TLK3114SA_13 Datasheet, PDF (25/66 Pages) Texas Instruments – 10-Gbps XAUI Transceiver

Table 3−4. Valid K-Codes
K-CODE
TDX8 OR RDX8
DATA BUS
(RDX[7:0] OR
TDX[7:0])
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
† _{A comma is contained within this K-code.}
dddddddd
000 11100
001 11100
010 11100
011 11100
100 11100
101 11100
110 11100
111 11100
111 10111
111 11011
111 11101
111 11110
ENCODED K-CODE
NEGATIVE
RUNNING
DISPARITY
POSITIVE
RUNNING
DISPARITY
dddddddddd
dddddddddd
001111 0100
110000 1011
001111 1001
110000 0110
001111 0101
110000 1010
001111 0011
110000 1100
001111 0010
110000 1101
001111 1010
110000 0101
001111 0110
110000 1001
001111 1000
110000 0111
111010 1000
000101 0111
110110 1000
001001 0111
101110 1000
010001 0111
011110 1000
100001 0111
K-CODE DESCRIPTION
Normal data
IdleO/busy
IdleE/busy
Channel alignment precursor
IdleE/not busy
Code violation or parity error
IdleO/not busy
SOP(S)
EOP(T)
Table 3−5. Valid XGMII Channel Encodings
DATA BUS
(TDX[7:0]^† OR RDX[7:0]‡)
TDX8§ OR RDX8¶
DESCRIPTION
00 through FF
0
Normal data transmission
00 through 06
1
Reserved
07
1
Idle
08 through 9B
1
Reserved
9C
1
Sequence (only valid in channel A)
9D through FA
1
Reserved
FB
1
Start (only valid in channel A)
FC
1
Reserved
FD
1
Terminate
FE
1
Transmit error propagation
FF
1
Reserved
† _{XGMII names: TDA[7:0] = TXD[7:0], TDB[7:0] = TXD[15:8], TDC[7:0] = TXD[23:16], and TDD[7:0] = TXD[31:24]}
‡ _{XGMII names: RDA[7:0] = RXD[7:0], RDB[7:0] = RXD[15:8], RDC[7:0] = RXD[23:16], and RDD[7:0] = RXD[31:24]}
§ _{XGMII names: TDA8 = TXC0, TDB8 = TXC1, TDC8 = TXC2, and TDD8 = TXC3}
¶ _{XGMII names: RDA8 = RXC0, RDB8 = RXC1, RDC8 = RXC2, and RDD8 = RXC3}
3.12 Comma Detect and 8-b/10-b Decoding
When parallel data is clocked into a parallel-to-serial converter, the byte boundary that was associated with the
parallel data is lost in the serialization of the data. When the serial data is received and converted to parallel format
again, a method is needed to be able to recognize the byte boundary. Generally, this is accomplished through the
use of a synchronization pattern. This is a unique pattern of 1s and 0s that either cannot occur as part of valid data
or is a pattern that repeats at defined intervals. 8-b/10-b encoding contains a character called the comma (b’0011111’
or b’1100000’) which is used by the comma detect circuit to align the received serial data back to its original byte
boundary. The decoder detects the K28.5 comma, generating a synchronization signal aligning the data to their 10-bit
boundaries for decoding. It then converts the data back into 8-bit data. It is important to note that the comma can be
either (b’0011111’) or the inverse (b’1100000’) depending on the running disparity. The TLK3114SA decoder detects
both patterns. Comma detect is not active in PRBS mode.
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