DM9801
1M Home Phoneline Network Physical Layer Single Chip Transceiver
General Purpose Serial Interface
16
Preliminary
Version: DM9801-DS-P02
March 20, 2000
The DM 9801 provides a subset Media Independent
Interface (MII) or a pseudo-standard General Purpose
Serial Interface (GPSI). The GPSI interface provides a
simple, easy way to implement connection between the
MAC Reconciliation layer and the DM9801 transceiver.
The GPSI is designed to make the differences between
various media transparent to the MAC sublayer.
The GPSI interface provides a serial receive data bus, a
serial transmit data bus, and control signals to facilitate
data transfers between the DM9801 transceiver and the
Reconciliation layer. The seven signals which comprise
the GPSI are STXDAT, STDCLK, STXEN, SRXDAT,
SRXCLK, CLSN, and CRS. Of these, only STXEN and
STXDAT are inputs to the DM9801, the other five are
outputs from the DM9801.
STXDAT (serial transmit data) is a serial stream of data
that are driven by the reconciliation sublayer
synchronously with respect to STDCLK. For each
STDCLK period, which STXEN is asserted, STXDAT is
accepted for transmission by the PHY.
STDCLK (serial transmit data clock) is an output to the
MAC reconciliation sublayer. STDCLK is a clock that
provides the timing reference for the transfer of the
STXDAT in GPSI mode.
STXEN (serial transmit enable) input from the MAC
reconciliation sublayer to indicate serial data is being
presented on the GPSI for transmission on the physical
medium.
SRXDAT (serial receive data) is a serial stream of data
that is sampled by the reconciliation sublayer
synchronously with respect to SRXCLK.
SRXCLK (serial receive data clock) is an output to the
MAC reconciliation sublayer. SRDCLK is a clock that
provides the timing reference for the transfer of the
SRXDAT in GPSI mode.
CLSN (collision detect) is an output to the MAC
reconciliation sublayer. CLSN is asserted high to
indicate detection of collision condition
CRS (carrier sense) is an output to the MAC reconciliation
sublayer that is asserted high to indicate the
presence of carrier due to receive or transmit
activities.
The subsequent sections analyze each GPSI related state
of the DM9801 in detail.
STDCLK
SRDCLK
STXEN
STXDAT
CRS
SRXDAT
CLSN
SRDCLK and STDCLK are synchronized. All other signals are inactive.
Idle State
Figure 11