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The 8B/10B encoder converts 8-bit wide data to a 10-bit wide encoded data character to improve its
transition density. This transmission code includes D Characters, used for transmitting data, and K
Characters, used for transmitting protocol information. Each K or D character code word can also have
both a positive and a negative disparity version. The disparity of a code word is selected by the encoder to
balance the running disparity of the serialized data stream.
The generation of K-characters to be transmitted on each channel is controlled by transmit control pins,
TXC(3:0). When the control pin is asserted along with the 8 bits of data, an 8B/10B K-character is
transmitted. Similarly, reception of K-characters is reported by the receive control pins, RXC(3:0). When
receive control pin is asserted, the corresponding byte on the receive data bus should be interpreted as a
K-character. The TLK3134 will transmit and receive all of the twelve valid K-characters as defined in
Table
2-15.
TXC(3:0)
K-CODE
OR
RXC(3:0)
00 through FF
0
K28.0
1
K28.1
1
K28.2
1
K28.3
1
K28.4
1
K28.5
1
K28.6
1
K28.7
1
K23.7
1
K27.7
1
K29.7
1
K30.7
1
Table 2-16
provides additional transmit data control coding and descriptions that have been incorporated
into 10 Gbps Ethernet. Data patterns put on XGMII transmit data bus other than those defined in
Table 2-16
when the transmit control pin is asserted will result in an invalid K-character being transmitted
which will result in a code error at the receiver.
DATA BUS
(TXD[x: x-7]
OR RXD[x: x-7])
00 through FF
00 through 06
07
08 through 9B
9C
9D through FA
FB
FC
FD
FE
Copyright © 2007–2009, Texas Instruments Incorporated
Table 2-15. Valid K-Codes
DATA BUS BYTES
NEGATIVE
(RXD[x: x-7]
RUNNING
OR TXD[x: x-7])
DISPARITY
DDD DDDDD
dddddd dddd
000 11100
001111 0100
001 11100
001111 1001
010 11100
001111 0101
011 11100
001111 0011
100 11100
001111 0010
101 11100
001111 1010
110 11100
001111 0110
111 11100
001111 1000
111 10111
111010 1000
111 11011
110110 1000
111 11101
101110 1000
111 11110
011110 1000
Table 2-16. Valid XGMII Channel Encodings
TXC(3:0)
OR
RXC(3:0)
0
Normal Data Transmission
1
Reserved
1
Idle
1
Reserved
1
Sequence (only valid in Channel 0)
1
Reserved
1
Start (only valid in Channel 0)
1
Reserved
1
Terminate
1
Transmit error propagation
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Product Folder Link(s):
SLLS838F – MAY 2007 – REVISED DECEMBER 2009
ENCODED K-CODE
POSITIVE
RUNNING
DISPARITY
dddddd dddd
110000 1011
110000 0110
110000 1010
110000 1100
110000 1101
110000 0101
110000 1001
110000 0111
000101 0111
001001 0111
010001 0111
100001 0111
DESCRIPTION
TLK3134
TLK3134
K-CODE DESCRIPTION
Normal data
IdleO/busy
IdleE/busy
Channel Alignment (A)
IdleE/not-busy (K)
Code Violation or Parity Error
IdleO/not-busy
SOP(S)
EOP(T)
Detailed Description
35
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