XRT86VL3X datasheet(40/154 Pages) EXAR

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XRT86VL3X

T1/E1/J1 FRAMER/LIU COMBO - ARCHITECTURE DESCRIPTION

REV. 1.2.3

4.0

OVERHEAD INTERFACE BLOCK

The XRT86VL3x has the ability to extract or insert DS1 data link information from or into the following:

• Facility Data Link (FDL) bits in ESF framing format mode

• Signaling Framing (Fs) bits in SLC®96 and N framing format mode

• Remote Signaling (R) bits in T1DM framing format mode

The source and destination of these inserted and extracted data link bits would be from either the internal

HDLC Controller or the external device accessible through DS1 Overhead Interface Block. The operation of

the Transmit Overhead Input Interface Block and the Receive Overhead Output Interface Block will be

discussed separately.

4.1

DS1 Transmit Overhead Input Interface Block

4.1.1

Description of the DS1 Transmit Overhead Input Interface Block

The DS1 Transmit Overhead Input Interface Block will allow an external device to be the provider of the Facility

Data Link (FDL) bits in ESF framing format mode, Signaling Framing (Fs) bits in the SLC96 and N framing

format mode and Remote Signaling (R) bit in T1DM framing format mode. This interface provides interface

signals and required interface timing to shift in proper data link information at proper time.

The Transmit Overhead Input Interface for a given Framer consists of two signals.

• TxOHClk_n: The Transmit Overhead Input Interface Clock Output signal

• TxOH_n: The Transmit Overhead Input Interface Input signal.

The Transmit Overhead Input Interface Clock Output pin (TxOHCLK_n) generates a rising clock edge for each

data link bit position according to configuration of the framer. The Data Link equipment interfaced to the

Transmit Overhead Input Interface block should update the data link bits on the TxOH_n line upon detection of

the rising edge of TxOHClk_n. The Transmit Overhead Input Interface block will sample and latch the data link

bits on the TxOH_n line on the falling edge of TxOHClk_n. The data link bits will be included and transmitted

via the outgoing DS1 frames.

The figure below shows block diagram of the DS1 Transmit Overhead Input Interface of XRT86VL3x.

4.1.2

Configure the DS1 Transmit Overhead Input Interface module as source of the Facility Data

Link (FDL) bits in ESF framing format mode

The FDL bits in ESF framing format mode can be inserted from:

• DS1 Transmit Overhead Input Interface Block

• DS1 Transmit HDLC Controller

• DS1 Transmit Serial Input Interface.

FIGURE 34. BLOCK DIAGRAM OF THE DS1 TRANSMIT OVERHEAD INPUT INTERFACE OF THE XRT86VL3X

Transmit

Overhead Input

Interface

TxOH_n

TxOHClk_n

To Transmit

Framer Block

XRT86VL3X Datasheet(PDF) 40 Page - Exar Corporation

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