ST70235A datasheet(12/28 Pages) STMICROELECTRONICS

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ST70235A

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Figure 6 : Generic TC Layer Functions

ATM Specific TC Layer Functions

The 2 bytes streams (fast and slow) are received

from the byte-based processing unit. When ATM

cells are transported, this block provides basic cell

functions

such

cell synchronization, cell

payload descrambling, idle/unassigned cell filter,

cell Header Error Correction (HEC) and detection.

The cell processing happens according to ITU-T

I.163 standard. Provision is also made for BER

measurements at this ATM cell level. When non

cell oriented byte streams are transported, the cell

processing unit is not active. The interface module

collects

cells

(from

the

cell-based

function

module). Cells are stored in FIFO’s (424 bytes or

8 cell wide, transmit buffers have the same size),

from which they are extracted by 2 interface

submodules, one providing a Utopia level 1

interface and the other a Utopia level 2 interface.

DATA PATX MERGER

INTERLEAVER

DE-INTERLEAVER

CODING

PMD

SCRAMBLER

PMD

SCRAMBLER

DECODING

FRAMER

DEFRAMER

ATM

Indication Bits AOC EOC

To/From

Demapper

FAST

DESCRAMBLER

Figure 7 : ATM Specific TC Layer Functions

Figure 8 : Interface Module

CELL SCRAMBLER

DESCRAMBLER

SYNCHRONIZER

CELL SCRAMBLER

DESCRAMBLER

SYNCHRONIZER

HEC

CELL

INSERTION/

FILTER

CELL

INSERTION/

FILTER

BER

FAST

SLOW

Interface

Module

From

Generic

LEVEL

UTOPIA

LEVEL

UTOPIA

LEVEL

UTOPIA

LEVEL

UTOPIA

FAST ATM

SLOW ATM

From

ATM

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