2-63

Features

256 x 256 or 512 x 256 switching configurations

8-bit or 4-bit channel switching capability

Guarantees frame integrity for wideband
channels

Automatic identification of ST-BUS/GCI
interfaces

Accepts serial streams with data rates up to
8.192 Mb/s

Rate conversion from 2.048 Mb/s to 4.096 or
8.192 Mb/s and vice-versa

Programmable frame offset on inputs

Per-channel three-state control

Per-channel message mode

Control interface compatible to Intel/Motorola
CPUs

Low power consumption

Applications

Medium size digital switch matrices

Hyperchannel switching (e.g., ISDN H0)

MVIP

interface functions

Serial bus control and monitoring

Centralized voice processing systems

Voice/Data multiplexer

32 kbit/s channel switching

Description

The Multiple Rate Digital Switch (MRDX) is an
upgraded version of MITEL's MT8980D Digital
Switch (DX). It is pin compatible with the MT8980D
and retains all of its functionality. This device is
designed to provide simultaneous connections (non-
blocking) for up to 256 64kb/s channels or blocking
connections for up to 512 64kb/s channels. The
serial inputs and outputs connected to MT8986 may
have 32 to 128 64kb/s channels per frame with data
rates ranging from 2048 up to 8192 kb/s. The
MT8986 provides per-channel selection between
variable and constant throughput delays allowing
voice and grouped data channels to be switched
without corrupting the data sequence integrity.

In addition, the MT8986 can be used for switching of
32 kb/s channels in ADPCM applications. The
MT8986 is ideal for medium size mixed voice and
data switching/processing applications.

Figure 1 - Functional Block Diagram

STi0
STi1
STi2
STi3
STi4
STi5
STi6
STi7
STi8
STi9

* STi10
* STi11
* STi12
* STi13
* STi14
* STi15

STo0

STo1

STo2

STo3

STo4

STo5

STo6

STo7

STo8 *

STo9 *

CLK FR AS/

ALE

DS
RD

R/W
WR

A0/
A7

DTA AD7/

AD0

CSTo

ODE

Serial

Parallel

Converter

Multiple Buffer Data

Memory

Output

MUX

Parallel

Serial

Converter

Timing

Unit

Internal Registers

Microprocessor

Interface

Connection

Memory

* 44 Pin only

ISSUE 3

May 1995

MT8986

Multiple Rate Digital Switch

CMOS ST-BUS

FAMILY

Ordering Information

MT8986AC

40 Pin Ceramic DIP

MT8986AE

40 Pin Plastic DIP

MT8986AP

44 Pin PLCC

MT8986AL

44 Pin QFP

-40

C to +85

MT8986

2-64

Figure 2 - Pin Connections

Pin Description

Pin #

Name

Description

DIP

PLCC

QFP

DTA

Data Acknowledgement (Open Drain Output). This active low output indicates
that a data bus transfer is complete. A 10k

pull-up resistor is required at this

output.

2-7

2-5
7-9

41-43

1-3

STi0-5

ST-BUS Inputs 0 to 5 (Inputs). Serial data input streams. These streams may
have data rates of 2.048, 4.096 or 8.192 Mbit/s with 32, 64 or 128 channels,
respectively.

i
0

i
1

i
2

/AL

ODE

/STo

STo3
STo4
STo5
STo6/A6
STo7/A7
VSS
AD0
AD1
AD2
AD3
AD4

i
1

/
A3

i
1

/
A4

i
3

/
A

DS/

i
1

/
S

AD5

AD6

AD7

44 PIN QFP

/WR

CST

2
3
4
5
6
7
8
9

10
11
12
13
14
15
16
17
18
19
20

40 PIN DIP

STi3
STi4
STi5

STi6/A6
STi7/A7

VDD

CLK

STi8/A0
STi9/A1

STi10/A2

40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21

CSTo
ODE
STo0
STo1
STo2
STo3
STo4
STo5

STo6/A6
STo7/A7

VSS
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
CS

DTA

STi0
STi1
STi2
STi3
STi4
STi5

STi6/A6
STi7/A7

VDD

CLK

A0
A1
A2
A3
A4
A5

DS/RD

R/W\WR

2
3
4
5
6
7
8
9
10

33
32
31
30
29
28
27
26
25
24

6 5 4 3 2

44 43 42 41 40

7
8
9
10
11
12
13
14
15
16

39
38
37
36
35
34
33
32
31
30

18 19 20 21 22

24 25 26 27 28

STi

AS/A

ODE

STo

STi

STo3
STo4
STo5
STo6/A6
STo7/A7
VSS
AD0
AD1
AD2
AD3
AD4

i
1

/
A

i
1

/
A

STi

DS/

/WR

CST

STi3
STi4
STi5

STi6/A6
STi7/A7

VDD

CLK

STi8/A0
STi9/A1

STi10/A2

44 PIN PLCC

MT8986

2-65

STi6/A6 ST-BUS Input 6/Addr.6 input (Input). The function of this pin is determined by

the switching configuration enabled. If non-multiplexed CPU bus is used along
with a higher input rate of 8.192 or 4.096 Mb/s, this pin provides A6 address
input function. For 2.048 and 4.096 Mb/s (8x4) applications or when multiplexed
CPU bus (44 pin only) is selected, this pin assumes STi6 function. See Control
Register bits description and Tables 1, 2, 6 & 7 for more details.
Note that for applications where both A6 and STi6 inputs are required
simultaneously (e.g., 8 x 4 switching configuration at 4.096 Mb/s or rate
conversion between 2.048Mb/s to 4.196 or 8.192 Mb/s) the A6 input should be
connected to pin STo6/A6.

STi7/A7 ST-BUS Input 7/Addr.7 input (Input): The function of this pin is determined by

the switching configuration enabled. If non-multiplexed CPU bus is used along
with a higher input rate of 8.192 Mb/s, this pin provides A7 address input
function.
For 2.048 and 4.096 Mb/s (8x4) applications or when multiplexed CPU bus
(44 pin only) is selected, this pin assumes STi7 function. See Control Register
bits description and Tables 1, 2, 6 & 7 for more details.
Note that for applications where both A7 and STi7 inputs are required
simultaneously (e.g., 2.048 to 8.192 Mb/s rate conversion) the A7 input should
be connected to pin STo7/A7.

+5 Volt Power Supply.

Frame Pulse (Input). This input accepts and automatically identifies frame
synchronization signals formatted according to ST-BUS and GCI interface
specifications.

CLK

Clock (Input). Serial clock for shifting data in/out on the serial streams.
Depending on the serial interface speed selected by IMS (Interface Mode Select)
register, the clock at this pin can be 4.096 or 8.192 MHz.

13-15 15-17

9-11

A0-2/

STi8-10

Address 0-2 / Input Streams 8-10 (Input). When non-multiplexed CPU bus is
selected, these lines provide the A0-A2 address lines to MT8986 internal
registers. When 16x8 switching configuration is selected (in 44 pin only), then
these pins are ST-BUS serial inputs 8 to 10 receiving data at 2.048 Mb/s.

16-18 19-21 13-15

A3-5/

STi11-13

Address 3-5 / Input Streams 11-13 (Input). When non-multiplexed CPU bus is
selected, these lines provide the A3-A5 address lines to MT8986 internal
registers. When 16x8 switching configuration is selected (in 44 pin only), then
these pins are ST-BUS serial inputs 11 to 13 receiving data at 2.048 Mb/s.

DS/RD

Data Strobe/Read (Input). When non-multiplexed CPU bus or Motorola
multiplexed bus (44 pin only) are selected, this input is DS. This active high input
works in conjunction with CS to enable read and write operation.
For Intel/National multiplexed bus (44 pin only), this input is RD. This active low
input configures the data bus lines (AD0-AD7) as outputs.

R/W\WR Read/Write \ Write (Input). In case of non-multiplexed and Motorola multiplexed

buses (44 pin only), this input is R/W. This input controls the direction of the data
bus lines (AD0-AD7) during a microprocessor access.
With Intel/National multiplexed timing (44 pin only), this input is WR. This active
low signal configures the data bus lines (AD0-AD7) as inputs.

Chip Select (Input). Active low input enabling a microprocessor read or write of
the control register or internal memories.

