28233-11 View Datasheet(PDF) - Conexant Systems

Part Name

Description

Manufacturer

28233-11

ATM Transmitter/Receiver with UTOPIA Interface

Conexant Systems 

CN8223

ATM Transmitter/Receiver with UTOPIA Interface

1.0 Product Description

1.4 ATM Cell Processing Functions

1.4.1 Cell Generation Functions

The CN8223 ATM cell processing block provides flexible control for cell

generation. Cell generation is the formatting of 48-octet payload segments into

53-octet ATM cells, and the generation of appropriate header octets, HEC, and

payload Cyclic Redundancy Check (CRC) calculations as required by the AAL

formats. The CN8223 provides modes that perform this cell generation function,

along with modes that allow insertion of any or all of the various header fields

from either the FIFO interface or from microprocessor control registers. Four cell

generation modes are available in the CN8223. Cell generation functions are

described in detail in Section 2.6.

1.4.2 Tx Rate Control

Two Rate Control registers [0x08, 0x09] are provided for each of the four ports to

allow programmable rate shaping of cell transmission. The ratio of active to idle

cells is programmable with 0.4 % granularity. Status counts of non-idle cells

transmitted are maintained for each of the four sources.

1.4.3 Cell Validation Functions

Cell validation refers to the checking of cells coming in from the PHY block for

proper format. The CN8223 provides modes that deliver 48-, 52-, or 53-octet

cells, or 57-octet PLCP slots to the FIFO output ports. The validation process is

described in detail in Section 2.6.

Protocol verification includes HEC validation with ATM or SMDS/802.6

coverage, validation of payload length per segment type, and correct payload

CRC value. Status reporting of validation steps is via error counters and status

register indications. Status bits can be programmed to generate interrupts to the

microprocessor. Each validation step can be individually disabled.

100046C

Conexant

1-9

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