XRT79L71 datasheet(70/434 Pages) EXAR

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XRT79L71

1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC - REGISTER/MAP DESCRIPTION

REV. 1.0.0

1 - 0

Transmit Mode[1:0]

R/W

Transmit POS-PHY Interface Mode[1:0]:

These two READ/WRITE bit-fields, along with Bit 0 (Transmit

POS-PHY Level 2 Packet Mode) within the Transmit POS-PHY

Interface - Transmit Control Register Byte 2 permit the user to

configure the Transmit POS-PHY Interface block to operate in

any of the following modes.

• The Level 2, Packet Mode

• The Level 2, Chunk Mode

• The Level 3, Packet Mode

• The Level 3, Out-of-Band, Chunk Mode

• The Level 3, In-Band, Chunk Mode

The following table presents the relationship between these

three bits that the corresponding mode of the Transmit POS-

PHY Interface block.

A brief description of the Transmit POS-PHY Level 2 and 3

Modes are presented below.

If the Transmit POS-PHY Interface block is configured to

operate in the POS-PHY Level 2 Mode

If the Transmit POS-PHY Interface block is configured to operate

in the POS-PHY Level 2 Mode, then all of the following is true.

• When polling, the Receive POS-PHY Interface block will drive

the TxPPA output pin to the appropriate level (reflecting the

TxFIFO fill-status) within ONE TxPClk period (in lieu of two

TxPClk periods) after sampling a given POS-PHY Port

Address via the TxPAddr[4:0] input pins.

If the Transmit POS-PHY Interface block is configured to

operate in the POS-PHY Level 3 Mode

If the Transmit POS-PHY Interface block is configured to operate

in the POS-PHY Level 3 Mode, then all of the following are true.

• When polling, the Transmit POS-PHY Interface block will drive

the TxPPA output pin to the appropriate level (reflecting the

TxFIFO fill-status) within TWO TxPClk periods (in lieu of one

TxPClk periods) after sampling a given POS-PHY Port

Address via the TxPAddr[4:0] input pins.

BIT NUMBER

NAME

TYPE

DESCRIPTION

Resulting Mode of Operation

Level 2, Chunk Mode

Level 3, Out-of-Band Chunk Mode

Level 3, In-Band Chunk Mode

Level 3, Packet Mode

Level 2, Packet Mode

Transmit

Level 2 Mode

Transmit

Mode[1:0]

XRT79L71 Datasheet(PDF) 70 Page - Exar Corporation

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