VITESSE

SEMICONDUCTOR CORPORATION

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7212

Gigabit Interconnect Chip

G52268-0, Rev 3.3

Page 5

04/10/01

© VITESSE SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012

Tel: (800)-VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com

Internet: www.vitesse.com

8B/10B Encoder

The VSC7212 contains an 8B/10B encoder which translates the 8-bit input data on T(7:0) into a 10-bit

encoded data character. A C/D input is also provided which, along with KCHAR, allow the transmission of

special Fibre Channel Kxx.x characters (see Table 2). Note that KCHAR is a static input, and does NOT have

the same input timing as T(7:0), C/D and WSEN. Normally C/D is LOW in order to transmit data. If C/D is

HIGH and KCHAR is LOW, then a Fibre Channel defined IDLE Character (K28.5 = ‘0011111010’ or

‘1100000101’ depending on disparity) is transmitted and T(7:0) is ignored. If C/D is HIGH and KCHAR is

HIGH, a Kxx.x character is transmitted as determined by the data on T(7:0) (see Table 3). Data patterns other

than those defined in Table 3 produce undefined 10B encodings.

Table 2: Transmit Data Controls

Table 3: Special Characters (Selected when C/D and KCHAR are HIGH)

Encoder Bypass Mode

When ENDEC is LOW the 8B/10B encoder is bypassed and a 10-bit input character T(7:0) is serialized

onto PTX/RTX with bit T0 is transmitted first. The C/D input becomes T8, and WSEN becomes T9. The

KCHAR input becomes ENCDET which is not used in the transmitter, but when HIGH, enables “Comma”

detection in the receiver. Refer to the “Decoder Bypass Mode” section for a description of this mode of

operation in the receiver. The latency through the transmitter is reduced by one character time when ENDEC is

LOW. This mode of operation is similar to a 10-bit interface commonly found in serializer/deserializers for the

Fibre Channel (e.g., VSC7125) and Gigabit Ethernet markets (e.g., VSC7135).

WSEN

C/D

KCHAR

Encoded 10-bit Output

0

0

X

Data Character

0

1

0

IDLE Character (K28.5)

0

1

1

Special Kxx.x Character

1

X

X

16-Character Word Sync Sequence

Code

T(7:0)

Comment

Code

T(7:0)

Comment

K28.0

000 11100

User Defined

K28.6

110 11100

User Defined

K28.1

001 11100

User Defined

K28.7

111 11100

Test Only

K28.2

010 11100

User Defined

K23.7

111 10111

User Defined

K28.3

011 11100

User Defined

K27.7

111 11011

User Defined

K28.4

100 11100

User Defined

K29.7

111 11101

User Defined

K28.5

101 11100

IDLE

K30.7

111 11110

User Defined