XRT86L30
REV. 1.0.1
SINGLE T1/E1/J1 FRAMER/LIU COMBO
7.0 OVERHEAD INTERFACE BLOCK
The XRT86L30 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.
7.1
DS1 Transmit Overhead Input Interface Block
7.1.1
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 XRT86L30.
FIGURE 36. BLOCK
D
IAGRAM OF THE DS1 TRANSMIT
O
VERHEAD
INPUT
INTERFACE OF THE XRT86L30
TxOH_n
TxOHClk_n
Transmit
Overhead Input
Interface
To Transmit
Framer Block
7.1.2
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.
170
EXAR [ EXAR CORPORATION ]
