PEB22554 SIEMENS [Siemens Semiconductor Group], PEB22554 Datasheet - Page 60

• Manufacturer Part Number: PEB22554
• Description: ICs for Communications
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

PEB 22554
Functional Description E1
Transmitter
The serial bit stream is then 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 boundries of the transmitter may be externally synchronized by
using the SYPX / XMFS pin. Any change of the transmit time-slot assignment will
subsequently produce a change of 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 via the system interface.
In loop-timed configuration (LIM2.ELT) 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 actualize the multiframe position in case of
changing the transmit time-slot assignment. The framing bits are generated independent
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 via
register IDLE. The selection of “idle channels” is done by programming the four-byte
registers ICB1 … ICB4.
Semiconductor Group
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