Samsung LNB50 Bedienungsanleitung PDF herunterladen (Seite 97)

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ISDN U Interface

The Lucent T7256A NT1 device provides the two-wire 2B+D U interface to

provide two-wire network termination. The NT1 device processes the ISDN BRI

bit stream that consists of two 64-Kbit/s B channels and a single 16-Kbit/s

D channel. The U interface circuit includes a line fuse, U transformer, DC

termination IC, and opto-isolation circuitry.

The U interface default configuration uses the Am186CC or Am186CH

microcontroller SSI interface to configure the NT1; the NT1 TDM bus is used to

transfer data between the NT1 device and either the microcontroller’s integrated

HDLC in PCM mode, or the POTS interface.

The microcontroller’s SSI interface to the NT1 microprocessor’s serial interface is

controlled by the PLD (U13). The PLD is required to select the NT1

microprocessor’s serial interface because the NT1 device does not have an SSI chip

enable, and the development module’s POTS interface DSLAC device also has an

SSI interface. The PLD uses the Am186CC or Am186CH microcontroller’s PIO38

signal asserted Low to pass the SSI clock to the NT1 device during NT1

configuration.

The NT1 TDM bus is the PCM clock master and the upstream device to the

Am186CC or Am186CH microcontroller and the DSLAC device in the POTS

interface. In this configuration, the TDM bus drives the PCM data clock and frame

sync, and transmits data directly to and from the Am186CC or Am186CH

microcontroller and the DSLAC device in the POTS interface.

An alternate configuration option uses the Am79C32A DSC circuit and T7256A

device together on the module. In this configuration, data is transferred between

the Am186CC or Am186CH microcontroller’s integrated HDLC and the

Am79C32A DSC circuit. The T7256A NT1 device communicates with the

Am79C32A DSC circuit through its S/T interface. See Table 3-3 on page 3-16 for

configuration information.

CR7 is used for NT1 device status. The four states of the LED are off, on, 1 Hz,

and 8 Hz. Table 3-4 on page 3-16 shows the U interface LED status. The schematic

for the U interface block is shown in Figure 3-10 on page 3-17 (or sheet 7 of the

development module schematics included in your kit).

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Samsung LNB50 Bedienungsanleitung Seite 97