22-29 25-27

29-33

19-21
23-27

AD7-

AD0

Data Bus (Bidirectional): These pins provide microprocessor access to the
internal control registers, connection memories high and low and data memories.
In multiplexed bus mode (44 pin) these pins also provide the input address to the
internal Address Latch circuit.

Ground.

Pin Description (continued)

Pin #

Name

Description

DIP

PLCC

QFP

MT8986

2-66

STo7/A7 ST-BUS Output 7/Address 7 input (Three-state output/input). The function of

this pin is determined by the switching configuration enabled. If non-multiplexed
CPU bus is used along with data rates employing 8.192 Mb/s rates, this pin
provides A7 address input function. For 2.048 Mb/s applications or when
multiplexed CPU bus (44 pin only) is selected, this pin assumes STo7 function.
See Tables 1, 2, 6 & 7 for more details.

Note that for applications where A7 input and STo7 output are required
simultaneously (e.g., 8.192 to 2.048 Mb/s rate conversion), the A7 input should
be connected to pin STi7/A7.

STo6/A6 ST-BUS Output 6/Address 6 input (Three-state output/input). The function of

this pin is determined by the switching configuration enabled. If non-multiplexed
CPU bus is used along with a higher data rate employing 8.192 or 4.096 Mb/s,
this pin provides the A6 address input function. For 2.048 Mb/s applications or
when multiplexed CPU bus (44 pin only) is selected, this pin assumes STo6
function. See Tables 1, 2, 6 & 7 for more details.
Note that for applications where both A6 input and STo6 output are required
simultaneously (e.g., 4.096 to 2.048 Mb/s or 8.192 to 2.048 Mb/s rate conversion
applications), the A6 input should be connected to pin STi6/A6.

33-38 37-39

41-43

31-33
35-37

STo5-0 ST-BUS Outputs 5 to 0 (Three-state Outputs). Serial data output streams.

These serial streams may be composed of 32, 64 and 128 channels at data rates
of 2.048, 4.096 or 8.192 Mbit/s, respectively.

ODE

Output Drive Enable (Input). This is the output enable input for the STo0 to
STo9 serial outputs. If this input is low STo0-9 are high impedance. If this input is
high each channel may still be put into high impedance by using per-channel
control bits in Connect Memory High.

CSTo

Control ST-BUS Output (Output). This is a 2.048 Mb/s output containing 256
bits per frame. The level of each bit is determined by the CSTo bit in the Connect
Memory high locations.

AS/ALE Address Strobe or Latch Enable (Input). This input is only used if multiplexed

bus is selected via the IM input pin (44 pin only).
The falling edge of this signal is used to sample the address into the address
latch circuit. In case of non-multiplexed bus, this input is not required and should
be left open.

CPU Interface Mode (Input). If HIGH, this input configures MT8986 in
multiplexed microprocessor bus mode. If this input pin is not connected or
grounded, the MT8986 assumes non-multiplexed CPU interface.

STi15/

STo9

ST-BUS Input 15 / ST-BUS Output 9 (Input/three-state output). This pin is only
used if multiplexed CPU bus is selected. If 16-input x 8-output switching
configuration is enabled in the SCB bits (IMS register), this pin is an input
receiving serial ST-BUS stream 15 at a data rate of 2.048 Mbit/s.
If Stream Pair Selection capability is enabled (see switching configuration
section), this pin is the ST-BUS stream 9 output.
When non-multiplexed bus structure is used, this pin should be left open.

STi14/

STo8

ST-BUS Input 14 / ST-BUS Output 8 (Input/three-state output). This pin is only
used if multiplexed CPU bus is selected. If 16-input x 8-output switching
configuration is enabled in the SCB bits (IMS register), this pin is an input that
receives serial ST-BUS stream 14 at a data rate of 2.048 Mbit/s.
If Stream Pair Selection capability is enabled (see switching configuration
section), this pin is the ST-BUS stream 8 output.
When non-multiplexed bus structure is used, this pin should be left open.

Pin Description (continued)

Pin #

Name

Description

DIP

PLCC

QFP

MT8986

2-67

DEVICE OVERVIEW

With the integration of voice, video and data services
in the same network, there has been an increasing
demand for systems which ensure that data at N x
64 kbit/s rates maintain sequence integrity while
being transported through time-slot interchange
circuits. This requirement demands time-slot
interchange devices which perform switching with
constant throughput delay for wideband data
applications while guaranteeing minimum delay for
voice channels.

The MT8986 device meets the above requirement
and allows existing systems based on the MT8980D
to be easily upgraded to maintain the data integrity
when wideband data is transported. The device is
designed to switch 32, 64 or N x 64 kbit/s data. The
MT8986 can provide frame integrity for data
applications and minimum throughput switching
delay for voice applications on a per channel basis.

The serial streams of the MT8986 device can
operate at 2.048, 4.096 or 8.192 Mbit/s and are
arranged in 125 µs wide frames which contain 32, 64
and 128 channels, respectively. In addition, a built-in
rate conversion circuit allows the user to
interconnect various backplane speeds like 2.048 or
4.096 or 8.192 Mb/s while maintaining the control of
throughput delay function on a per-channel basis.

By using Mitel Message mode capability, the
microprocessor can access input and output time-
slots on a per channel basis to control external
circuits or other ST-BUS devices. The MT8986
automatically identifies the polarity of the frame
synchronization input signal and configures its serial
port to be compatible to both ST-BUS and GCI
formats.

In the 44 pin packages, two different microprocessor
bus interfaces can be selected through an input
mode pin (IM): Non-Multiplexed or Multiplexed.
These interfaces provide compatibility with Intel/
National multiplexed and Motorola Multiplexed/Non-
Multiplexed buses. In 44 pin, the MT8986 provides a
16 x 8 switching configuration to form a 512 x 256
channel blocking matrix. Also, a flexible Stream Pair
Selection operation allows the software selection of
which pair of input and output streams can be
connected to an internal 128 x 128 matrix. See
Switching Configurations section for details.

Functional Description

A functional Block Diagram of the MT8986 device is
shown in Figure 1. Depending on the application, the

MT8986 device receives TDM serial data at different
rates and from different number of serial streams.

Data and Connect Memories

For all data rates, the received serial data is
converted to parallel format by the serial to parallel
converters and stored sequentially in a Data
Memory. Depending on the selected operation
programmed in the IMS (Interface Mode Select)
register, the Data Memory may have up to 512 bytes
in use. The sequential addressing of the Data
Memory is performed by an internal counter which is
reset by the input 8 kHz frame pulse (FR) marking
the frame boundaries of the incoming serial data
streams.

Data to be output on the serial streams may come
from two sources: Data Memory or Connect Memory.
Locations in the Connect Memory, which is split into
HIGH and LOW parts, are associated with particular
ST-BUS output streams. When a channel is due to
be transmitted on an ST-BUS output, the data for the
channel can either be switched from an ST-BUS
input as in connection mode or it can be from the
Connect Memory Low as in message mode. Data
destined for a particular channel on the serial output
stream is read from the Data Memory or Connect
Memory Low during the previous channel time-slot.
This allows enough time for memory access and
parallel to serial conversion.

Connection and Message Modes

In connection mode, the addresses of the input
source data for all output channels are stored in the
Connect memories High (CMH) and Low (CML). The
CML and CMH are mapped so that each location
corresponds to an output channel on the output
streams. The number of source address bits in CMH
and CML to be utilized varies according to the
switching configuration selected in the IMS register.
For details on the use of the source address data
(CAB and SAB bits), see CMH and CML bit descrip-
tion (Figures 5 & 6). Once the source address bits
are programmed by the CPU, the contents of the
Data Memory at the selected address are transferred
to the parallel-to-serial converters. By having the
output channel specify the source channel through
the connect memory, the user can route the same
input channel to several output channels, allowing
broadcast facility within the switch.

In message mode the CPU writes data to the
Connect Memory Low locations corresponding to the
output link and channel number. The contents of the
Connect Memory Low are transferred directly to the
parallel-to-serial converter one channel before it is to

MT8986

2-68

be output. The Connect Memory Low data is
transmitted on to the output every frame until it is
changed by the CPU with a new data.

