á
á THREE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER XRT72L53
PRELIMINARY
REV. P1.1.7
144
NOTE: If the customer is not using the XRT7300 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 is used to control the state of
the RLOOP output pin of the Framer. This output pin
is intended to be connected to the RLOOP input pin
of the XRT73001 LIU IC.
The state of this bit-field (or pin) along with LLOOP
are used to configure the XRT7300 into one of four
(4) loop-back modes. The relationship of the values of
RLOOP, LLOOP and the resulting loop-back mode
(within the XRT7300) 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”.
For a detailed description of the XRT7300 LIU’s oper-
ation during each of these loop-back modes, please
see the XRT7300 DS3/E3/STS-1 LIU IC data sheet.
NOTE: If the customer is not using the XRT7300 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 is used to control the state of
the LLOOP output pin of the Framer. This output pin
is intended to be connected to the LLOOP input pin of
the XRT7300 DS3/E3/STS-1 LIU IC.
The state of this bit-field (or pin) along with RLOOP
are used to configure the XRT7300 into one of four
(4) loop-back modes. The relationship of the values of
RLOOP, LLOOP and the resulting loop-back modes
(within the XRT7300) are presented in
Table 16.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 XRT7300 LIU’s oper-
ation during each of these loop-back modes, please
see the XRT7300 DS3/E3/STS-1 LIU IC Data Sheet.
NOTE: If the customer is not using the XRT7300 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 XRT7300 contains three output pins which can
be made accessible to the Microprocessor Interface,
via the Line Interface Scan register. These three out-
put 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 de-
picted below.
The meaning/role of each of these bit-field and their
corresponding input pins are defined below.
Bit 2 - DMO - Drive Monitor Output
TABLE 16: THE RELATIONSHIP BETWEEN THE STATES OF RLOOP, LLOOP AND THE RESULTING LOOP-BACK MODE
WITH THE
XRT7300
RLOOP
LLOOP
RESULTING LOOP-BACK MODE (WITHIN THE XRT7300 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
LINE INTERFACE SCAN REGISTER (ADDRESS = 0X81)
BIT 7BIT 6BIT 5BIT 4BIT 3BIT 2BIT 1BIT 0
Not Used
DMO
RLOL
RLOS
R/O
0
0000
000