LAN83C183 Datasheet, PDF (21/113 Pages) SMSC Corporation – FAST ETHERNET PHYSICAL LAYER DEVICE

Table 1.4 4B/5B Symbol Mapping
Symbol Name Description 5B Code 4B Code
0
Data 0
11110
0000
1
Data 1
01001
0001
2
Data 2
10100
0010
3
Data 3
10101
0011
4
Data 4
01010
0100
5
Data 5
01011
0101
6
Data 6
01110
0110
7
Data 7
01111
0111
8
Data 8
10010
1000
9
Data 9
10011
1001
A
Data A
10110
1010
B
Data B
10111
1011
C
Data C
11010
1100
D
Data D
11011
1101
E
Data E
11100
1110
F
Data F
11101
1111
I
Idle
11111
0000
J
SSD #1
11000
0101
K
SSD #2
10001
0101
T
ESD #1
01101
0000
R
ESD #2
00111
0000
H
Halt
00100 Undefined
---
Invalid codes All others¹
0000
1. These 5B codes are not used. The decoder converts them
to a 4B code of 0000. The encoder converts the 4B 0000
code to the 5B 11110 code, as shown in symbol 0.
The 4B5B encoder takes 4B (four-bit) nibbles from the Transmit MAC block, converts
them into 5B (five-bit) words according to Table 1.4, and sends the 5B words to the
scrambler. The 4B5B encoder also substitutes the first eight bits of the preamble with
the Start of Stream Delimiter (SSD) (/J/K/ symbols) and adds an End of Stream
Delimiter (ESD) (/T/R/ symbols) to the end of each packet, as defined in IEEE 802.3
and shown in Figure 1.2. The 4B5B encoder also fills the period between packets
(idle period), with a continuous stream of idle symbols, as shown in Figure 1.2.
1.2.3.2 MANCHESTER ENCODER (10 MBITS/S)
The Manchester Encoder shown in Figure 1.1 is used for 10 Mbits/s operation. It
combines clock and non-return to zero inverted (NRZI) data such that the first half of
SMSC DS – LAN83C183
21
Rev. 12/14/2000