The features of each output channel in the MT8986
are controlled by the Connect Memory High bits.
These bits determine individual output channels to
be in message or connection mode, select
throughput delay types and enable/disable output
drivers. The Connect Memory High also provides
additional stream and channel address bits for some
configurations. In addition, the Connect Memory
High provides one bit to allow the user to control the
CSTo output in 2.048 Mb/s applications.

If an output channel is set to high-impedance, the
TDM serial stream output will be placed in high
impedance during that channel time. In addition to
the per-channel control, all channels on the TDM
outputs can be placed in high impedance by pulling
the ODE input pin LOW. This overrides the individual
per-channel programming by the Connect Memory
High bits.

The Connect Memory data is received via the
Microprocessor Interface through the data I/O lines.
The addressing of the MT8986 internal registers,
Data and Connect memories is performed through
address input pins and some bits of the device's
Control register. The higher order address bits come
from the Control register, which may be written or
read through the microprocessor interface. The
lower order address bits come directly from address
input pins. For details on the device addressing, see
Software Control and Control register bits
description (Figure 3 & Tables 5, 6 and 7).

Serial Data Interface

The master clock (CLK) can be either at 4.096 or
8.192 MHz allowing serial data link operations at
2.048, 4.096 and 8.192 Mb/s. These data rates can
be independently selected on input and output
streams allowing the MT8986 device to be used in
various speed backplanes and in rate conversion
applications. The selected data rates apply to the
inputs or the output streams. Different bit rates
among input streams or among output streams are
not allowed. Due to the I/O data rate selection
flexibility, two major operations can be selected:
Identical or Different I/O data rates.

The DMO bit (Device Main Operation) in the IMS
register is used for selecting between Identical I/O
rates or Different I/O rates. On system power-up, the
CPU should set up the DMO, the IDR (Input Data
Rate) and ODR (Output Data Rate) bits located in
the IMS register. When Identical I/O data rates are
selected by the DMO bit, the switching configuration

and the number of the device's input and output
streams can be selected through the SCB bits
(Switching Configuration Bits) in the IMS register.
See Switching Configurations section for details.

Depending on the application, the interface clock can
be selected to be twice the data rate or equal to the
data rate. This selection is performed through bit
CLKM in the IMS register. For applications where
both serial inputs and outputs are at 2.048 Mb/s (ST-
BUS or GCI format), the CLKM bit should be set
LOW enabling the interface clock to be twice the bit
rate. In applications where both inputs and outputs
are at 4.096 or 8.192 Mb/s, CLKM should be set
HIGH enabling the interface clock to be equal to the
bit rate. In applications where inputs and outputs are
at different rates, the CLKM bit has no effect.

In applications with serial links at 2.048 Mb/s (see
Figures 16 to 19), the input 8 kHz frame pulse can be
in either ST-BUS or GCI format. The MT8986 device
automatically detects the presence of an input frame
pulse and identifies what type of backplane is
present on the serial interface. Upon determining the
interface connected to the serial port, the internal
timing unit establishes the appropriate transmit and
sampling edges. In ST-BUS format, every second
falling edge of the 4.096 MHz clock marks a bit
boundary and the input data is clocked in by the
rising edge, three quarters of the way into the bit cell.
In GCI format, every second rising edge of the 4.096
MHz clock marks the bit boundary while data
sampling is performed during the falling edge, at
three quarters of the bit boundaries.

For identical I/O rates at 4.096 and 8.192 Mb/s (see
Figure 20), the clock and interface data rates are
equal. The bit transmit and sampling edges vary
according to the applied frame pulse polarity. For
example, if the FR pulse polarity is positive, the bit
transmit operation is done on every rising edge of
CLK and the bit sampling on every falling edge. If
the FR pulse polarity is negative, these edges are
inverted. For different I/O rates, the MT8986 side
operating at 2.048 Mb/s data rate will comply with
ST-BUS or GCI interfaces for transmit and sampling
procedures. The MT8986 side operating at 4.096 or
8.192 Mb/s behaves according to the frame pulse
polarity applied. See Figures 22 to 25.

Switching Configurations

Switching configurations are determined basically by
the interface rates selected at the serial inputs and
outputs. To specify the switching configuration
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

MT8986

2-69

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).

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 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.

If 8 x 8 switching configuration is selected, a 256 x
256 channel non-blocking switching matrix is
available. In this configuration, the MT8986 device is
configured with 8 input and 8 output data streams
with 32 64 Kbit/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. This configuration is
available in both the 40 and 44 pin packages.

In 16 x 8 switching configuration, a 512 x 256
channel blocking switch matrix is available. This
configuration is only provided in the 44 pin package
and when the CPU interface is configured in
multiplexed bus mode. The device clock in this
application is 4.096 MHz, ST-BUS or GCI
compatible. This configuration only provides variable
throughput delay.

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

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. This configuration is only provided in the
44 pin packages.

In case of nibble switching, 4-bit wide 32 kb/s data
channels can be switched within the device. In this
case, every serial stream is run at 2.048 Mb/s and
transports 64 nibbles per frame. When Nibble
Switching is selected at SCB bits, the MT8986
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.

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 MT8986. Only variable
throughput delay mode is provided.

In case of 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 20 shows the timing for 4.096 Mb/s operation.

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 20 shows the timing for
8.192 Mb/s operation.

Table 1 summarizes the MT8986 switching
configurations for identical I/O data rates.

MT8986

2-70

Table 1. Switching Configurations for Identical Input and Output Data Rates

* - only in the 44 pin packages

Serial

Interface

Data Rate

Interface

Clock

required at

CLK Pin

(MHz)

Number of

Input x
Output

Streams

Matrix

Channel

Capacity

Input/Output

Streams Used

Variable/

Constant

throughput

Delay

Selection

2 Mb/s

4.096

8x8

256x256 Non-Blocking

STi0-7/STo0-7

Yes

2 Mb/s

4.096

16x8

512x256 Blocking

STi0-15/STo0-7

2 Mb/s

4.096

10x10

128x128 Non-Blocking

(only 4 input x 4-output

can be selected)

STi0-9/STo0-9

Yes

Nibble

Switching

(2 Mb/s)

4.096

8x4

512x256 Nibbles

STi0-7/STo0-3

4 Mb/s

4.096

8x4

512x256 Blocking

STi0-7/STo0-3

4 Mb/s

4.096

4x4

256x256 Non-Blocking

STi0-3/STo0-3

Yes

8 Mb/s

8.192

2x2

256x256 Non-Blocking

STi0-1/STo0-1

Yes

Different Input/Output Data Rates

When Different I/O rate is selected by the DMO bit,
the input and output data rates should be selected at
the IDR and ODR bits, respectively. The Switching
Configuration Bits (SCB) are ignored with this
operation. This selection allows the user to multiplex
conventional 2.048 Mb/s serial streams into two
higher rates and vice-versa. In addition to the rate
conversion itself, the MT8986 allows for a complete
256 x 256 channel non-blocking switch at different
rates. In this operation, the per-channel variable/
constant throughput delay selection is provided.

Depending on which data rates are programmed for
input and output streams, the number of data
streams used on the input and output as well as the
serial interface clock (CLK input pin) is different.
Once the CPU defines the data rates at the IDR and
ODR bits, the MT8986 automatically configures itself
with the appropriate number of input and output
streams for the desired operation. Table 2
summarizes the four options available when MT8986
is used with different I/O rates. Figures 22 to 25
show the timing for each of the four modes shown in
Table 2.

Input Frame Offset Selection

When 4.096 or 8.192 Mb/s serial interfaces are
selected, the MT8986 device provides a feature
called Input Frame Offset allowing the user to
compensate for the varying delays at the incoming
serial inputs while building large switch matrices.
Usually, different delays occur on the digital
backplanes causing the data and frame
synchronization signals to be skewed at the input of
the switch device. This may result in the system
frame synchronization pulse to be active at the
MT8986 FR input before the first bit of the frame is
received at the serial inputs.

