dp83251 National Semiconductor Corporation, dp83251 Datasheet - Page 4

• Manufacturer Part Number: dp83251
• Description: Player Device Fddi Physical Layer Controller
• Manufacturer: National Semiconductor Corporation

2 0 Architecture Description
2 1 OVERVIEW
The PLAYER device is comprised of four blocks Receiver
Transmitter Configuration Switch and Control Bus Interface
as shown in Figure 2-1
Receiver
During normal operation the Receiver Block accepts serial
data as inputs at the rate of 125 Mbps from the Clock Re-
covery Device (DP83231) During the Internal Loopback
mode of operation the Receiver Block accepts data from
the Transmitter Block as inputs
The Receiver Block performs the following operations
Finally the Receiver Block presents data symbol pairs
(bytes) to the Configuration Switch Block
Configuration Switch
An FDDI station may be in one of three configurations Iso-
late Wrap or Thru The Configuration Switch supports these
configurations by switching the transmitted and received
data paths between the PLAYER and BMAC devices
The configuration switching is performed internally there-
fore no external logic is required for this function
Transmitter
The Transmiter Block accepts 10-bit bytes from the Config-
uration Switch
The Transmitter Block performs the following operations








Converts the incoming data stream from NRZI to NRZ if
necessary
Decodes the data from 5B to 4B coding
Converts the serial bit stream into 10-bit bytes
Compensates for the differences between the upstream
and local clocks
Decodes Line States
Detects link errors
Encodes the data from 4B to 5B coding
Filters out code violations from the data stream
FIGURE 2-1 PLAYER Device Block Diagram
4
During normal operation the Transmitter Block presents se-
rial data to the fiber optic transmitter While in the External
Loopback mode the Transmitter Block presents serial data
to the Clock Recovery Device
Control Bus Interface
The Control Bus Interface allows a user to
The Control Bus Interface also performs the following func-
tions
2 2 INTERFACES
The PLAYER device connects to external components via 5
functional interfaces Serial Interface PHY Port Interface
Control Bus Interface Clock Interface and the Miscellane-
ous Interface
Serial Interface
The Serial Interface connects the PLAYER device to a fiber
optic transmitter (FOTX) and the Clock Recovery Device
(DP83231)








Generates Idle Master Halt Quiet or other user defined
symbol pairs upon request
Converts the data stream from NRZ to NRZI format
ready for transmission if necessary
Provides smoothing function when necessary
Program the Configuration Switch
Enable disable functions within the Transmitter and Re-
ceiver Blocks (i e NRZ NRZI Encoder Smoother PHY
Request Data Parity Line State Generation Symbol Pair
Injection NRZ NRZI Decoder Cascade Mode etc )
Monitors Line States received
Monitors link errors detected by the Receiver Block
Monitors other error conditions
TL F 10386 – 2