VITESSE

SEMICONDUCTOR CORPORATION

Data Sheet

VSC880

High Performance 16x16

Serial Crosspoint Switch

Page 14

G52191-0, Rev 4.2

01/05/01

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

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

Internet: www.vitesse.com

Where:

A[1:0]11=to switch chip, 00=from switch chip

B[1:0]00=Undefined,

01=Flow control channel,

10=Flow control channel,

11=Acknowledge to transceiver

D[19:0]20 bit data payload

2.2.2 CRQ Word Format on the Serial Data Lines to the Switch

The CRQ command word format as seen at the output of the transceiver is shown below. Two overhead bits are

added by the transceiver to designate a CRQ word to the receiving switch chip. The signal ARB, AOA and BRK are

used to control modes of operation in the switch chip. The serial data is transmitted with the MSB first.

Where:

B[1:0]00=Undefined,

01=Flow control channel,

10=Flow control channel,

11=Undefined

ARB1=Multi Queue arbitration

AOA1=Acknowledge on all connections granted, 0=Acknowledge on any connections granted

BRK 1=Break previous connection, 0=Do not break previous connection

C[0:15] Connection request bit map. Set bit high for each output requested

D[3:0] User defined data sent by transmitting port card

2.2.3 CRQ Word Format on the Serial Data Line From the Switch

The CRQ command word format as seen at the output of the switch chip is shown below. Two overhead bits are

added by the switch chip to designate a command word (00) to the transceiver. This word is sent on to the receiving

port card when an ACK is sent to the transmitting port card. The command word contains the current active

connections for this input in the switch chip. The serial data is transmitted with the MSB first.

33 32

31 30 29 28

27 26 25 24

23 22 21 20

19 18 17 16

15 14 13 12

11 10 09 08

07 06 05 04

03 02 01 00

A A

1 0

0 B B 1

1

0

0 1 1 0

D D D D

19 18 17 16

D D D D

15 14 13 12

D D D D

11 10 09 08

D D D D

07 06 05 04

D D D D

03 02 01 00

1 0 1 0

--------------- Data Payload ----------------

33 32

31 30 29 28 27

26 25 24

23 22 21 20

19 18 17 16

15 14 13 12

11 10 09 08

07 06 05 04

03 02 01 00

0 0

0 B B 1 0

1 0

A A B

R O R

C C C C

00 01 02 03

C C C C

04 05 06 07

C C C C

08 09 10 11

C C C C

12 13 14 15

D D D D

03 02 01 00

1 0 1 0

B A K

------ Connection Bits ------

--Data--