8B10B Datasheet, PDF (1/12 Pages) Altera Corporation – Encoder/Decoder

v2.0
8b10b Macro
Product Summary
• Gigabit Ethernet 8b10b Function
• 125 MHz Operation
• Transmit and Receive Function
• Disparity and Illegal Code Error Checking
• Connects directly to industry-standard Gigabit Ethernet
Transceiver devices.
• Supports either single or dual channel transceiver in a
single device.
Version
This data sheet defines the functionality of Version 1.0 of the
8b10b macro.
General Description
The 8b10b macro implements the function for the physical
coding sublayer for Gigabit Ethernet as defined in the IEEE
802.3z specification. The 8b10b is a marriage of two
sub-blocks, the 5b6b and the 3b4b encoder/decoders
(ENDECs). The purpose of the ENDEC is to convert 8-bit data
into a 10-bit code that contains an equal number of 0’s and
1’s. In addition, the code is built so that no more than five
consecutive 0’s or 1’s are ever transmitted. The 8b10b macro
is designed to work with a variety of standard transceiver
devices. A set of generic signals provides a data and command
interface with the system logic. A system-level block diagram
describing the use of the 8b10b macro is shown in Figure 1.
The 8b10b macro provides a user interface and a transceiver
interface. The user interface consists of transmit data,
receive data, and several control and status signals used to
qualify the data. To simplify the timing of the user interface,
the data transmission is word-wide (16-bits) and operates at
62.5 MHz. This strategy provides a simplified timing interface
for system logic yet still meets the 125 megabyte per second
requirements for Gigabit Ethernet.
The transceiver interface is designed to connect directly to
most commercially-available Gigabit Ethernet transceiver
devices. The transceiver is responsible for serializing
transmit data and deserializing receive data. In addition, the
receiver is designed to resynchronize the serial stream
whenever an external device detects illegal coding errors.
TX_WORD[15:0]
TX_K_CHAR[1:0]
TX_WRn
INVALID_K
CLK125
RSTn
RX_WORD[15:0]
RX_K_CHAR[1:0]
CODE_ERRORn[1:0]
WORD_SYNCn
RX_CLK
8b10b Macro
Transmitter
TX_DATA[9:0]
TRANSCEIVER
SERIAL_TX
Receiver
RX_DATA[9:0]
COMMA_DETECT
RBC0
RBC1
COMMA_DET_EN
SERIAL_RX
Figure 1 • System Block Diagram Depicting 8b10b Macro Usage
May 2000
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© 2000 Actel Corporation