VSC880 查看數據表（PDF） - Vitesse Semiconductor
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VSC880 Datasheet PDF : 28 Pages
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Data Sheet
VSC880
VITESSE
SEMICONDUCTOR CORPORATION
High Performance 16x16
Serial Crosspoint Switch
33 32
00
31 30 29 28 27 26 25
0BB1010
10
24 23 22 21 20
B MMMM
R 00 01 02 03
K
19 18 17 16 15 14 13 12 11 10 09 08
MMMM MMMM MMMM
04 05 06 07 08 09 10 11 12 13 14 15
------ Active Connections ------
07 06 05 04
DDDD
03 02 01 00
--Data--
03 02 01 00
1010
Where:
B[1:0]00=Undefined,
01=Flow control channel,
10=Flow control channel,
11=Acknowledge
BRK1=This is the CRQ word for the next packet. This bit is used to break the current connection.
M[0:15]Current outputs the transmitting channel is connected to
D[3:0] User defined data sent by transmitting port card
2.3 Receiver Operation
In Packet Mode, the receiver looks for connection request (CRQ) words from the transceiver. All data words and
IDLE words are passed on directly to the switch matrix. If BRK is HIGH, the current connection will be broken
before processing the new connection request word. When BRK is LOW, the switch does not break current
connections when making a new request. When AOA is HIGH, the switch will send an ACK only if the current
switch connections match the C[0:15] bit field. When AOA is LOW, an ACK is sent back to the transceiver when any
connection in the C[0:15] bit field is granted. In both cases, a response word is also returned to the transceiver from
the switch. The response word can be embedded into an IDLE word or CRQ word that is sent back to the transceiver.
If the transceiver makes a CRQ that requires a response (i.e., a multicast CRQ), the switch uses the flow control
channel to force an IDLE word into the receiving data stream by forcing the internal ready to receive (RTR) signal
low for one word clock (see the VSC870 data sheet).
The bit field C[0:15] is used to designate the output channels that are to be acted upon for a connection request
operation. To request an output to connect to, set the corresponding bit HIGH. Multiple bits can be set HIGH at the
same time for multicast. The sending port card can include 4 bits of data (D[3:0]) in the CRQ word that will be passed
on to the destination port card. Two example word sequences from the transceiver on the serial interface are shown in
the Figure 7. The two overhead bits (BB) are used for signaling on data words (see the VSC870 date sheet).
G52191-0, Rev 4.2
01/05/01
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