1892Y-14LFT IDT, Integrated Device Technology Inc, 1892Y-14LFT Datasheet - Page 45

• Manufacturer Part Number: 1892Y-14LFT
• Manufacturer: IDT, Integrated Device Technology Inc

Specifications of 1892Y-14LFT

• Lead Free Status / RoHS Status: Compliant

7.3.6 4B/5B Encoding/Decoding
ICS1892, Rev. D, 2/26/01
The 4B/5B coding methodology maps each 4-bit nibble to a 5-bit symbol (also called a “code group”). There
are 32 five-bit symbols, which include the following:
•
•
Note:
Of the 32 five-bit symbols, 16 five-bit symbols are required to represent the 4-bit nibbles.
The remaining 16 five-bit symbols are available for control functions. The IEEE Standard defines 6
symbols for control, and the remaining 10 symbols of this grouping are invalid. The 6 control symbols
include the following:
If the ICS1892 PCS receives:
– /H/ represents a Transmit Error
– /I/ represents an IDLE
– Two symbols represent the Start-of-Stream Delimiter (SSD): /J/ and /K/
– Two symbols represent the End-of-Stream Delimiter (ESD): /T/ and /R/
– One of the 10 undefined symbols, it sets the QuickPoll Detailed Status Register’s Invalid Symbol bit
– A Halt symbol, it sets the Halt Symbol Detected bit in the QuickPoll Detailed Status Register (bit 17.6)
ICS1892
(bit 17.7) to logic one.
to logic one.
By an STA (1) setting the Extended Control Register’s Transmit Invalid Codes bit (bit 16.2) to logic
one and (2) asserting the TXER signal, an STA can force the ICS1892 to transmit symbols that are
typically classified as invalid. For more information, see
16.2)”.
© 2000-2001, Integrated Circuit Systems, Inc.
All rights reserved.
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Section 8.11.7, “Invalid Error Code Test (bit
Chapter 7 Functional Blocks
February 26, 2001