
XRT72L52
130
TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. 1.0.3
For a detailed description of the XRT73L02A LIU’s operation during each of these loop-back modes, refer to
the XRT73L02A DS3/E3/STS-1 LIU IC data sheet.
NOTE: If the customer is not using the XRT73L02A DS3/E3/STS-1 LIU IC, then this bit-field and the RLOOP output pin can
be used for other purposes.
Bit 0 - LLOOP (Local Loop-back Select)
This Read/Write bit-field allows the user to control the state of the LLOOP output pin of the Framer device.
This output pin is intended to be connected to the LLOOP input pin of the XRT73L02A DS3/E3/STS-1 LIU IC.
The state of this bit-field (or pin) along with RLOOP are used to configure the XRT73L02A into one of four (4)
loop-back modes. The relationship of the values of RLOOP, LLOOP and the resulting loop-back modes (within
the XRT73L02A) are presented in Table 18.
Writing a “1” into this bit-field commands the Framer to toggle the LLOOP output pin "High”. Writing a “0” into
this bit-field commands the Framer to toggle this output signal "Low”.
For a detailed description of the XRT73L02A LIU’s operation during each of these loop-back modes, refer to
the XRT73L02A DS3/E3/STS-1 LIU IC Data Sheet.
NOTE: If the customer is not using the XRT73L02A DS3/E3/STS-1 LIU IC, then this bit-field and the LLOOP output pin can
be used for other purposes.
3.2
Bit-Fields within the Line Interface Scan Register
The XRT73L02A contains three output pins which can be made accessible to the Microprocessor Interface, via
the Line Interface Scan register. These three output pins are listed below.
DMO - Drive Monitor Output
RLOL - Receive Loss of Lock Indicator
RLOS - Receive Loss of Signal Indicator.
The logic state of each of these input pins (or output pins from the LIU) can be monitored by reading the
contents of the Line Interface Scan register, as depicted below.
Bit 2 - DMO - Drive Monitor Output
This Read-Only bit-field indicates the logic state of the DMO output pin of the Framer device. This input pin is
intended to be connected to the DMO output pin of the XRT73L02A DS3/E3/STS-1 LIU IC. If this bit-field
contains a logic “1”, then the DMO input pin is "High”. The XRT73L02A DS3/E3/STS-1 LIU IC will set this pin
"High” if the Transmit Driver Monitor circuitry (within the XRT73L02A) has not detected any bipolar signals at
the MTIP and MRING inputs (of the XRT73L02A) within the last 128 + 32 bit periods.
Conversely, if this bit-field is set to “0”, then the DMO input pin is "Low”. The XRT73L02A DS3/E3/STS-1 LIU
IC will set this pin "Low” if bipolar signals are being detected at the MTIP and MRING input pins.
For more information on the user/purpose of the Drive Monitor feature, within the XRT73L02A LIU IC, refer to
the XRT73L02A DS3/E3/STS-1 LIU IC Data Sheet.
NOTE: If this customer is not using the XRT73L02A DS3/E3/STS-1 LIU IC, then this register bit-field and input pin can be
used for a variety of other purposes.
Bit 1 - RLOL - Receive Loss of Lock
LINE INTERFACE SCAN REGISTER (ADDRESS = 0X81)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Not Used
DMO
RLOL
RLOS
RO
0
1