When the input frame offset is enabled, an "internal
delay" of up to four clock periods is added to the
actual data input sampling, providing the MT8986
serial timing unit a new input frame reference. An
internal virtual frame is created which is aligned with
the framing of the actual serial data coming in at the
serial inputs and not with the FR frame pulse input.
In this operation, the transmission of the output
frame on the serial links is still aligned to the frame
pulse input signal (FR).

The selection of the data input sampling delay is
defined by the CPU in the Frame Input Offset

Table 2. Switching Configurations for Different I/O Data Rates

Input and

Output

Data Rates

Interface

Clock

required at

CLK Pin

(MHz)

Number

of Input

x Output

Streams

Matrix

Channel Capacity

Input/Output

Streams Used

Variable/

Constant

throughput

Delay

Selection

2 Mb/s to 4 Mb/s

4.096

8x4

256x256 Non-Blocking

STi0-7/STo0-3

Yes

2 Mb/s to 8 Mb/s

8.192

8x2

256x256 Non-Blocking

STi0-7/STo0-1

Yes

4 Mb/s to 2 Mb/s

4.096

4x8

256x256 Non-Blocking

STi0-3/STo0-7

Yes

8 Mb/s to 2 Mb/s

8.192

2x8

256x256 Non-Blocking

STi0-1/STo0-7

Yes

MT8986

2-71

Register (FIO). If this function is not required in the
user's applications, the FIO register should be set up
during system initialization to a state where offset
functions are disabled.

Delay Through the MT8986

The switching of information from the input serial
streams to the output serial streams results in a
delay. Depending on the type of information to be
switched, the MT8986 device can be programmed to
perform time-slot interchange functions with different
throughput delay capabilities on a per-channel basis.
For voice applications, variable throughput delay can
be selected ensuring minimum delay between input
and output data. In wideband data applications,
constant throughput delay can be selected
maintaining the frame integrity of the information
through the switch.

The delay through the MT8986 device varies
according to the type of throughput delay selected in
the V/C bit of the connect memory high.

Variable Throughput Delay Mode (V/C bit = 0)

Identical I/O Data Rates

The delay in this mode is dependent on the
combination of source and destination channels and

it is independent of the input and output streams.
The minimum delay achievable in the MT8986
depends on the data rate selected for the serial
streams. For instance, for 2.048 Mb/s the minimum
delay achieved corresponds to three time-slots. For
4.096 Mb/s it corresponds to five time-slots while for
8.192 Mb/s it is nine time-slots. Switching
configurations with input and output channels that
provides more than its corresponding minimum
throughput delay, will have a throughput delay equal
to the difference between the output and input
channels; i.e., the throughput delay will be less than
one frame period. Table 3a shows the MT8986
throughput delay for each data rate operation.

Different I/O Data Rates

Except for 2 Mb/s to 4 Mb/s and 2 Mb/s to 8 Mb/s
rate conversion operations, the throughput delay in
the MT8986 may vary according to the output stream
used for switching.

Table 3b explains the worst case conditions for the
throughput delay when different I/O data rate
switching configurations are used.

Constant Throughput Delay mode (V/C bit = 1)

In this mode frame sequence integrity is maintained
in both Identical and Different I/O Data Rate

Table 3a. Variable Throughput Delay Values for Identical I/O Rate Applications

n= input channel, t.s. = time-slot

Table 3b. Min/Max Throughput Delay Values for Different I/O Rate Applications

Notes: dmin and dmax are measured in time-slots and at the point in time when the output channel is completely shifted out.

t.s. = time-slot

fr. = 125 µs frame
2 Mb/s t.s. = 3.9 µs

4 Mb/s t.s. = 1.95 µs
8 Mb/s t.s. = 0.975 µs

Input Rate

Output Channel (# m)

m < n

m=n, n+1, n+2

m= n+3, n+4

m=n+5, .. n+8

m > n+8

2.048 Mb/s

32-(n-m) t.s.

m-n + 32 t.s.

m-n t.s.

4.096 Mb/s

64-(n-m) t.s.

m-n + 64 t.s.

m-n+64 t.s.

m-n t.s.

8.192 Mb/s

128-(n-m) t.s.

m-n + 128 t.s.

m-n+128 t.s.

m-n t.s.

I/O Data Rate

Configuration

Output Stream Used

0, 1

2, 3

4, 5

6, 7

2 Mb/s to 4 Mb/s

dmin=5x 4Mb/s t.s.
dmax=1 fr.+(4x 4Mb/s t.s.)

2 Mb/s to 8 Mb/s

dmin=9x 8Mb/s t.s.
dmax=1 fr.+(8x 8Mb/s t.s.)

4 Mb/s to 2 Mb/s

dmin=3x 2Mb/s t.s.
dmax=1 fr.+(2x 2Mb/s t.s.)

dmin=(2x 2Mb/s t.s.)+(1x 4Mb/s t.s.)
dmax=1 fr.+(1x 2Mb/s t.s.)+(1x 4Mb/s t.s.)

8 Mb/s to 2 Mb/s

dmin=3x 2Mb/s t.s.
dmax=1 fr.+(2x 2Mb/s

t.s.)

dmin=(2x 2Mb/s t.s.)+

(3x 8Mb/s t.s.)

dmax=1 fr.+(1x 2Mb/s

t.s.)+(3x 8Mb/s t.s.)

dmin=(2x 2Mb/s t.s.)+

(2x 8Mb/s t.s.)

dmax=1 fr.+(1x 2Mb/s

t.s.)+(2x 8Mb/s t.s.)

dmin=(2x 2Mb/s t.s.)+

(1x 8Mb/s t.s.)

dmax=1 fr.+(1x 2Mb/s

t.s.)+(1x 8Mb/s t.s.)

MT8986

2-72

Table 4. Constant Throughput Delay values

Data Rate

Throughput Delay (d)

2.048 Mb/s

d=[32 + (32 - IN) + (OUT - 1)]; (expressed in # time-slots)

2.048 Mb/s time-slot: 3.9µs
IN: input time-slot (from 1 to 32)

OUT: output time-slot (from 1 to 32)

4.096 Mb/s

d=[64 + (64 - IN) + (OUT - 1)]; (expressed in # time-slots)

4.096 Mb/s time-slot: 1.95 µs

IN: input time-slot (from 1 to 64)
OUT: output time-slot (from 1 to 64)

8.192 Mb/s

d=[128 + (128 - IN) + (OUT - 1)]; (expressed in # time-slots)

8.192 Mb/s time-slot: 0.975 µs
IN: input time-slot (from 1 to 128)
OUT: output time-slot (from 1 to 128)

operations by making use of a multiple Data-Memory
buffer technique. The input channels written in any of
the buffers during frame N will be read out during
frame N+2. In applications at 2.048 Mb/s for
instance, the minimum throughput delay achievable
in constant delay mode will be 32 time-slots; for
example, when input time-slot 32 (channel 31) is
switched to output time-slot 1 (channel 0). Likewise,
the maximum delay is achieved when the first time
slot in a frame (channel 0) is switched to the last
time-slot in the frame (channel 31), resulting in 94
time-slots of delay.

To summarize, any input time-slot from input frame N
will always be switched to the destination time-slot
on output frame N+2. Table 4 describes the MT8986
constant throughput delay values for different data
rates.

Microprocessor Port

The non-multiplexed bus interface provided by the
MT8986 device is identical to that provided in
MT8980 Digital Switch device. In addition to the non-
multiplexed bus, the MT8986 device provides an
enhanced microprocessor interface with multiplexed
bus structure compatible to both Motorola and Intel
buses. The multiplexed bus structure is available
only in the 44 pin packages and it is selected by the
CPU Interface Mode (IM) input pin.

If IM input pin is not connected (left open) or
grounded, the MT8986 parallel port assumes its
default Motorola non-multiplexed bus mode identical
to that of MT8980. If IM input is connected HIGH, the
internal parallel microport provides compatibility to
MOTEL interface allowing direct connection to Intel,
National and Motorola CPUs.

The MOTEL circuit (MOtorola and InTEL compatible
bus) automatically identifies the type of CPU Bus
connected to the MT8986 device. This circuit uses

the level of the DS/RD input pin at the rising edge of
the AS/ALE to identify the appropriate bus timing
connected to the MT8986. If DS/RD is LOW at the
rising edge of AS/ALE then Motorola bus timing is
selected. If DS/RD is HIGH at the rising edge of AS/
ALE, then Intel bus timing is selected.

