PEB2256HT datasheet(94/490 Pages) INFINEON

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FALC56 V1.2

PEB 2256

Functional Description E1

Data Sheet

2002-08-27

4.4

Transmit Path in E1 Mode

4.4.1

Transmitter (E1)

The serial bit stream is processed by the transmitter which has the following functions:

• Frame/multiframe synthesis of one of the two selectable framing formats

• Insertion of service and data link information

• AIS generation (Alarm indication signal)

• Remote alarm generation

• CRC generation and insertion of CRC bits

• CRC bits inversion in case of a previously received CRC error

• Idle code generation per DS0

The frame/multiframe boundaries of the transmitter can be externally synchronized by

using the SYPX/XMFS pin. Any change of the transmit time slot assignment

subsequently produces a change in the framing bit positions on the line side. This feature

is required if signaling and service bits are routed through the switching network and are

inserted in transmit direction by the system interface.

In loop-timed configuration (LIM2.ELT = 1) disconnecting the control of the transmit

system highway from the transmitter is done by setting XSW.XTM. The transmitter is

now in a free running mode without any possibility to update the multiframe position in

case of changing the transmit time slot assignment. The framing bits are generated

independently of the transmit system interface. For proper operation the transmit elastic

buffer size should be programmed to 2 frames.

The contents of selectable time slots can be overwritten by the pattern defined by

registers ICB1…ICB4.

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