
RTL8208
2001/01/07
22
Rev.1.923
Name
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
I
J
K
T
R
H
V
V
V
V
V
V
V
V
V
V
4B Code
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
0000*
0101*
0101*
0000*
0000*
1000
0111
0111
0111
0111
0111
0111
0111
0111
0111
0111
5B Code
11110
01001
10100
10101
01010
01011
01110
01111
10010
10011
10110
10111
11010
11011
11100
11101
11111
11000
10001
01101
00111
00100
00000
00001
00010
00011
00101
00110
01000
01100
10000
11001
Definition
Data 0
Data 1
Data 2
Data 3
Data 4
Data 5
Data 6
Data 7
Data 8
Data 9
Data A
Data B
Data C
Data D
Data E
Data F
Idle
Start of stream Delimiter, Part 1
Start of stream Delimiter, Part 2
End of stream Delimiter, Part 1
End of stream Delimiter, Part 2
Transmit Error (used to force signaling errors)
Invalid code
Invalid code
Invalid code
Invalid code
Invalid code
Invalid code
Invalid code
Invalid code
Invalid code
Invalid code
*Treated as an invalid code (mapped to 0111) when received in data field.
4B5B Encoding
7.4.3 Link Monitor
In 100Base-TX mode, receive signal energy is detected by monitoring the receive pair for transitions in the signal level.
Signal levels are qualified using squelch detect circuits. When no signal or valid signals are detected on the receive pair, the
link monitor will enter and remain in the “Link Fail” state where only idle codes will be transmitted. When a valid signal is
detected on the receive pair for a minimum period of time, the link monitor will enter the “Link Pass” state and the transmit
and receive functions will be enabled.