When MT8986 parallel port is operating in Motorola,
National or Intel multiplexed bus interfaces, the
signals available for controlling the device are: AD0-
AD7 (Data and Address), ALE/AS (Address Latch
Enable/Address Strobe), DS/RD (Data Strobe/
Read), R/W\WR (Read/Write\Write), CS (Chip
Select) and DTA (Data Acknowledgement). In
Motorola non-multiplexed bus, the interface control
signals are: data bus (AD0-AD7), six address input
lines (A0-A5) and four control lines (CS , DS, R/W
and DTA). See Figures 26 to 28 for each CPU
interface timing.

The MT8986 parallel microport provides the access
to the IMS, Control registers, the Connection
Memory High, the Connection Memory Low and the
Data Memory. All locations can be read or written
except for the data memory which can be read only.

Software Control

The address bus on the microprocessor interface
selects the internal registers and memories of the
MT8986. If the A5 address input is LOW, then the
MT8986 Internal Control, Interface Mode, Stream
Pair Selection and Frame Input Offset registers are
addressed by the A4 to A0 bits according to Table 5.
If A5 input is HIGH, then the remaining address input
lines are used to select memory subsections of up to
128 locations corresponding to the maximum
number of channels per input or output stream. The
address input lines and the Stream Address bits
(STA) of the Control register give the user the
capability of accessing all sections of the MT8986
Data and Connect memories.

MT8986

2-73

The Control and Interface Mode Selection registers
together control all the major functions of the device.
The Interface Mode Select register should be set up
during system power-up to establish the desired
switching configuration as explained in the Serial
Interface and Switching Configurations sections.

The Control register is dynamically used by the CPU
to control switching operations in the MT8986. The
Control register selects the device's internal
memories and its subsections to specify the input
and output channels selected for switching
procedures.

The data in the Control register consists of Split
memory and Message mode bits, Memory select and
Stream Address bits. The memory select bits allow
the Connect Memory HIGH or LOW or the Data
Memory to be chosen, and the Stream Address bits
define an internal memory subsections
corresponding to input or output ST-BUS streams.

Bit 7 (Slip Memory) of the Control register allows split
memory operation whereby reads are from the Data
memory and writes are to the Connect Memory
LOW.

The Message Enable bit (bit 6) places every output
channel on every output stream in message mode;
i.e., the contents of the Connect Memory LOW
(CML) are output on the ST-BUS output streams
once every frame unless the ODE input pin is LOW.
If ME bit is HIGH, then the MT8986 behaves as if bits
2 (Message Channel) and 0 (Output Enable) of every

Connect Memory HIGH (CMH) locations were set to
HIGH, regardless of the actual value. If ME bit is
LOW, then bit 2 and 0 of each Connect Memory
HIGH location function normally. In this case, if bit 2
of the CMH is HIGH, the associated ST-BUS output
channel is in Message mode. If bit 2 of the CMH is
LOW, then the contents of the SAB and CAB bits of
the CMH and CML define the source information
(stream and channel) of the time-slot that is to be
switched to an output.

If the ODE input pin is LOW, then all serial outputs
are high-impedance. If ODE is HIGH, then bit 0
(Output Enable) of the CMH location enables (if
HIGH) or disables (if LOW) the output drivers for the
corresponding individual ST-BUS output stream and
channel.

The contents of bit 1 (CSTo) of each Connection
Memory High location is output on CSTo pin once
every frame. The CSTo pin is a 2048 Mbit/s output
which carries 256 bits. If CSTo bit is set HIGH, the
corresponding bit on CSTo output is transmitted
HIGH. If CSTo bit is LOW, the corresponding bit on
the CSTo output is transmitted LOW. The contents of
the 256 CSTo bits of the CMH are transmitted
sequentially on to the CSTo output pin and are
synchronous to the 2.048 Mb/s ST-BUS streams. To
allow for delay in any external control circuitry the
contents of the CSTo bit is output one channel before
the corresponding channel on the ST-BUS streams.
For example, the contents of CSTo bit in position 0
(ST0, CH0) of the CMH, is transmitted
synchronously with ST-BUS channel 31, bit 7. The
contents of CSTo bit in position 32 (ST1, CH0) of the

Table 5. Address Memory Map

channels 0 to 31 are used in 2.048 Mb/s (8 x 8, 16 x 8 and 10 x 10)

**:

channels 0 to 63 are used in 4.096 Mb/s (Nibble Switching, 4 x 4, 8 x 4 or Different I/O rates)

***: channels 0 to 127 are used in 8.192 Mb/s (2 x 2 or Different I/O rates)

Location

Control Register

Interface Mode Select Register

Stream Pair Select Register

Frame Input Offset Register

Channel 0*

·
·

1
1
1
1

·
·

Channel 1*

·
·

Channel 31*

Channel 32**

·
·

1
1
1
1

·
·

Channel 33**

·
·

Channel 63**

·
·

1
1
1
1

·
·

Channel 64***

·
·

Channel 127***

MT8986

2-74

CMH is transmitted during ST-BUS channel 31 bit
6. For more detailed description of the CSTo
operation, see section 6 of Application Note MSAN-
123.

The Bit V/C (Variable/Constant Delay) of each
Connect Memory High location allows the per-
channel selection between Variable and Constant
throughput delay modes.

Initialization of the MT8986

On initialization or power up, the contents of the
Connection Memory High can be in any state. This
is a potentially hazardous condition when multiple
MT8986 ST-BUS outputs are tied together to form
matrices, as these outputs may conflict. The ODE
pin should be held low on power up to keep all
outputs in the high impedance condition.

During the microprocessor initialization routine, the
microprocessor should program the desired active
paths through the matrices, and put all other
channels into the high impedance state. Care
should be taken that no two ST-BUS outputs drive
the bus simultaneously. When this process is
complete, the microprocessor controlling the
matrices can bring the ODE signal high to relinquish
high impedance state control to the CMH

0s.

MT8986

2-75

Control Register - Read/Write

Figure 3 - Control Register Description

BIT

NAME

DESCRIPTION

Split Memory. When 1, all subsequent reads are from the Data Memory and writes are to
the Connection Memory Low, except when the Control Register is accessed again. When
0, the Memory Select bits specify the memory for subsequent operations. In either case,
the Stream Address Bits select the subsection of the memory which is made available.

Message Enable. When 1, the contents of the Connection Memory Low are output on the
Serial Output streams except when in High Impedance as set by the ODE input. When 0,
the Connection Memory bits for each channel determine what is output.

STA3

Stream Address Bit 3. This bit is used in the 44 pin packages when 16 x 8 switching
configuration is selected. It is used with STA2-0 to select one of the 16 input data streams
whenever the Data Memory is to be read. The programming of this bit has no effect in
other switching configurations.

4-3

MS1-0

Memory Select Bits. The memory select bits operate as follows:

0-0 - Not to be used

0-1 - Data Memory (read only from the CPU)

1-0 - Connection Memory Low

1-1 - Connection Memory High

2-0

STA2-0

The number expressed in binary notation on these bits refers to the input or output ST-
BUS stream which corresponds to the subsection of memory made accessible for
subsequent operations.

The use of these bits depends on the switching configuration as well as the device's main
operation defined by the DMO bit of the Interface Mode Selection register. Tables 6 and 7
show the utilization of these bits according to the device's main operation.

STA3

MS1

MS0

STA2

STA1

STA0

MT8986

2-76

Table 6. Use of STA Bits for Identical I/O Data Rate Operation

* - only in the 44 pin packages.
** - for Data Memory Read operations A0 is not required since two nibbles are provided per read access.

Table 7. Use of STA Bits for Different I/O Data Rate Operation

Note: In rate conversion applications, Data Memory subsections have different sizes than Connection Memory subsections. This

implies that different address inputs are used to select individual positions within the subsections for each type of memory.

