VITESSE
SEMICONDUCTOR CORPORATION
Data Sheet
High Performance Serial
Backplane Transceiver
VSC870
2.2.4 CRQ Format at the Transceiver TXIN[31:0] Interface
The connection request command word format at the TXIN[31:0] interface is shown below. The signals CT[2:0]
and MD[1:0] are used by the transceiver to control modes of operation that are described later in this section. For a
NULL CRQ word, set all the connection bits LOW.
31 30 29
X X X
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
X X X X
C C C
T T T
M M C C C C
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
D D
1 0
00 01 02 03
2 1 0
------ Connection Bits ------
-- Data--
Where:
CT[2:0]Control bits
MD[1:0] Mode; 00=Camp-on with Priority Mode, CT[2:0]=camp-on frequency
01=Camp-on with Recast Mode, CT[2:0]=number of CRQ commands to send
10=Multi Queue Mode, CT[2:0]=camp-on frequency
C[0:15]] Connection request bit map. Set bit high for each output requested.
C[0] is for port 0 and C[15] is for port 15.
D[3:0] User defined data sent by transmitting port card
2.2.5 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 signals AOA and BRK are used
to control modes of operation in the switch chip which are discussed in the VSC880 data sheet. The serial data is
transmitted with the MSB first.
33 32
0 0
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
1 0 1 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
B A K
------ Connection Bits ------
--Data--
Where:
B[1:0]00=Undefined,
01=Flow control channel,
10=Flow control channel,
11=Undefined
ARB1=Multi Queue arbitration, 0=Normal operation
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, C[0] for output port 0 etc
D[3:0] User defined data sent by transmitting port card
2.2.6 CRQ Word Format on the Serial Data Lines 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 command word contains the
current active connections for the transmitting port card. The serial data is transmitted with the MSB first.
© VITESSE SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
G52190-0, Rev 4.1
01/05/01
Page 15
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Internet: www.vitesse.com
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