ST5451 datasheet(19/34 Pages) STMICROELECTRONICS

19 / 34 page

TYPICAL APPLICATIONS

ST5451 HDLC controller may be used in TE,

NT2, NT12 or LT.

Figures 6 to 8 illustrate three typical applications

in multifunctional TE.

The D channel containing only signalling is proc-

essed by the LAPD controller and routed via a

parallel

µP interface to the terminal processor.

The support of the LAPD protocol which is imple-

mented by the HDLC controller device allows in

cost senstive applications the use of a low cost

microprocessor. See fig. 6.

Fig. 7 illustrates a configuration in which the D

channel containing signalling data (SAPI s) as

well as packet switched data (SAPI p) is proc-

essed by two controllers and two independent mi-

croprocessors.

Fig. 8 illustrates a configuration in which one mi-

croprocessor is connected to two controllers via a

DMA controller.

D channel with LAPD signalling data and B chan-

nel LAPB packet data are processed by the same

µP. A DMA controller performs device to memory

transfers. It is a typical work station application.

Fig. 9 and 10 illustrate 2 typical applications in

NT2 or exchange.

An NT2 or LT in fig.9 with eight D channel control-

lers connected to the GCI interface handle sub-

scriber 0 to 7. Any GCI compatible transceiver (S

or U) may be used to do the subscriber line inter-

face; a GCI compatible exchange circuit may im-

plement the system interface. This is one decen-

tralized application.

Fig. 10 illustrates a centralized application. Using

a switching net work, it is possible to connect:

up to thirty two 64 Kbit/s channels on a 2 Mb/s

PCM highway to 32 B channel controllers

up to sixty four 64 Kbit/s channels on a 4 Mb/s

PCM highway to 64 B channel controllers

up to two hundred fifty six D channels on a 4 Mb/s

highway to 256 D channel controllers.

Figure 6: Low cost GCI terminal application

ST5451

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