mt90870ag2 Zarlink Semiconductor, mt90870ag2 Datasheet - Page 37

• Manufacturer Part Number: mt90870ag2
• Description: Flexible 12 K Digital Switch F12kdx
• Manufacturer: Zarlink Semiconductor

The BCSTo0-3 outputs transmit serial data (channel control bits) at 16.384 Mb/s, with each bit representing the per-
channel high impedance state for specific streams. Four output streams are allocated to each control line as
follows:
•
•
•
•
•
The Channel Control Bit location, within a frame period, for each channel of the Backplane output streams is
presented in Table 4, BCSTo Allocation of Channel Control Bits to the Output Streams (32 Mb/s Mode)
The BCSTo0-3 outputs data at a constant data-rate of 16.384 Mb/s and all output streams, BSTo0-15, operate at a
data-rate of 32.768 Mb/s.
As an aid to the description, the channel control bit for a single channel on specific streams is presented, with
reference to Table 4:
Figure 15, Backplane Port External High Impedance Control Timing (32 Mb/s Mode) shows the channel control bits
for BCSTo0, BCSTo1, BCSTo2 and BCSTo3.
(See also Pin Description)
BCSTo0 outputs the channel control bits for streams BSTo0, 4, 8, and 12.
BCSTo1 outputs the channel control bits for streams BSTo1, 5, 9, and 13.
BCSTo2 outputs the channel control bits for streams BSTo2, 6, 10, and 14.
BCSTo3 outputs the channel control bits for streams BSTo3, 7, 11, and 15.
(1) The Channel Control Bit corresponding to Stream 0, Channel 0, BSTo0_Ch0, is transmitted on
BCSTo0 and is advanced, relative to the Frame Boundary, by six periods (clock period no. 2043) of
C16o.
(2) The Channel Control Bit corresponding to Stream 12, Channel 0, BSTo12_Ch0, is transmitted on
BCSTo0 in advance of the Frame Boundary by three periods (clock period no. 2046) of output clock,
C16o. Similarly, the Channel Control Bits for BSTo13_Ch0, BSTo14_Ch0 and BSTo15_Ch0 are
advanced relative to the Frame Boundary by three periods of C16o, on BCSTo1, BCSTo2 and BCSTo3,
respectively.
(3) For stream BSTo4 the value of the Channel Control Bit for Channel 510 will be transmitted during the
C16o clock period no. 2036 on BCSTo0.
(4) For stream BSTo5 the value of the Channel Control Bit for Channel 4 will be transmitted during the
C16o clock period no. 12 on BCSTo1.
2039
2040
2041
2042
2043
2044
2045
2046
2047
Period
C16o
Table 4 - BCSTo Allocation of Channel Control Bits to the Output Streams
1
0
4
8
12
0
4
8
12
0
BCSTo0
3-1
3-2
Allocated Stream No.
1
5
9
13
1
5
9
13
1
BCSTo1
3-2
Zarlink Semiconductor Inc.
2
6
10
14
2
6
10
14
2
MT90870
BCSTo2 BCSTo3
(32 Mb/s Mode)
3-2
37
3
7
11
15
3
7
11
15
3
3-2
Ch 511
Ch 511
Ch 511
Ch 511
Ch 0
Ch 0
Ch 0
Ch 0
Ch 1
Channel No.
32 Mb/s
2
Data Sheet