and the
Reconciliation layer.
TXD (transmit data) is a nibble (4 bits) of data that are
driven by the reconciliation sublayer synchronously with
respect to TX_CLK. For each TX_CLK period, which
TX_EN is asserted, TXD (3:0) are accepted for
transmission by the PHY.
TX_CLK (transmit clock) output to the MAC reconciliation
sublayer is a clock that provides the timing reference for
the transfer of the TX_EN, TXD, and TX_ER signals.
TX_EN (transmit enable) input from the MAC
reconciliation sublayer to indicate nibbles are being
presented on the MII for transmission on the physical
medium.
Muxed
GPSI or MII
Interface
RLL25
Encoder
RLL25
Decoder
Master PHY
Controller
Receiver
and
Digital PLL
Receiver AFE
HN Drivers
Transmit
Timing
Generator
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