Identical

I/O

Rate

# of Input x

Output

Streams

STA bits used to

select subsections

of the Data

Memory

STA bits used to

select

subsections of the

Connection

Memory

Input Address pins used to

select individual

Connection and Data

Memory positions within the

selected subsection

2 Mb/s

8x8

STA2, STA1, STA0

A4, A3, A2, A1, A0

2 Mb/s *

4x4 *

STA1, STA0

A4, A3, A2, A1, A0

2 Mb/s *

16x8 *

STA3, STA2, STA1,
STA0

STA2, STA1, STA0

A4, A3, A2, A1, A0

4 Mb/s

4x4

STA1, STA0

A6, A4, A3, A2, A1, A0

4 Mb/s

8x4

STA2, STA1, STA0

STA1, STA0

A6, A4, A3, A2, A1, A0

8 Mb/s

2x2

STA0

A7, A6, A4, A3, A2, A1, A0

Nibble Switch

(2 Mb/s)

8x4

STA2, STA1, STA0

STA1, STA0

A6, A4, A3, A2, A1, A0 **

Different

I/O

Rate

Input x
Output

Streams

Config.

STA bits used

to select

Data

Memory

subsections

STA bits used

to select

Connection

Memory

subsections

Input Address pins used

to access individual

Data Memory

positions within the

selected subsection

Input Address pins used

to access individual

Connection Memory

positions within the

selected subsection

2 Mb/s to

4 Mb/s

8x4

STA2, STA1,
STA0

STA1, STA0

A4, A3, A2, A1, A0

A6,

A4, A3, A2, A1, A0

2 Mb/s to

8 Mb/s

8x2

STA2, STA1,
STA0

STA0

A4, A3, A2, A1, A0

A7, A6, A4, A3, A2, A1,
A0

4 Mb/s to

2 Mb/s

4x8

STA1, STA0

STA2, STA1,
STA0

A6,

A4, A3, A2, A1, A0

8 Mb/s to

2 Mb/s

2x8

STA0

STA2, STA1,
STA0

A7, A6, A4, A3, A2, A1,
A0

A4, A3, A2, A1, A0

MT8986

2-77

Interface Mode Selection Register - Read/Write

Figure 4 - IMS Register Description

BIT

NAME

DESCRIPTION

DMO

Device Main Operation. This bit is used by the CPU to define one of the two main
operations of the MT8986 device. If this bit is LOW, the MT8986 is configured for
identical I/O data rates. For this operation, the user should also specify the switching
configuration through the SCB bits.

If this bit is HIGH, the MT8986 device is configured in Different I/O data rate. This allows
combinations of input and output data rates as shown in Table 2. The SCB bits have no
effect in this application and the device is in Non-Blocking switch configuration with a 256
x 256 channel capacity.

6-5

IDR1-0

Input Data Rate Selection. These two bits select three different data rates for the inputs
of the MT8986. In the case of identical I/O rates (DMO bit = 0), these bits also determine
the serial output data rate.

IDR1

IDR0

Input Rate

2.048 Mb/s

4.096 Mb/s

8.192 Mb/s

reserved

4-3

ODR1-0

Output Data Rate Selection. These bits are only used when Different I/O rates are
selected (DMO bit=1). These two bits select three different data rates for the serial
outputs of the MT8986. These bits are ignored if DMO bit = 0.

ODR1

ODR0

Output Rate

2.048 Mb/s

4.096 Mb/s

8.192 Mb/s

reserved

2-1

SCB1-0

Switching Configuration Bits 1-0. These bits should only be used when DMO is set
LOW. The use of these bits to select the switching configuration of the MT8986 device is
described in Table 8.

CLKM

Clock Mode. This bit is only used when the MT8986 device is set to operate in identical
I/O data rates. When set High, this bit selects the interface clock to be equal to the bit
rate. If Low, this bit selects the interface clock to be twice the bit rate.
For Different I/O data rate applications, this bit is ignored.

DMO

IDR1

IDR0

ODR1

ODR0

SCB1

SCB0

CLKM

MT8986

2-79

Connection Memory High - Read/Write

Figure 5 - Connection Memory High (CMH) Bits

x=Don't care

BIT

NAME

DESCRIPTION

V/C

Variable/Constant Throughput Delay Mode. This bit is used to select between Variable
(LOW) and Constant Delay (HIGH) modes in a per-channel basis. Tables 1 and 2
describe the switching configurations that have this function. In the modes where this
function is not available, this bit has not effect.

SAB3

Source Stream Address bit 3. This bit is used along with bits SAB0-2 in CML to select
up to 16 different source streams for the connection. Depending on the state of DMO bit
and the switching configuration enabled, not all SAB3-0 bits have to be used.
See Tables 9 and 10 for details on the utilization of the SAB bits.

4-3

CAB6-5

Source Channel Address bits 5 and 6. These two bits are used together with bits
CAB0-4 in Connect Memory Low to select up 128 different source channels for the
connection. Depending on the data rate used in the input/output streams, 5, 6 or all 7
CAB bits can be used respectively, to select 32, 64 or 128 different channels.
See Tables 9 and 10 for details on the utilization of the CAB bits.

Message Channel. When 1, the contents of the corresponding location in Connection
Memory Low are output on the corresponding channel and stream. When 0, the contents
of the programmed location in Connection Memory Low act as an address for the Data
Memory and so determine the source of the connection to the location's channel and
stream.

CSTo

CSTo Bit. This bit is only available in 2.048 Mb/s applications. It drives a bit time on the
CSTo output pin.

Output Enable. This bit enables the output drivers on a per-channel basis. This allows
individual channels on individual streams to be made high-impedance, allowing switch
matrices to be constructed. A HIGH enables the driver and a LOW disables it.

V/C

SAB3

CAB6

CAB5

CSTo

(CM high bits)

MT8986

2-80

Connection Memory Low - Read/Write

Figure 6 - Connection Memory Low (CML) Bits

Table 9. CAB and SAB Bits Programming for Identical I/O Rate Applications

* - only in 44 pin package

Table 10. CAB and SAB Bits Programming for Different I/O Rate Applications

BIT

NAME

DESCRIPTION

7-5

SAB2-0*

Source Stream Address bits. These three bits are used together with SAB3 in CMH to

select up to 16 different source streams for the connection. Depending on the switching
configuration and the data rate selected in the application, 1, 2, 3 or all 4 SAB bits can be
used. See Tables 9 and 10 for details.

4-0

CAB4-0*

Source Channel Address bits 0-4. These five bits are used together with CAB5-6 in

CMH to select up 128 different source channels for the connection. Depending on the
switching configuration and the data rate used in the application, 5, 6 or all 7 CAB bits
can be used to select respectively 32, 64 or 128 different channels.
See Tables 9 and 10 for details.

If bit two (MC) of the corresponding Connection High locations is 1, or if bit 6 of the Control Register is 1, then these entire eight bits are output
on the corresponding output channel and stream associated with this location. Otherwise, the bits are used as indicated to define the source
of the connection which is output on the channel and stream associated with this location.

Identical

I/O

Rate

# of Input x

Output

Streams

CAB bits used to determine the source

channel for the connection

SAB bits used to

determine the source

stream for the

connection

2 Mb/s

8x8

CAB4 to CAB0 (32 channel/inp. stream)

SAB2, SAB1, SAB0

2 Mb/s *

4x4 *

CAB4 to CAB0 (32 channel/inp. stream)

SAB2, SAB1

2 Mb/s *

16x8 *

CAB4 to CAB0 (32 channel/inp. stream)

SAB3, SAB2, SAB1, SAB0

4 Mb/s

4x4

CAB5 to CAB0 (64 channel/inp. stream)

SAB2, SAB1

4 Mb/s

8x4

CAB5 to CAB0 (64 channel/inp. stream)

SAB2, SAB1, SAB0

8 Mb/s

2x2

CAB6 to CAB0 (128 channel/inp. stream)

SAB2

Nibble Switch

(2 Mb/s)

8x4

CAB5 to CAB0 (64 nibble/inp. stream)

SAB2, SAB1, SAB0

Different

I/O

Rate

# of Input x

Output Streams

CAB bits used to determine the source

channel for the connection

SAB bits used to

determine the source

stream for the

connection

2 Mb/s to 4 Mb/s

8x4

CAB4 to CAB0 (32 channel/inp. stream)

SAB2, SAB1, SAB0

2 Mb/s to 8 Mb/s

8x2

CAB4 to CAB0 (32 channel/inp. stream)

SAB2, SAB1, SAB0

4 Mb/s to 2 Mb/s

4x8

CAB5 to CAB0 (64 channel/inp. stream)

SAB2, SAB1

8 Mb/s to 2 Mb/s

2x8

CAB6 to CAB0 (128 channel/inp. stream)

SAB2

SAB2

SAB1

SAB0

CAB4

CAB3

CAB2

CAB1

CAB0

(CM low bits)

MT8986

2-81

Stream Pair Selection Register - Read/Write (ONLY PROVIDED IN THE 44 PIN PACKAGES)

Figure 7 - Stream Pair Selection (SPS) Register

x=Don't care

Frame Input Offset Register - Read/Write

Figure 8 - Frame Input Offset (FIO) Register

x=Don't care

BIT

NAME

DESCRIPTION

5-3

SPA2-0

Stream Pair A selection. These three bits define which pair of streams are going to be
connected to the switch matrix, together with the permanently connected streams
STi0-1 / STo0-1.

