VSC7212 Datasheet, PDF (5/34 Pages) Vitesse Semiconductor Corporation – Gigabit Interconnect Chip

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Preliminary Data Sheet
VSC7212
Gigabit Interconnect Chip
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
WSEN
0
0
0
1
C/D
KCHAR
Encoded 10-bit Output
0
X
Data Character
1
0
IDLE Character (K28.5)
1
1
Special Kxx.x Character
X
X
16-Character Word Sync Sequence
Table 3: Special Characters (Selected when C/D and KCHAR are HIGH)
Code
K28.0
K28.1
K28.2
K28.3
K28.4
K28.5
T(7:0)
000 11100
001 11100
010 11100
011 11100
100 11100
101 11100
Comment
User Defined
User Defined
User Defined
User Defined
User Defined
IDLE
Code
K28.6
K28.7
K23.7
K27.7
K29.7
K30.7
T(7:0)
110 11100
111 11100
111 10111
111 11011
111 11101
111 11110
Comment
User Defined
Test Only
User Defined
User Defined
User Defined
User Defined
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).
G52268-0, Rev 3.3
04/10/01
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Tel: (800)-VITESSE • FAX: [phone] • Email: [e-mail]
Internet: www.vitesse.com
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