MT90812 Mitel Networks Corporation, MT90812 Datasheet - Page 14

• Manufacturer Part Number: MT90812
• Description: Integrated Digital Switch (IDX)
• Manufacturer: Mitel Networks Corporation

MT90812
4.0
The switching function of the MT90812 is described in four parts:
•
•
•
•
Each will be described below with reference to Figure 1 - “Functional Block Diagram”. This is followed by a
more detailed description of Connect Memory in Section 4.2.
4.1
4.1.1
The serial data incoming to the MT90812 is converted into parallel format (8 bits per channel) with the parallel
to serial converters for both the Local and Expansion Bus streams. This data is written to consecutive locations
in Data Memory.
The two local TDM streams, STi/o0 and STi/o1, operate at 2.048 Mb/s for a total of 64 channels per frame. The
64 bytes are stored in the Local Data Memory page in locations 00
Table 2.
4.1.2
In TDM Link mode, the expansion bus rate can be set to 2.048, 4.096 or 8.192 Mb/s, where the number of
channels used for the expansion bus stream are 32, 64 and 128, respectively. In Data Memory, 128 bytes are
reserved in the Expansion Data Memory page. If there are only 32 or 64 channels (i.e. at 2.048 or 4.096 Mb/s)
then the first 32 or 64 locations of the 128 reserved for the expansion bus are used.
In IDX Link mode, the Expansion Bus rate is set to 8.192 Mb/s. There are 96 channels incoming from EST0
and 32 channels from ESTI, for a total of 128 incoming channels read into Expansion Data Memory.
4.1.3
There are 64 locations in Local Data Memory reserved for the incoming channels of the Local TDM streams
and 128 locations in Expansion Data Memory, for the incoming channels of the Expansion Bus. In addition,
there are another 32 locations of Local Data Memory reserved for the Tone generator. Refer to the Memory
Map in Table 2.
For each output channel there is an associated Connect Memory location. There are 128 locations for the
outgoing expansion bus channels and 64 for the local TDM streams.
4.1.4
When the MT90812 switches data from input channels to outgoing channels, the address for Data Memory is
read from the Connection Memory location corresponding to the desired output channel. In Message Mode,
output data is read directly from the Connection Memory location corresponding to the output channel. The
details for setting up the connections are given in the following section.
4.2
The use of Connection Memory in the MT90812 is described in three parts:
•
10
How incoming data from the Local TDM streams are transferred to Data Memory.
How incoming data from the Expansion Bus is transferred to Data Memory for both IDX Link and TDM
Link modes.
Connect Memory and Data Memory structure.
How output data can be switched from either Data Memory or Connect Memory.
Connection Memory usage for Switch Connection or Message Mode
Switching
Switching Functions
Connection Memory
Data Transfer from Local TDM Streams to Data Memory
Data Transfer from the Expansion Bus to Data Memory
Connect Memory and Data Memory Structure
Switching Output Data from Either Data Memory or Connect Memory
H
to 3F
H
. Refer to the Memory Map in
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