Advance Information
MT89L86
required, the IMS register has to be initialized on
system power-up. In case of Identical I/O rates (DMO
bit LOW) at both inputs and outputs, the switching
configuration is selected by the two SCB bits as
shown in Table 8 (see IMS register). In case of
different I/O rates (DMO bit HIGH), the switching
configuration is always non-blocking with different
number of I/O streams which is defined by the IDR
and ODR bits (see IMS register).
register (SPS). The device clock for this operation is
4.096 MHz compatible to ST-BUS and GCI
interfaces. In addition, the per-channel selection
between variable or constant throughput delay is
available.
In the nibble switching configuration, 4-bit wide 32
Kb/s data channels can be switched within the
device. Every serial stream is run at 2.048 Mb/s and
transports 64 nibbles per frame. When the Nibble
Switching is selected at SCB bits, the 3.3V MT89L86
automatically assumes a 8-input x 4-output stream
configuration, providing a blocking switch matrix of
512 x 256 nibbles. If a non-blocking switch matrix is
required for nibble switching, the switch capacity is
reduced to 256 x 256 channel with a 4 input x 4
output configuration; the non-blocking matrix can be
arranged by the user by selecting any four of the 8
input streams. In nibble switching the interface clock
is 4.096 MHz.
Identical Input/Output Data Rates
When identical input/output data rate is selected by
the DMO bit, the I/O rate is determined by the IDR0-
1 bits, and the ODR0-1 bits are ignored. For each
data rate specified by the IDR bits, different switching
configurations can be selected in the SCB1-0 bits.
Serial Links with Data Rates at 2.048 Mb/s
When the 2.048 Mb/s data rate is selected at the IDR
bits, four different I/O configurations can be selected
by the SCB1-0 bits (see Table 8); 8 x 8, 16 x 8, 4 x 4
with stream pair selection and nibble switching.
Serial Links with Data Rates at 4.096 Mb/s
Two I/O configurations can be enabled by the SCB
bits when input and output data rates are 4.096 Mb/s
on each serial stream: 8 x 4 and 4 x 4. When 8 x 4
switching configuration is selected, a 512 x 256
channel blocking switch is available with serial
streams carrying 64, 64 Kb/s channels each. For this
operation, a 4.096 MHz interface clock equal to the
bit rate should be provided to the 3.3V MT89L86.
Only variable throughput delay mode is provided.
If 8 x 8 switching configuration is selected, a 256 x
256 channel non-blocking switching matrix is
available. In this configuration, the 3.3V MT89L86 is
configured with 8 input and 8 output data streams
with 32 64 Bit/s channels each. The interface clock
for this operation is 4.096 MHz with both ST-BUS and
GCI compatibilities and the per-channel selection
between variable and constant throughput delay
functions is provided.
In the 4 x 4 switching configuration, a 256 x 256
channel non-blocking switch is available with serial
streams carrying 64, 64 Kb/s channels each. In this
configuration, the interface clock is 4.096 MHz and
the per-channel selection between variable and
constant throughput delay operation is provided.
Figure 19 shows the timing for 4.096 Mb/s operation.
In 16 x 8 switching configuration, a 512 x 256
channel blocking switch matrix is available. This
configuration is available only when the CPU bus
interface is configured in the multiplexed mode. The
device clock in this application is 4.096 MHz, ST-
BUS or GCI compatible. This configuration only
provides variable throughput delay.
Serial Links with Data Rates at 8.192 Mb/s
Only 2 input x 2 output stream configuration is
available for 8.192 Mb/s, allowing a 256 x 256
channel non-blocking switch matrix to be
implemented. To enable this operation, the IDR bits
should be programmed to select 8.192 Mb/s rates
and the SCB bits have no effect. At 8.192 Mb/s,
every input and output stream provides 128 time-
slots per frame. The interface clock for this operation
should be 8.192 MHz. Figure 19 shows the timing for
8.192 Mb/s operation.
If the stream pair selection switching configuration is
selected, only four input and four outputs (4 pairs of
serial streams) can be selected by the CPU to be
internally connected to the switch matrix, totalling a
128 x 128 channel non-blocking switch. From the 10
serial link pairs available, two pairs are permanently
connected to the internal matrix (STi0/STo0 and
STi1/STo1). An internal stream pair selection
capability allows two additional pairs of serial links to
be selected from the remaining 8 pairs (from STi/
STo2 to STi9/STo9) and be connected to the internal
matrix along with the permanently connected STi0/
STo0 and STi1/STo1 streams. The two additional
pair of streams called stream pair A and stream pair
B, should be selected in the Stream Pair Selection
Table 1 summarizes the 3.3V MT89L86 switching
configurations for identical I/O data rates.
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