8

Commercial Temperature Range

IDT72V8985 3.3V Time Slot Interchange

Digital Switch 256 x 256

TABLE 4









 CONNECTION MEMORY HIGH

TABLE 5









 CONNECTION MEMORY LOW

TABLE 3









 CONTROL REGISTER

Bit

Name

Description

7

SM (Split Memory)

When 1, all subsequent reads are from the Data Memory and writes are to the Connection Memory, except when

the Control Register is accessed again. The Memory Select bits need to specify the memory for the operations.

6

PE (Processor Mode)

When 1, the contents of the Connection Memory LOW are output on the Serial Output streams except when in high-

impedance. When 0, the Connection Memory bits for each channel determine what is output.

5

unused

4-3

MS1-MS0

0-0 - Not to be used.

(Memory Select Bits)

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

1-0 - Connection Memory LOW

1-1 - Connection Memory is HIGH

2-0

STA2-0

The number expressed in binary notation on these bits refers to the input or output stream which corresponds to the

(Stream Address Bits)

subsection of memory made accessible for subsequent operations.

SM

PE

X

MS1

MS0

STA2

STA1

STA0

76543210

x = don't care

Bit

Name

Description

7,5,4,3

unused

6

V/C (Variable/Constant

This bit is used to select between Variable (LOW) and Constant Delay (HIGH) modes on a per-channel basis.

Throughput Delay Mode)

2

CS

When 1, the contents of the corresponding location in Connection Memory LOW are output on the location's channel

(Channel Source)

and stream. When 0, the contents of the corresponding location in Connection Memory LOW act as an address for the

Data Memory and determine the source of the connection to the location's channel and stream.

1

CCO (CCO Bit)

This bit drives a bit time on the CCO output pin.

0

OE (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.

X

V/C

XXX

CS

CCO

OE

76543210

x = don't care

Bit

Name

Description

7-5

These three bits are used to select eight source streams for the Connection.

(Source Stream Address Bits)

These five bits are used to select 32 different source channels for the Connection (the stream where the channel

(Source Channel Address Bits)

is present is defined by bits SAB2-0). Bit 4 is the most significant bit.

SAB2

SAB1

SAB0

CAB4

CAB3

CAB2

CAB1

CAB0

NOTE:

1. If bit 2 of the corresponding Connection HIGH location is 1 or bit 6 of the Control Register is 1, then these entire 8 bits are output on the 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.

76543210