XRT72L52
REV. 1.0.1
xr
TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
126
3.2
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 con-
tents of the Line Interface Scan register, as depicted below.
B
IT
-F
IELDS
WITHIN
THE
L
INE
I
NTERFACE
S
CAN
R
EGISTER
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 con-
tains 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.
N
OTE
:
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
This Read-Only bit-field indicates the logic state of the RLOL input pin of the Framer device. This input pin is
intended to be connected to the RLOL output pin of the XRT73L02A DS3/E3/STS-1 LIU IC. If this bit-field con-
tains a logic “1”, then the RLOL input pin is "High”. The XRT73L02A LIU IC will drive this pin "High” if the clock
recovery phase locked loop circuitry (within the XRT73L02A) has lost lock with the incoming DS3 or E3 data-
stream and is not properly recovering clock and data.
Conversely, if this bit-field contains a logic “0”, then the RLOL input pin is "Low”. The XRT73L02A DS3/E3/
STS-1 LIU IC will hold this pin "Low” for as long as this clock recovery phase-locked-loop circuit (within the
XRT73L02A) is properly locked onto the incoming DS3 or E3 data stream and is properly recovering clock and
data from this data stream.
Bit 0 - RLOS- Receive Loss of Signal
This Read-Only bit-field indicates the logic state of the RLOS input pin of the Framer device. This input pin is
intended to be connected to the RLOS output pin of the XRT73L02A DS3/E3/STS-1 LIU IC. If this bit-field con-
tains a logic “1”, then the RLOS input pin is "High”. The XRT73L02A LIU IC will drive this signal "High” if it is
currently declaring an LOS (Loss of Signal) condition.
Conversely, if this bit-field contains a logic “0”, then the RLOS input pin is "Low”. The XRT73L02A LIU IC will
drive this signal "Low”, if it is NOT currently declaring an LOS (Loss of Signal) condition.
For more information on the LOS Declaration/Clearance criteria, used by the XRT73L02A, refer to the
XRT73L02A DS3/E3/STS-1 LIU IC Data Sheet.
LINE INTERFACE SCAN REGISTER (ADDRESS = 0X81)
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
Not Used
DMO
RLOL
RLOS
RO
RO
RO
RO
RO
RO
RO
RO
0
0
0
0
0
0
1
1