MT90870 Zarlink Semiconductor, Inc., MT90870 Datasheet - Page 31

• Manufacturer Part Number: MT90870
• Description: Flexible 12k Digital Switch (F12kDX)
• Manufacturer: Zarlink Semiconductor, Inc.

Preliminary Information
6.0
The MT90870 incorporates two connection memories, Local Connection Memory and Backplane Connection
Memory.
6.1
The Local Connection Memory (LCM) is 16-bit wide with 4,096 memory locations to support the Local output
port. The most significant bit of each word, bit [15], selects the source stream from either the Backplane or the
Local port and determines the Backplane-to-Local or Local-to-Local data routing. Bits [14:13] select the control
modes of the Local output streams, namely the per-channel message and the per-channel high impedance
output control modes. In Connection Mode (Bit14 = LOW), Bits [12:0] select the source stream and channel
number as detailed in Table 5. In Message Mode (Bit14 = HIGH), Bits [12:8] are unused and Bits [7:0] contain
the message byte to be transmitted.
The Control Register bits MS2, MS1, and MS0 must be set to 000, respectively, to select the Local Connection
Memory for the Write and Read operations via the microprocessor port. See Section 7, Microprocessor Port,
and Section 13.1, Control Register (CR) for details on microprocessor port access.
6.2
The Backplane Connection Memory (BCM) is 16-bit wide with 8,192 memory locations to support the
Backplane output port. The most significant bit of each word, bit [15], selects the source stream from either the
Backplane or the Local port and determines the Local-to-Backplane or Backplane-to-Backplane data routing.
Bits [14:13] select the control modes of the Backplane output streams, namely the per-channel Message Mode
and the per-channel high impedance output control mode. In Connection Mode (Bit14 = LOW), Bits [12:0]
select the source stream and channel number as detailed in Table 5. In Message Mode (Bit14 = HIGH), Bits
[12:8] are unused and Bits [7:0] contain the message byte to be transmitted.
Connection Memory Description
Local Connection Memory
Backplane Connection Memory
(Backplane streams only)
Source Stream Bit Rate
Table 5 - Local and Backplane Connection Memory Configuration
16Mb/s
32Mb/s
2Mb/s
4Mb/s
8Mb/s
legal values:
legal values:
legal values:
legal values:
Source Stream No.
legal values: 0 - 15
0 - 31 (Backplane)
0 - 15 (Local)
0 - 31 (Backplane)
0 - 15 (Local)
0 - 31 (Backplane)
0 - 15 (Local)
0 - 31 (Backplane)
0 - 15 (Local)
[12:8]
[12:8]
[12:8]
[12:8]
[12:9]
Source Channel No.
legal values 0 - 127
legal values 0 - 255
legal values 0 - 511
legal values 0 - 31
legal values 0 - 63
[7:0]
[7:0]
[7:0]
[7:0]
[8:0]
MT90870
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