MT90871 Zarlink Semiconductor, MT90871 Datasheet - Page 12

• Manufacturer Part Number: MT90871
• Description: Flexible 8K Digital Switch (F8KDX)
• Manufacturer: Zarlink Semiconductor

2.2.3.1
The bit rate for each output stream is selected by writing to a dedicated Backplane Output Bit Rate Register
(BOBRR0-15). Refer to Table 44, Backplane Output Bit Rate Register (BOBRRn) Bits.
Operation of stream data in the Connection Mode or the Message Mode is determined by the state of the BMM
bit, and the channel High-impedance state is controlled by the BE bit of the Backplane Connection Memory.
The data source (i.e. from the Local or Backplane Data Memory) is determined by the BSRC bit of the
Backplane Connection Memory. Refer to section 6.2 "Backplane Connection Memory" and section 12.4
"Backplane Connection Memory Bit Definition".
2.3
The Backplane frame pulse (FP8i) is an 8kHz input signal active for 122ns or 244ns at the frame boundary. The
FPW bit in the Control Register must be set according to the applied pulse width. See Pin Description and
Table 13, Control Register Bits, for details.
The active state and timing of FP8i may conform either to the ST-BUS or to the GCI-BUS as shown in Figure 6,
Local Port Timing Diagram for 2,4,8 and 16Mb/s stream rates, and Figure 7, Backplane Port Timing Diagram
for 2, 4, 8, and 16Mb/s stream rates. The MT90871 will automatically detect whether an ST-BUS or a GCI-BUS
style frame pulse is being used for the master frame pulse (FP8i). The active edge of the input clock (C8i) shall
be selected by the state of the Control Register bit C8IPOL. For the purposes of describing the device
12
BSTi/BSTo0-15
BSTi/BSTo0-15
BSTi/BSTo0-15
BSTi/BSTo0-15
BSTi/BSTo0-15
BSTi/BSTo0-15
BSTi/BSTo0-15
BSTi/BSTo0-15
FP8i (ST-BUS)
(8.192MHz)
(16Mb/s) GCI
C8i (ST-BUS)
(16Mb/s) ST
(4Mb/s) GCI
(8Mb/s) GCI
(2Mb/s) GCI
(8.192MHz)
C8i (GCI)
(4Mb/s) ST
(8Mb/s) ST
(2Mb/s) ST
FP8i (GCI)
(8kHz)
(8kHz)
Backplane Output Port
Backplane Frame Pulse Input and Master Input Clock Timing
Figure 7 - Backplane Port Timing Diagram for 2, 4, 8, and 16Mb/s stream rates
0
7
0
7
1
6
0
7
0
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7
0
7
0
6
1
7
0
5
2
6
1
Channel 0
Channel 0
Channel 0
Channel 0
Channel 0
Channel 0
Channel 0
Channel 0
4
3
7
0
Zarlink Semiconductor Inc.
3
4
5
2
2
5
6
1
1
6
4
3
0
7
3
4
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1
1
6
5
2
Channel 255
Channel 255
Channel 127
Channel 127
2
5
Channel 63
Channel 63
Channel 31
Channel 31
4
3
0
7
3
4
1
6
2
5
0
7
1
6
Data Sheet
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7
0
7
7
0
7
0
7
0
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0