DP83955AV National Semiconductor, DP83955AV Datasheet - Page 20

• Manufacturer Part Number: DP83955AV
• Description: IC CTRLR RIC REPEATER 100-PQFP
• Manufacturer: National Semiconductor
• Series: LERIC™r

Specifications of DP83955AV

• Controller Type: LitE Repeater Interface Controller
• Voltage - Supply: 5V
• Current - Supply: 250mA
• Mounting Type: Surface Mount
• Package / Case: 84-LCC (J-Lead)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Operating Temperature: -
• Interface: -
• Other names: *DP83955AV

4-1 and it performs the majority of the data and collision
5 0 Functional Description
Port State Machine (PSM)
There are two primary functions for the PSM as follows
1 Control the transmission of repeated data and jam sig-
2 Decide whether a port will be the source of data or colli-
Main State Machine (MSM)
The MSM controls the operation of the shared functional
blocks in each LERIC as shown in the block diagram Figure
propagation operations as defined by the IEEE specifica-
tion these include those shown in Table 5-1
The interaction of the main and port state machines is visi-
ble in part by observing the Inter-LERIC bus
Regeneration
Enforcement
Enforcement
Enforcement
Generation
COLLISION state a further arbitration operation is per-
PORT M does not transmit to its segment where as all
nals over the attached segment
sion information which will be repeated over the network
This repeater port is known as PORT N An arbitration
process is required to enable the repeater to transition
from the IDLE state to the SEND PREAMBLE PATTERN
or RECEIVE COLLISION states see Figure 5-2 This pro-
cess is used to locate the port which will be PORT N for
that particular packet The data received from this port is
directed to the PLL decoder and transmitted over the
Inter-LERIC bus If the repeater enters the TRANSMIT
formed to determine which port is PORT M PORT M is
differentiated from the repeater’s other ports if the re-
peater enters the ONE PORT LEFT state In this state
other ports are still required to transmit to their seg-
ments
Extension
Function
Preamble
Fragment
Preamble
Encoding
Elasticity
Transmit
Collision
Control
Pattern
Control
Buffer
Jam
Data
Tw1
Tw2
TABLE 5-1 Main State Machine Operations
Restore the length of the preamble
pattern to the defined size
Extend received data or collision
fragments to meet the minimum
fragment length of 96 bits
A portion of the received packet may
require storage in an Elasticity Buffer to
accommodate preamble regeneration
In cases of receive or transmit collisions
a LERIC is required to transmit a jam
pattern (1010
Note This pattern is the same as that used for
Once the TRANSMIT COLLISION state
is entered a repeater is required to stay
in this state for at least 96 network bit
times
NRZ format data from the elasticity
buffer must be encoded into Manchester
format data prior to retransmission
Enforce the Transmit Recovery Time
specification
Enforce Carrier Recovery Time
specification on all ports with active
collisions
preamble regeneration
Action
)
(Continued)
20
Inter-LERIC Bus Operation
Overview
The Inter-LERIC Bus like the Inter-RIC Bus consists of
eight signals These signals implement a protocol which
may be used to connect multiple LERICs together In this
configuration the logical function of a single repeater is
maintained The resulting multi-LERIC system is compliant
to the IEEE 802 3 Repeater Specification and may connect
several hundred network segments An example of a multi-
LERIC system is shown in Figure 5-3
The Inter-LERIC Bus connects multiple LERICs to realize
the following operations
The following tables briefly describe the operation of each
bus signal the conditions required for a LERIC to assert a
signal and which LERICs (in a multi-LERIC system) would
monitor a signal
Note 1 This input is tied at a logic high state
Port N Identification (which port the repeater receives
Port M Identification (which port is the last one experi-
RECEIVE COLLISION identification
TRANSMIT COLLISION identification
DISABLE OUTPUT (jabber protection)
data from)
encing a collision)
Data Transfer
FIGURE 5-3 LERIC System Topology
TL F 11240 – 9