10/100 Non-PCI Ethernet Single Chip MAC + PHY

Datasheet

Table 7.1 4B/5B Symbol Mapping (continued)

SYMBOL NAME

DESCRIPTION

5B CODE

4B CODE

 

 

 

 

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 others*

0000*

 

 

 

 

*These 5B codes are not used. For decoder, these 5B codes are decoded to 4B 0000. For encoder, 4B 0000 is encoded to 5B 11110, as shown in symbol Data 0.

The 4B5B decoder detects SSD, ESD and codeword errors in the incoming data stream as specified in IEEE 802.3. These errors are indicated by asserting RX_ER output while the errors are being transmitted across RXD[3:0], and they are also indicated in the serial port by setting SSD, ESD, and codeword error bits in the PHY MI serial port Status Output register.

Manchester Decoder - 10 Mbps

In Manchester coded data, the first half of the data bit contains the complement of the data, and the second half of the data bit contains the true data. The Manchester decoder in the LAN91C111 converts the Manchester encoded data stream from the TP receiver into NRZ data for the controller interface by decoding the data and stripping off the SOI pulse. Since the clock and data recovery block has already separated the clock and data from the TP receiver, the Manchester decoding process to NRZ data is inherently performed by that block.

Revision 1.91 (08-18-08)

28

SMSC LAN91C111 REV C

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