SPA2

SPA1

SPA0

Stream Pair A Connected

STi2 / STo2

STi3 / STo3

STi4 / STo4

STi5 / STo5

STi6 / STo6

STi7 / STo7

STi8 / STo8

STi9 / STo9

2-0

SPB2-0

Stream Pair B selection. These three bits define which pair of streams are going to be
connected to the switch matrix, together with the permanently connected streams
STi0-1 / STo0-1.

SPB2

SPB1

SPB0

Stream Pair B Connected

STi2 / STo2

STi3 / STo3

STi4 / STo4

STi5 / STo5

STi6 / STo6

STi7 / STo7

STi8 / STo8

STi9 / STo9

These bits are only used when the Switching Configuration bits enable stream pair selection capability (SCB 1-0 =10) and the Input Data Rate
Selection bits enable 2 Mb/s operation (IDR-0 = 00). In all other modes, the contents of this register are ignored.

BIT

NAME

DESCRIPTION

7-5

OFB2-0

Offset Bits 2-0. These three bits define the time it takes the Serial Interface receiver to
recognize and store the first bit of the serial input streams; i.e., to start assuming a new
internal frame. The input frame offset can be selected to be up to 4 CK clock periods from
the time when frame pulse input signal is applied to the FR input.

OFB2

OFB1

OFB0

Number of Clock Periods

Normal Operation. No bit offsetting.

Reserved

If frame input offset operation is not required, this register should be cleared by the CPU during system initialization.

SPA2

SPA1

SPA0

SPB2

SPB1

SPB0

OFB2

OFB1

OFB0

MT8986

2-82

Applications

Switch Matrix Architectures

The MT8986 is an ideal device for designs of
medium size switch matrix. For applications where
voice and grouped data channels are transported
within the same frame, the voice samples have to be
time interchanged with a minimum delay while
maintaining the integrity of grouped data. To
guarantee the integrity of grouped data during
switching and to provide a minimum delay for voice
connections, the MT8986 provides the per-channel
selection between variable and constant throughput

delay. This can be selected by the V/C bit of the
Connection Memory High locations.

Different connectivities at different data rates can be
built to accommodate Non-Blocking matrices of up to
512 channels while maintaining the per channel
selection of the device's throughput delay. Some
examples of such Non-Blocking configurations are
given in Figures 9 to 11.

For applications where voice and data samples are
encoded into individual 64 kb/s time-slots on an
8kHz frame basis, the switch matrix can operate with
time interchange procedures where only variable

Figure 9 - 512-Channel Switch with Serial Streams at 2.048 Mb/s

Figure 10 - 256-Channel Switch with Rate Conversion between 2.048 and 4.096 Mb/s

Figure 11 - 256-Channel Switch with Rate Conversion between 2.048 and 8.192 Mb/s

MT8986

OUT

8 Streams
@ 2.048 Mb/s

MT8986

8 Streams
@ 2.048 Mb/s

MT8986

4 Streams

@ 4.096 Mb/s

STi0

·
·

STi7

STo0

·
·

STo7

STo0

STo1

STo2

STo3

STi0

STi1

STi2

STi3

8 Streams
@ 2.048 Mb/s

OUT

MT8986

8 Streams
@ 2.048 Mb/s

MT8986

2 Streams

@ 8.192 Mb/s

STi0

STi7

STo0

STo7

STo0

STo1

STi0

STi1

8 Streams
@ 2.048 Mb/s

OUT

MT8986

2-83

throughput delay is guaranteed. For such
applications, the MT8986 device allows cost
effective implementations of Non-Blocking matrices
ranging up to 1024 channels. Figures 12 and 13
show the block diagram of implementations with
Non-Blocking capacities of 512 and 1024-channel,
respectively.

Interfacing MT8986 with 8051

The Intel 8051 is a very cost effective solution for
many applications that do not require a large CPU
interaction and processing overhead. However, in
applications where 8051 is connected to peripherals
operating on a synchronous 8 kHz time-base like the
MT8986, some connectivity issues have to be
addressed. The MT8986 may hold the CPU read/
write cycle due to internal contention between the
MT8986 microport and the internal serial to parallel

and parallel to serial converters. Since the 8051
family of CPUs do not provide Data Ready type of
inputs, some external logic and software
intervention have to be provided between the
MT8986 and the 8051 microcontrollers to allow read/
write operation. The external logic described in
Figure 14 is a block diagram of a logical connection
between MT8986 and 8051. Its main function is to
store the 8051 data during a write and the MT8986
data during a read.

For a write, MT8986 address is latched by the
internal address latch on the falling edge of the ALE
input. Whenever a read or write operation is done to
the MT8986 device, the address decoded signal
(MTA) is used to latch or "freeze" the state of RD,
WR, and the ALE signals, until the data acknow-
ledge output signal is provided by the MT8986
device, releasing the latches for a new read/write
cycle. Latch U5 is used to hold the 8051 data for a
write until the CPU is ready to accept it (when DTA

Figure 12 - 512-Channel Non-Blocking Switch Matrix with Serial Streams at 2.048 or 4.096 Mb/s

Figure 13 - 1024-Channel Non-Blocking Switch Matrix with Serial Streams at 2.048 Mb/s

OUT

16 Streams

@2.048 Mb/s

8 Streams

@2.048 Mb/s

8 Streams

@2.048 Mb/s

MT8986

512 x 256

OUT

8 Streams

@4.096 Mb/s

4 Streams

@4.096 Mb/s

4 Streams

@4.096 Mb/s

MT8986

512 x 256

16 Streams

@2.048 Mb/s

16 Streams

@2.048 Mb/s

MT8986

512 x 256

MT8986

512 x 256

MT8986

512 x 256

MT8986

512 x 256

MT8986

512 x 256

MT8986

512 x 256

MT8986

512 x 256

MT8986

512 x 256

8 Streams

@2.048 Mb/s

8 Streams

@2.048 Mb/s

8 Streams

@2.048 Mb/s

8 Streams

@2.048 Mb/s

OUT

MT8986

2-85

* Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.

Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.

Figure 15 - Output Test Load

Absolute Maximum Ratings*

Parameter

Symbol

Min

Max

Units

- V

-0.3

Voltage on Digital Inputs

-0.3

+0.3

Voltage on Digital Outputs

-0.3

+0.3

Current at Digital Outputs

Storage Temperature

-65

+150

°C

Package Power Dissipation

Recommended Operating Conditions

- Voltages are with respect to ground (V

) unless otherwise stated.

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

Operating Temperature

-40

+85

°C

Positive Supply

4.75

5.0

5.25

Input Voltage

DC Electrical Characteristics

- Voltages are with respect to ground (V

) unless otherwise stated.

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

N
P
U

T
S

Supply Current

Outputs unloaded

Input High Voltage

2.0

Input Low Voltage

0.8

Input Leakage (input pins)
Input Leakage (I/O pins)

100

between V

and V

Input Pin Capacitance

T
P

T
S

Output High Voltage

2.4

= 10 mA

Output High Current

Sourcing. V

=2.4V

Output Low Voltage

0.4

= 5 mA

Output Low Current

Sinking. V

= 0.4V

High Impedance Leakage

between V

and V

Output Pin Capacitance

Output

Pin

Test Point

S1 is open circuit except

when testing output levels
or high impedance states.

