XRT84L38IB Exar Corporation, XRT84L38IB Datasheet - Page 346

• Manufacturer Part Number: XRT84L38IB
• Description: Network Controller & Processor ICs 8 Ch T1/E1 Framer
• Manufacturer: Exar Corporation

Specifications of XRT84L38IB

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

XRT84L38
OCTAL T1/E1/J1 FRAMER
The Robbed-bit Signaling Enable bit of the Transmit Signaling Control Register (TSCR) determines whether
Robbed-bit Signaling is available. The table below shows configurations of the Robbed-bit Signaling Enable bit
of the Transmit Signaling Control Register (TSCR).
TRANSMIT SIGNALING CONTROL REGISTER (TSCR) (INDIRECT ADDRESS = 0XN2H, 0X40H - 0X57H)
The XRT84L38 T1/J1/E1 Octal Framer can be configured to monitor quality of received DS1 frames. It can
generate error indications if the local receive framer has received error frames from the remote terminal. If
corresponding interrupt is enabled, the local microprocessor operation is interrupted by these error conditions.
Upon microprocessor interruption, the user can intervene by looking into the error conditions.
At the same time, the user can configure the XRT84L38 framer to transmit alarms and error indications to
remote terminal. Different alarms and error indications will be transmitted depending on the error condition.
The section below gives a brief discussion of the error conditions and appropriate alarms that should be
generated and transmitted by the XRT84L38 framer.
As defined in ANSI T1.231 specification, alarm conditions are created from defects. Defects are momentary
impairments present on the DS1 trunk. If a defect is present for a sufficient amount of time (called the
integration time), then the defect becomes an alarm. Once an alarm is declared, the alarm is present until after
the defect clears for a sufficient period of time. The time it takes to clear an alarm is called the de-integration
time.
Alarms are used to detect and warn maintenance personnel of problems on the DS1 trunk. There are three
types of alarms:
•
•
•
To explain the error conditions and generation of different alarms, let us create a simple DS1 system model. In
this model, a DS1 signal is sourced from the Central Office (CO) through a Repeater to the Customer Premises
9.6
9.6.1
N
Red alarm or Service Alarm Indication (SAI) Signal
Blue alarm or Alarm Indication Signal (AIS)
Yellow alarm or Remote Alarm Indication (RAI) Signal
UMBER
B
1-0
IT
How to Configure the XRT84L38 Framer to Generate and Transmit Alarms and Error Indications
to Remote Terminal
Brief discussion of alarms and error conditions
Signaling Enable
Robbed-bit
B
IT
N
AME
B
IT
R/W
T
YPE
0 - Robbed-bit Signaling is disabled. No signaling data will be inserted into
the input PCM data no matter what the setting of the Transmit Signaling
Source Select [1:0] bits is.
1 - Signaling data is enabled and inserted into the input DS1 PCM data
according to setting of the Transmit Signaling Source Select [1:0] bits.
326
B
IT
D
ESCRIPTION
REV. 1.0.1