
XRT7250
DS3/E3 FRAMER IC
á
REV. 1.1.1
112
For a detailed description of the XRT7300 DS3/E3
LIU's operation, during each of these above-men-
tioned loop-back modes, please consult 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.
2.3.8.20 Line Interface Scan Register
Bit 2 - DMO - (Drive Monitor Output)
This Read-Only bit-field indicates the logic state of
the DMO input pin of the Framer device. This input
pin is intended to be connected to the DMO output
pin of the XRT7300 DS3/E3 LIU IC. If this bit-field
contains a logic "1", then the DMO input pin is "High".
The XRT7300 DS3/E3 LIU IC will set this pin "High" if
the drive monitor circuitry (within the XRT7300 de-
vice) has not detected any bipolar signals at the MTIP
and MRING inputs (of the XRT7300 device) within the
last 128 + 32 bit periods.
Conversely, if this bit-field contains a logic "0", then
the DMO input pin is "High". The XRT7300 DS3/E3
LIU IC will set this pin "Low" if bipolar signals are be-
ing detected at the MTIP and MRING input pins.
NOTE: If this customer is not using the XRT7300 DS3/E3
LIU IC, then this 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 XRT7300 DS3/E3 LIU IC. If this bit-field
contains a logic "1", then the RLOL input pin is
"High". The XRT7300 DS3/E3 LIU IC will set this pin
"High" if the clock recovery phase-locked-loop circuit-
ry (within the XRT7300 device) has lost lock with the
incoming DS3/E3 data-stream and is not properly re-
covering clock and data.
Conversely, if this bit-field contains a logic "0", then
the RLOL input pin is "Low". The XRT7300 DS3/E3
LIU IC will hold this pin "Low" as long as this clock re-
covery phase-locked-loop circuitry (within the
XRT7300 device) is properly locked onto the incom-
ing DS3 data-stream, and is properly recovering clock
and data from this data-stream.
For more information on the operation of the
XRT7300 DS3/E3/STS-1 LIU IC, please consult the
XRT7300 DS3/E3/STS-1 LIU IC data sheet.
NOTE: If the customer is not using the XRT7300 DS3/E3/
STS-1 IC, then this bit-field, and the RLOL input pin can be
used for other purposes.
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 XRT7300 DS3/E3 LIU IC. If this bit-field
contains a logic "1", then the RLOS input pin is
"High". The XRT7300 device will toggle this signal
"High" if it (the XRT7300 LIU IC) 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 XRT7300 device
will hold this signal "Low" if it is NOT currently declar-
ing an LOS (Loss of Signal) condition.
For more information on the LOS Declaration and
Clearance criteria of the XRT7300 device, please
consult the XRT7300 DS3/E3/STS-1 LIU IC data
sheet.
NOTE: Asserting the RLOS input pin will cause the
XRT7250 Framer IC device to generate the Change in LOS
Condition interrupt and declare an LOS (Loss of Signal)
condition. Therefore, this input pin should not be used as a
general purpose input.
2.4
THE LOSS OF CLOCK ENABLE FEATURE
The timing for the Microprocessor Interface section,
originates from a line rate (e.g., either a 34.368MHz
or 44.736 MHz) signal that is provided by either the
TxInClk or the RxLineClk signals. However, if the
Framer device experiences a Loss of Clock signal
event such that neither the TxInClk nor the RxLineClk
signal are present, then the Framer Microprocessor
Interface section cease to function.
The Framer device offers a Loss of Clock (LOC) pro-
tection feature that allows the Microprocessor Inter-
face section to at least complete or terminate an in-
process Read or Write cycle (with the local P)
should this Loss of Clock event occur. The LOC cir-
cuitry consists of a ring oscillator that continuously
LINE INTERFACE SCAN REGISTER (ADDRESS = 0X81)
BIT 7BIT 6BIT 5BIT 4BIT 3BIT 2BIT 1BIT 0
DMO
RLOL
RLOS
RO
00
000