
LXT9785 and LXT9785E Advanced 8-Port 10/100 Mbps PHY Transceivers
146
Datasheet
Document Number: 249241
Revision Number: 010
Revision Date: 30-May-2006
4.9.3
PMA Sublayer
The 100BASE-X PMA protocol uses the 4B/5B data encoding scheme to encode/decode the data
streams. The coding scheme is shown in
Table 46.
Table 46. 4B/5B Coding
Code Type
4B Code
3 2 1 0
Name
5B Code
4 3 2 1 0
Interpretation
0 0 0 0
0
1 1 1 1 0
Data 0
0 0 0 1
1
0 1 0 0 1
Data 1
0 0 1 0
2
1 0 1 0 0
Data 2
0 0 1 1
3
1 0 1 0 1
Data 3
0 1 0 0
4
0 1 0 1 0
Data 4
0 1 0 1
5
0 1 0 1 1
Data 5
0 1 1 0
6
0 1 1 1 0
Data 6
DATA
0 1 1 1
7
0 1 1 1 1
Data 7
1 0 0 0
8
1 0 0 1 0
Data 8
1 0 0 1
9
1 0 0 1 1
Data 9
1 0 1 0
A
1 0 1 1 0
Data A
1 0 1 1
B
1 0 1 1 1
Data B
1 1 0 0
C
1 1 0 1 0
Data C
1 1 0 1
D
1 1 0 1 1
Data D
1 1 1 0
E
1 1 1 0 0
Data E
1 1 1 1
F
1 1 1 0 1
Data F
IDLE
undefined
I 1
1 1 1 11
Idle. Used as inter stream fill code.
0 1 0 1
J 2
1 1 0 0 0
Start-of-Stream Delimiter (SSD),
part 1 of 2.
CONTROL
0 1 0 1
K
2
1 0 0 0 1
Start-of-Stream Delimiter (SSD),
part 2 of 2.
undefined
T 3
0 1 1 0 1
End-of-Stream Delimiter (ESD),
part 1 of 2.
undefined
R 3
0 0 1 1 1
End-of-Stream Delimiter (ESD),
part 2 of 2.
undefined
H
4
0 0 1 0 0
Transmit Error. Used to force
signaling errors.
undefined
Invalid
0 0 0 0 0
Invalid
undefined
Invalid
0 0 0 0 1
Invalid
undefined
Invalid
0 0 0 1 0
Invalid
INVALID
undefined
Invalid
0 0 0 1 1
Invalid
undefined
Invalid
0 0 1 0 1
Invalid
undefined
Invalid
0 0 1 1 0
Invalid
undefined
Invalid
0 1 0 0 0
Invalid
undefined
Invalid
0 1 1 0 0
Invalid
undefined
Invalid
1 0 0 0 0
Invalid
undefined
Invalid
1 1 0 0 1
Invalid
1. The /I/ (Idle) code group is sent continuously between frames.
2. The /J/ and /K/ (SSD) code groups are always sent in pairs; /K/ follows /J/.
3. The /T/ and /R/ (ESD) code groups are always sent in pairs; /R/ follows /T/.
4. An /H/ (Error) code group is used to signal an error condition.