PEF2091 Siemens Semiconductor Group, PEF2091 Datasheet - Page 64

• Manufacturer Part Number: PEF2091
• Description: ICs for Communications(ISDN Echocancellation Circuit)
• Manufacturer: Siemens Semiconductor Group

PEB 2091
PEF 2091
Functional Description
Control Block
Complete activation and deactivation procedures are implemented, which are controlled
®
by activation and deactivation indications from U, IOM
-2 or µP interfaces. State
transition of the procedures depend on the actual status of the Receiver (adaptation and
synchronization) and timing functions to watch fault conditions.
Embedded Operational Channel (EOC) Processor
Two different modes can be selected for maintenance functions: In the Auto mode all
EOC procedure handling and executing as specified by ANSI is performed. In the
Transparent mode all bits are transferred transparently to the user’s interfaces without
any internal processing.
See "Embedded Operations Channel (EOC)", page 69 for definition, and "Access to
EOC of U-Interface", page 110 for informations about programming and monitoring the
EOC.
Single Bits (SB) Processor
The single bits are used mainly to communicate status and maintenance functions
between the transceivers. The meaning of a bit position depends upon the direction of
transmission (upstream/downstream) and the operation mode (repeater or NT/LT). The
SB processor interprets these bits and gives access to some of them according to the
mode used. It also provides several filtering methods for SB indications.
See "Single Bits Channel", page 69 for definition, and "Access to the Single Bits of
U-Interface", page 115 for informations about programming and monitoring the SB.
Special Functions (SF)
This block provides miscellaneous functions of the SIU, like the power controller function
in stand-alone mode, access to internal chip data, test loops control, S/G bit control in
µP mode and others. These will be discussed in detail in chapter 4.
Cyclic Redundancy Check (CRC)
The cyclic redundancy check provides a possibility to verify the correct transmission of
data. The check sum of a transmitted U-superframe is calculated from the bits in the
D-channel, both B-channels, and the M4 bits according to the CRC polynomial
12
11
3
2
G (u) = u
+ u
+ u
+ u
+ u + 1
(+ modulo 2 addition)
Semiconductor Group
64
Data Sheet 01.99