XRT72L52
129
REV. 1.0.3
TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
Writing a “1” to this bit-field causes the Framer IC to toggle the Encodis output pin "High”. Writing a “0” to this
bit-field will cause the Framer IC to toggle this output pin "Low”.
NOTES:
1.
The B3ZS/HDB3 encoder, within the XRT73L02A is not to be confused with the B3ZS/HDB3 encoding capabilities
that exists within the Transmit DS3/E3 Framer block of the Framer IC.
2.
The user is advised to disable the B3ZS/HDB3 encoder (within the XRT73L02A IC) if the Transmit and Receive
DS3/E3 Framer (within the XRT72L52) are configured to operate in the B3ZS/HDB3 line code.
3.
If the customer is not using the XRT73L02A DS3/E3/STS-1 LIU IC, then this bit-field and the Encodis output pin
can be used for other purposes.
Bit 2 - TxLEV (Transmit Line Build-Out Enable/Disable Select)
This Read/Write bit-field allows the user to control the state of the TxLEV output pin of the Framer device. This
output pin is intended to be connected to the TxLEV input pin of the XRT73L02A DS3/E3/STS-1 LIU IC.
Writing a “1” to this bit-field commands the Framer to drive the TxLEV output pin "High”.
Writing a “0” to this bit-field commands the Framer to drive this output signal "Low”.
If the user commands this signal to toggle "High”, then the Transmit Line Build-Out circuitry, within the
XRT73L02A will be disabled. In this mode, the XRT73L02A LIU IC will generate unshaped (e.g., square)
pulses out onto the line, via the TTIP and TRING output pins.
Conversely, if the user commands this signal to toggle "Low”, then the Transmit Line Build-Out circuitry, within
the XRT73L02A will be enabled. In this mode, the XRT73L02A will generate shaped pulses onto the line, via
the TTIP and TRING output pins.
In order to comply with the Isolated DSX-3 Pulse Template requirements (per Bellcore GR-499-CORE), the
user is advised to set this bit-field to “0” if the cable length (between the transmit output of the XRT73L02A and
the DSX-3 Cross Connect System) is less than 225 feet. Conversely, the user is advised to set this bit-field to
“1” if the cable length (between the transmit output of the XRT73L02A and the DSX-3 Cross Connect System)
is greater than 225 feet.
NOTE: If the customer is not using the XRT73L02A DS3/E3/STS-1 IC, then this bit-field and the TxLEV output pin can be
used for other purposes.
Bit 1 - RLOOP (Remote Loop-Back Select)
This Read/Write bit-field permits the user to control the state of the RLOOP output pin of the Framer device.
This output pin is intended to be connected to the RLOOP input pin of the XRT73L02A LIU IC.
The state of this bit-field (or pin) along with LLOOP 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 mode (within
the XRT73L02A) is tabulated below.
Writing a “1” into this bit-field commands the Framer to drive the RLOOP output signal "High”. Writing a “0” into
this bit-field commands the Framer to drive this output signal "Low”.
TABLE 18: THE RELATIONSHIP BETWEEN THE STATES OF RLOOP, LLOOP AND THE RESULTING LOOP-BACK MODE
WITH THE
XRT73L02A
RLOOP
LLOOP
RESULTING LOOP-BACK MODE (WITHIN THE XRT73L02A DS3/E3/STS-1 LIU IC)
0
Normal Mode (No Loop-back)
0
1
Analog Local Loop-back Mode
1
0
Remote Loop-back Mode
1
Digital Local Loop-back Mode