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XRT79L71
PRELIMINARY
185
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
It will generate the Change of LOL (Loss of Lock) Defect Condition Interrupt. The XRT79L71 will indicate
that it is generating this interrupt by (a) asserting the Interrupt Request output pin (by toggling it "Low"), and
(b) by setting Bit 2 (Change of LOL Condition Interrupt), within the LIU Interrupt Status Register, to "1" as
depicted below.
For the duration that the Clock and Data Recovery block is declaring the LOL Defect Condition then all of the
following will be true.
The Clock and Data Recovery block will be synthesizing a 44.736MHz clock signal that is derived from the
Reference clock signal (which originates from the SFM Synthesizer block).
The Clock and Data Recovery block will route this 44.736MHz clock signal to all down-stream circuitry (e.g.,
the Receive DS3/E3 Framer block, etc.). Each of these down-stream blocks will use this 44.736MHz clock
signal as their timing source.
The Clock and Data Recovery Block and its LOL Defect Declaration Behavior during Signal Present
and No Signal Present Conditions
Once the Clock and Data Recovery Block has declared the LOL Defect Condition, then any subsequent
behaviour of the Clock and Data Recovery Block, depends upon whether the AGC Block (within the Receive
DS3/E3 LIU Block) determines that some sort of signal energy is present (at the RTIP/RRING input pins) or
not.
If No Signal is present at the RTIP/RRING Input Pins
If the incoming DS3 line signal were to be removed, such that there is absolutely no signal energy being
applied to the RTIP/RRING input pins, then all of the following will happen.
The Receive DS3/E3 LIU Block will declare the LOS Defect Condition (please see Section 4.3.1.6 for more information on how the Receive DS3/E3 LIU Block declares the LOS Defect Condition).
LIU Alarm Status Register (Address = 0x1303)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Unused
Digital LOS
Defect
Declared
Analog LOS
Defect
Declared
FL (FIFO
Limit) Alarm
Declared
Receive LOL
Defect
Declared
Receive LOS
Defect
Declared -
Receive
DS3/E3 LIU
Block
Transmit
DMO Condi-
tion
R/O
0
1
0
LIU Interrupt Status Register (Address = 0x1302)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Unused
Change of
FL
Condition
Interrupt
Status
Change of
LOL
Condition
Interrupt
Status
Change of
LOS
Condition
Interrupt
Status
Change of
DMO
Condition
Interrupt
Status
R/O
RUR
0
1
0