S2 is switched to V

when testing output

levels or high impedance
states.

MT8986

2-86

Timing is over recommended temperature & power supply voltages (V

=5V±5%, V

=0V, T

=40 to 85°C).

Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.

Figure 16 - ST-BUS Timing (CLKM bit=0)

AC Electrical Characteristics

ST-BUS Timing (2.048 Mb/s)

Voltages are with respect to ground (VSS) unless otherwise stated.

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

Frame Pulse width

FRW

244

Frame Pulse setup time

FRS

190

Frame Pulse hold time

FRH

190

STo delay Active to Active

DAA

100

=150 pF

STi setup time

STi hold time

Clock period

CLK

190

244

300

CK Input Low

122

150

CK Input High

122

150

Clock Rise/Fall Time

2.0V

0.8V

STi

FRW

CLK

FRS

FRH

Ch. 31
Bit 0

Ch. 0
Bit 7

Ch. 0
Bit 6

Ch. 31
Bit 0

Ch. 0
Bit 7

Ch. 0
Bit 6

Ch.0
Bit 5

Ch. 0
Bit 5

DAA

2.0V

0.8V

2.0V

0.8V

2.0V

0.8V

STo

STi

MT8986

2-87

Timing is over recommended temperature & power supply voltages (V

=5V±5%, V

=0V, T

=40 to 85°C).

Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.

Figure 17 - GCI Timing (CLKM bit=0)

AC Electrical Characteristics

- GCI Timing (2.048 Mb/s)

Voltages are with respect to ground (VSS) unless otherwise stated.

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

Clock Period

150

244

300

Pulse Width

, t

122

150

Frame Width High

WFH

244

Frame Setup

FRS

190

Frame Hold

FRH

190

Data Delay/Clock Active to
Active

DAA

100

=150 pF

Serial Input Setup

Serial Input Hold

Clock Rise/Fall Time

2.0V

0.8V

STo

CLK

STi/
STo

See Detail a

Detail a

Note: bit 0 identifies the first bit of the GCI frame

DAA

WFH

FRS

FRH

STi

Ch. 0
Bit 6

Ch. 0
Bit 7

Ch. 0
Bit 4

Ch. 0
Bit 5

Ch. 31
Bit 0

2.0V

0.8V

2.0V

0.8V

2.0V

0.8V

MT8986

2-88

Timing is over recommended temperature & power supply voltages.
Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
* High Impedance is measured by pulling to the appropriate rail with R

, with timing corrected to cancel time taken to discharge C

AC Electrical Characteristics

- Serial Streams for ST-BUS and GCI Backplanes (2.048 Mb/s)

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

O
U

T
P
U
T
S

STo0/9 Delay - Active to High Z

SAZ

100

=1 K

, C

=150 pF

STo0/9 Delay - High Z to Active

SZA

100

=150 pF

Output Driver Enable Delay

OED

=1 K

, C

=150 pF

CSTo Output Delay

XCD

=150 pF

Figure 18 - Serial Outputs and External Control

CSTo

CLK

STo0
to
STo9

Bit Cell Boundary

(GCI)

(ST-BUS)

SAZ

SZA

XCD

2.0V

0.8V

2.4V

0.4V

2.4V

0.4V

2.4V

0.4V

Figure 19 - Output Driver Enable

ODE

STo0
to
STo9

2.0V

0.8V

2.4V

0.4V

OED

AC Electrical Characteristics - Serial Streams at 4.096 and 8.192 Mb/s
(refer to Figures 20-25)

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

Clock Period

4.096Mb/s
8.192Mb/s

190

110

244
122

300
150

ns
ns

Clock Pulse High

4.096Mb/s
8.192Mb/s

85
50

122

150

ns
ns

Clock Pulse Low

4.096Mb/s
8.192Mb/s

85
50

122

150

ns
ns

Frame Sync Setup

4.096Mb/s
8.192Mb/s

10
10

190

ns
ns

Frame Sync Hold

4.096Mb/s
8.192Mb/s

20
20

190

ns
ns

MT8986

2-94

, with timing corrected to cancel time taken to discharge C

AC Electrical Characteristics

- Intel/National- HPC Multiplexed Bus Mode

Voltages are with respect to ground (VSS) unless otherwise stated.

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

ALE pulse width

ALW

Address setup from ALE falling

ADS

Address hold from ALE falling

ADH

active after ALE falling

ALRD

Data setup from DTA

Low on Read

DDR

=150 pF

hold after

RD/WR

CSRW

pulse width (fast read)

setup from

CSR

Data hold after RD

DHR

=150 pF,R

=1 K

10 WR

pulse width (fast write)

11 WR delay after ALE falling

ALWR

12 CS

setup from

CSW

13 Data setup from WR (fast write)

DSW

14 Valid Data Delay on write

(slow write)

SWD

122

15 Data hold after WR

inactive

DHW

16 Acknowledgement Delay:

Reading Data Memory

Reading/Writing Conn. Memories

Writing to Control & Mode Reg.

Reading from Control & Mode Reg.

AKD

560

300/370

47
60

1220

730/800

125

ns
ns
ns
ns

=150 pF

17 Acknowledgement Hold Time

AKH

110

=150 pF,R

=1 K

MT8986

2-96

, with timing corrected to cancel time taken to discharge C

AC Electrical Characteristics

- Motorola Multiplexed Bus Mode

Voltages are with respect to ground (VSS) unless otherwise stated.

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

AS pulse width

ASW

Address setup from AS falling

ADS

Address hold from AS falling

ADH

Data setup from DTA

Low on Read

DDR

=150 pF

hold after DS falling

CSH

setup from DS rising

CSS

Data hold after write

DHW

Data setup from DS - write
(fast write)

DWS

Valid Data Delay on write
(slow write)

SWD

122

10 R/W setup from DS rising

RWS

11 R/W hold after DS falling

RWH

12 Data hold after read

DHR

=150 pF,

=1 K

13 DS delay after AS falling

DSH

14 Acknowledgement Delay:

Reading Data Memory

Reading/Writing Conn. Memories

Writing Control & Mode Regs.

Reading from Control & Mode Regs.

AKD

560

300/370

47
73

1220

730/800

125

ns
ns
ns
ns

=150 pF

15 Acknowledgement Hold Time

AKH

110

=150 pF,

=1 K

MT8986

2-97

Figure 27 - Motorola Multiplexed Bus Timing

AAAA

DTA

AD7-0
RD

R/W

ADDRESS

DATA

RWH

RWS

ASW

DSH

ADS

ADH

SWD

DWS

DHW

DHR

CSS

CSH

AKD

AKH

DDR

2.0V

0.8V

2.0V

0.8V

2.0V

0.8V

2.0V

0.8V

2.0V

0.8V

2.0V

0.8V

AAA

AAAA

AD7-0
WR

2.0V

0.8V

MT8986

2-98

Timing is over recommended temperature & power supply voltages .
Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
* High Impedance is measured by pulling to the appropriate rail with R

, with timing corrected to cancel time taken to discharge C

AC Electrical Characteristics

- Motorola Non-Multiplexed Bus Mode

Voltages are with respect to ground (VSS) unless otherwise stated.

Characteristics

Sym

Min

Typ

Max

Units

Test Conditions

Setup from DS rising

CSS

R/W Setup from DS rising

RWS

Add setup from DS rising

ADS

hold after DS falling

CSH

R/W hold after DS falling

RWH

Add hold after DS falling

ADH

Data setup from DTA

Low on Read

DDR

=150 pF

Data hold on read

DHR

=150 pF,

=1 K

Data setup on write (fast write)

DSW

10 Valid Data Delay on write

(slow write)

SWD

122

11 Data hold on write

DHW

12 Acknowledgement Delay:

Reading Data Memory

Reading/Writing Conn. Memories

Writing Control & Mode Regs.

Reading from Control & Mode Regs.

AKD

560

300/370

47
70

1220

730/800

155

ns
ns
ns
ns

=150 pF

13 Acknowledgement Hold Time

AKH

110

=150 pF,

=1 K

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: MT8986

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: MT8986