MH89770 datasheet(19/36 Pages) MITEL

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4-143

Preliminary Information

MH89770

Figure 12 - Using the MH89770 in a Parallel Bus Environment

MH89770

MT8920B

(Mode 2)

D0-D7

A0-A5

R/W

MMS MS1 24/32

STo0

STi0

STo1

C4i

F0i

+5V

MT8977

E8Ko

RxD

RxB

RxA

TxB

TxA

E1.5i

C1.5i

C2i

F0i

CSTi1

CSTo

CSTi0

DSTo

DSTi

CLOCK

EXTRACTOR

MMS

High Speed

Parallel

Telecom Bus

Line

Driver

Line

Driver

OUTA

OUTB

RxT

RxR

EQU

DIP

SWITCH

MT8941

CVb

F0i

C2o

F0b

C4b

C8Kb

12.352 MHz

Osc.

16.384 MHz

Osc.

•

MT89761

Signalling and

Link Control

BUS

IACK

IRQ

DTACK

R/W

A0-A5

D0-D7

STo0

STi0

STo1

C4i

F0i

MT8920B

(Mode 1)

1.544 MHz

MT8976. The signals are combined to produce a

composite return to zero signal which is clocked into

the MT8976 at RxD.

2. Interfacing the MH89770 to a Parallel Bus

The MH89770 can be interfaced to a high speed

parallel bus or to a microprocessor using MT8920B

Parallel Access Circuit (STPA). Fig. 12 shows the

MT8977 interfaced to a parallel bus structure using

two STPA’s operating in modes 1 and 2.

The first

STPA operating

mode

2 (MMS=0,

MS1=1,

24/32=0),

routes

data

and/or

voice

information between the parallel telecom bus and the

T1 or CEPT link via DSTi and DSTo. The second

STPA, operating in mode 1 (MMS=1) provides

access from the signalling and link control bus to the

MH89770 status and control channels. All signalling

and link functions may be controlled easily through

the STPA transmit RAM’s Tx0, Tx1, while status

information is read at receive RAM Rx0. In addition,

interrupts can be set up to notify the system in case

of slips, loss of sync, alarms, violations, etc.

3. PCM/Voice Channel Bank

The D3/D4 channel bank is one of the most widely

used pieces of equipment in the North American

network today. The D3/D4 channel converts 24

analog telephone lines into the 24 channels of a T1

serial stream. The channel bank is the interface point

between a digital switching or transmission system

and the analog telephone loop. The industry is

moving

towards

end-to-end

digital

connections

(ISDN), but the analog channel bank will still be in

use for many years to come.

MH89770 Datasheet(PDF) 19 Page - Mitel Networks Corporation

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