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DP83815 View Datasheet(PDF) - National ->Texas Instruments

Part NameDP83815 National-Semiconductor
National ->Texas Instruments National-Semiconductor
Description10/100 Mb/s Integrated PCI Ethernet Media Access Controller and Physical Layer (MacPhyter™)
DP83815 Datasheet PDF : 108 Pages
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3.0 Functional Description (Continued)
3.6 Half Duplex vs. Full Duplex
The DP83815 supports both half and full duplex operation
at both 10 Mb/s and 100 Mb/s speeds.
Half-duplex is the standard, traditional mode of operation
which relies on the CSMA/CD protocol to handle collisions
and network access. In Half-Duplex mode, CRS responds
to both transmit and receive activity in order to maintain
compliance with IEEE 802.3 specification.
Since the DP83815 is designed to support simultaneous
transmit and receive activity it is capable of supporting full-
duplex switched applications with a throughput of up to 200
Mb/s per port when operating in 100BASE-TX mode.
Because the CSMA/CD protocol does not apply to full-
duplex operation, the DP83815 disables its own internal
collision sensing and reporting functions.
It is important to understand that while full Auto-Negotiation
with the use of Fast Link Pulse code words can interpret
and configure to support full-duplex, parallel detection can
not recognize the difference between full and half-duplex
from a fixed 10 Mb/s or 100 Mb/s link partner over twisted
pair. Therefore, as specified in 802.3u, if a far-end link
partner is transmitting forced full duplex 100BASE-TX for
example, the parallel detection state machine in the
receiving station would be unable to detect the full duplex
capability of the far-end link partner and would negotiate to
a half duplex 100BASE-TX configuration (same scenario
for 10 Mb/s).
For full duplex operation, the following register bits must
also be set:
— TXCFG:CSI (Carrier Sense Ignore)
— TXCFG:HBI (HeartBeat Ignore)
— RXCFG:ATX (Accept Transmit Packets)
Additionally, the Auto-Negotiation Select bits in the
Configuration register must show full duplex support:
— CFG:ANEG_SEL
3.7 Phy Loopback
The DP83815 includes a Phy Loopback Test mode for
easy board diagnostics. The Loopback mode is selected
through bit 14 (Loopback) of the Basic Mode Control
Register (BMCR). Writing 1 to this bit enables transmit data
to be routed to the receive path early in the physical layer
cell. Loopback status may be checked in bit 3 of the PHY
Status Register (C0h). While in Loopback mode the data
will not be transmitted onto the media. This is true for either
10 Mb/s as well as 100 Mb/s data.
In 100BASE-TX Loopback mode the data is routed through
the PCS and PMA layers into the PMD sublayer before it is
looped back. Therefore, in addition to serving as a board
diagnostic, this mode serves as quick functional verification
of the device.
Note: A Mac Loopback can be performed via setting bit 29
(Mac Loopback) in the Tx Configuration Register.
3.8 Status Information
There are 3 pins that are available to convey status
information to the user through LEDs to indicate the speed
(10 Mb/s or 100 Mb/s) link status and receive or transmit
activity.
10 Mb/s Link is established as a result of the reception of at
least seven consecutive Normal Link Pulses or the
reception of a valid 10BASE-T packet. LED10N will de-
assert in accordance with the Link Loss Timer specified in
IEEE 802.3.
100BASE-T Link is established as a result of an input
receive amplitude compliant with TP-PMD specifications
which will result in internal generation of Signal Detect.
LED100N will assert after the internal Signal Detect has
remained asserted for a minimum of 500 µs. LED100N will
de-assert immediately following the de-assertion of the
internal Signal Detect.
Activity LED status indicates Receive or Transmit activity.
3.9 100BASE-TX TRANSMITTER
The 100BASE-TX transmitter consists of several functional
blocks which convert synchronous 4-bit nibble data, to a
scrambled MLT-3 125 Mb/s serial data stream. Because
the 100BASE-TX TP-PMD is integrated, the differential
output pins, TD±, can be directly routed to the magnetics.
The block diagram in Figure 3-6 provides an overview of
each functional block within the 100BASE-TX transmit
section.
The Transmitter section consists of the following functional
blocks:
— Code-group Encoder and Injection block (bypass option)
— Scrambler block (bypass option)
— NRZ to NRZI encoder block
— Binary to MLT-3 converter / Common Driver
The bypass option for the functional blocks within the
100BASE-TX transmitter provides flexibility for applications
such as 100 Mb/s repeaters where data conversion is not
always required. The DP83815 implements the 100BASE-
TX transmit state machine diagram as specified in the
IEEE 802.3u Standard, Clause 24.
20
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General Description
DP83815 is a single-chip 10/100 Mb/s Ethernet Controller for the PCI bus. It is targeted at low-cost, high volume PC mother boards, adapter cards, and embedded systems. The DP83815 fully implements the V2.2 33 MHz PCI bus interface for host communications with power management support. Packet descriptors and data are transferred via bus-mastering, reducing the burden on the host CPU. The DP83815 can support full duplex 10/100 Mb/s transmission and reception, with minimum interframe gap.
The DP83815 device is an integration of an enhanced version of the National Semiconductor PCI MAC/BIU (Media Access Controller/Bus Interface Unit) and a 3.3V CMOS physical layer interface.

Features
— IEEE 802.3 Compliant, PCI V2.2 MAC/BIU supports traditional data rates of 10 Mb/s Ethernet and 100 Mb/s Fast Ethernet (via internal phy)
— Bus master - burst sizes of up to 128 dwords (512 bytes)
— BIU compliant with PC 97 and PC 98 Hardware Design Guides, PC 99 Hardware Design Guide draft, ACPI v1.0, PCI Power Management Specification v1.1, OnNow Device Class Power Management Reference Specification - Network Device Class v1.0a
— Wake on LAN (WOL) support compliant with PC98,
PC99, SecureOn, and OnNow, including directed
packets, Magic Packet, VLAN packets, ARP packets,
pattern match packets, and Phy status change
— Clkrun function for PCI Mobile Design Guide
— Virtual LAN (VLAN) and long frame support
— Support for IEEE 802.3x Full duplex flow control
— Extremely flexible Rx packet filtration including: single address perfect filter with MSb masking, broadcast, 512 entry multicast/unicast hash table, deep packet pattern matching for up to 4 unique patterns
— Statistics gathered for support of RFC 1213 (MIB II),
RFC 1398 (Ether-like MIB), IEEE 802.3 LME, reducing
CPU overhead for management
— Internal 2 KB Transmit and 2 KB Receive data FIFOs
— Serial EEPROM port with auto-load of configuration data from EEPROM at power-on
— Flash/PROM interface for remote boot support
— Fully integrated IEEE 802.3/802.3u 3.3V CMOS physical layer
— IEEE 802.3 10BASE-T transceiver with integrated filters
— IEEE 802.3u 100BASE-TX transceiver
— Fully integrated ANSI X3.263 compliant TP-PMD physical sublayer with adaptive equalization and Baseline Wander compensation
— IEEE 802.3u Auto-Negotiation - advertised features configurable via EEPROM
— Full Duplex support for 10 and 100 Mb/s data rates
— Single 25 MHz reference clock
— 144-pin LQFP and 160-pin LBGA packages
— Low power 3.3V CMOS design with typical consumption of 561 mW operating, 380 mW during WOL mode, 33 mW sleep mode
— IEEE 802.3u MII for connecting alternative external Physical Layer Devices

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