vsc870 Vitesse Semiconductor Corp, vsc870 Datasheet - Page 27

• Manufacturer Part Number: vsc870
• Description: High Performance Serial Backplane Transceiver
• Manufacturer: Vitesse Semiconductor Corp

Data Sheet
VSC870
G52190-0, Rev 4.1
01/05/01
3.2 Data Encoding Format
transceivers at the port cards and the transceivers at the controller chip. The BYPASS signal is set HIGH so the
RXTYP[1:0] and TXTYP[1:0] are the direct representation of the overhead bits (B[1:0]) in the serial channels. For
data words, the user can use these bits for signaling to the receiving port card. Information such as start of frame and
end of frame can be passed through the switch in this manner. At the serial interface, the data words must be
scrambled to increase the signal edge transition density by setting the SCRAM input HIGH. The scrambling pattern is
reset at cell clock. The transceiver checks the bit pattern on IDLE words to detect a link error condition. The encoding
for these data types is described in the following table.
3.3 Transmitter Operation
CELLSYN input is set HIGH to allow the cell synchronization process. All words, either data words or command
The data word and command word format is described in section 1.0. These word formats are similar for both the
When BYPASS is set HIGH, all of the retransmit and self-routing functions in Packet Mode are disabled. The
TXTYP[1:0]
RXTYP[1:0]
0 0
0 1
1 0
1 1
Port Card
Port Card
© VITESSE SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
B[1:0]
Queuing
Queuing
System
0 0
0 1
1 0
1 1
System
Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]
VITESSE
SEMICONDUCTOR CORPORATION
VSC870
VSC870
Command Word
Data Word
Data Word
Data Word
Trans
Trans
Figure 10: Cell Based System
Datatypes
Internet: www.vitesse.com
No Scramble
Scramble
Scramble
Scramble
Communication Bus
SCRAM = 1
Switch Card
VSC880
Switch
Chip
No Scramble
No Scramble
No Scramble
No Scramble
SCRAM = 0
Scheduler
High Performance Serial
Arbiter/
Backplane Transceiver
IDLE word
No
No
No
Check
Error
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