DP83849IF_14 Datasheet, PDF (50/104 Pages) Texas Instruments – PHYTER™ DUAL Industrial Temperature with Fiber Support (FX) and Flexible Port Switching Dual Port 10/100 Mb/s Ethernet Physical Layer Tranceiver

DP83849IF
SNOSAX8C – JUNE 2008 – REVISED APRIL 2009
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Table 6-1. 4B5B Code-Group Encoding/Decoding
DATA CODES
0
11110
0000
1
01001
0001
2
10100
0010
3
10101
0011
4
01010
0100
5
01011
0101
6
01110
0110
7
01111
0111
8
10010
1000
9
10011
1001
A
10110
1010
B
10111
1011
C
11010
1100
D
11011
1101
E
11100
1110
F
11101
1111
IDLE AND CONTROL CODES
H
00100
HALT code-group - Error code
I
11111
Inter-Packet IDLE - 0000⁽¹⁾
J
11000
First Start of Packet - 0101⁽¹⁾
K
10001
Second Start of Packet - 0101⁽¹⁾
T
01101
First End of Packet - 0000⁽¹⁾
R
00111
Second End of Packet - 0000⁽¹⁾
INVALID CODES
V
00000
V
00001
V
00010
V
00011
V
00101
V
00110
V
01000
V
01100
(1) Control code-groups I, J, K, T and R in data fields will be mapped as invalid codes, together with RX_ER asserted.
6.1.1 Code-group Encoding and Injection
The code-group encoder converts 4-bit (4B) nibble data generated by the MAC into 5-bit (5B) code-groups
for transmission. This conversion is required to allow control data to be combined with packet data code-
groups. Refer to Table 6-1 for 4B to 5B code-group mapping details.
The code-group encoder substitutes the first 8-bits of the MAC preamble with a J/K code-group pair
(11000 10001) upon transmission. The code-group encoder continues to replace subsequent 4B preamble
and data nibbles with corresponding 5B code-groups. At the end of the transmit packet, upon the
deassertion of Transmit Enable signal from the MAC, the code-group encoder injects the T/R code-group
pair (01101 00111) indicating the end of the frame.
After the T/R code-group pair, the code-group encoder continuously injects IDLEs into the transmit data
stream until the next transmit packet is detected (reassertion of Transmit Enable).
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Architecture
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