VITESSE
SEMICONDUCTOR CORPORATION
Data Sheet
VSC870
1.2.1 Data Word Format at Transceiver Parallel Interface
High Performance Serial
Backplane Transceiver
Data words contain a 32 bit user defined payload which is sent between the transmitting and receiving port cards
as shown below. The RXTYP[1:0] and TXTYP[1:0] data word encoding format for different modes are described in
later sections.
31 30 29 28
D D D D
31 30 29 28
27 26 25 24
D D D D
27 26 25 24
23 22 21 20
D D D D
23 22 21 20
19 18 17 16
D D D D
19 18 17 16
15 14 13 12
D D D D
15 14 13 12
11 10 09 08
D D D D
11 10 09 08
07 06 05 04
D D D D
07 06 05 04
03 02 01 00
D D D D
03 02 01 00
--------------- Data Payload ----------------
Where:
D[31:0]32 bit data payload
1.2.2 Data Word Format on the Serial Data Lines
The data word format as seen at the serial output of the transceiver or switch chip is shown below. Two overhead
bits are added by the transceiver or switch chip to designate a data word to the receiving switch chip or transceiver.
The serial data is transmitted with the MSB first (B1, B0, D31, D30... D00).
33 32
B B
1 0
31 30 29 28
D D D D
31 30 29 28
27 26 25 24
D D D D
27 26 25 24
23 22 21 20
D D D D
23 22 21 20
19 18 17 16
D D D D
19 18 17 16
15 14 13 12
D D D D
15 14 13 12
11 10 09 08
D D D D
11 10 09 08
07 06 05 04
D D D D
07 06 05 04
03 02 01 00
D D D D
03 02 01 00
--------------- Data Payload ----------------
Where:
B[1:0]If BYPASS=0,01=Flow control channel,
10=Flow control channel,
11=Acknowledge from switch chip or data header to switch chip
If BYPASS = 1, RXTYP[1:0]=B[1:0]=TXTYP[1:0]
D[31:0]32 bit data payload
1.2.3 Command Word Format at Transceiver Parallel Interface
There are several command words that are used for sending information to the switch chip or a receiving port
card. The command word format at the transceiver parallel interface is shown below. IDLE words are discussed in the
next sections. A delay enable value can also be programmed into the transceiver for Packet Mode using this
command word.
31 30 29
X X X
28 27 26 25 24
C C C C C
04 03 02 01 00
-- Command --
23 22 21 20
D D D D
15 14 13 12
19 18 17 16
D D D D
11 10 09 08
15 14 13 12
D D D D
07 06 05 04
-- Data --
11 10 09 08
D D D D
03 02 01 00
07 06 05 04
X X X X
03 02 01 00
X X X X
Where:
C[4:0]Command type:
00XXX=Link Control (00111=IDLE word)
01XX0=Command word for transceiver (01000=set DLYEN/CCKIN value)
10XX0=Command word for switch
G52190-0, Rev 4.1
01/05/01
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VITESSE
SEMICONDUCTOR CORPORATION
• 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
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