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PRELIMINARY
XRT79L71
342
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
Setting this bit-field to "0" configures the Jitter Attenuator to operate in the "Receive Path". Conversely, setting
this bit-field to "1" configures the Jitter Attenuator to operate in the "Transmit Path".
5.2.5.2.4
Alarm Conditions occurring within the Jitter Attenuator Block
conditions occur if the distance between the "FIFO_READ" and "FIFO_WRITE" pointers reach 0 bits. In either
of these conditions an error-condition is said to have occurred. The XRT79L71 contains some circuitry to alert
the system that the distance between the FIFO_WRITE and FIFO_READ pointers has fallen to at least two (2)
bit-positions. If this condition were to occur, then Jitter Attenuator FIFO is on the verge of experiencing either a
"FIFO Under-run" or "Overflow" condition. In response to this condition, the XRT79L71 will notify the Line Card
circuitry of this phenomenon by declaring a "FIFO Limit" Alarm condition. The XRT79L71 will indicate that it is
declaring a "FIFO Limit Alarm" condition by doing all of the following.
1.
It will set Bit 3 (FIFO Limit Alarm Declared), within the LIU Alarm Status Register, to "1" as depicted
below.
2.
It will also generate the "Change of FL Condition" Interrupt.
The XRT79L71 will indicate that it is
generating this interrupt by
a.
Asserting the Interrupt Request output pin (e.g., by toggling it "LOW")
b. Setting Bit 3 (Change of FL Condition Interrupt Status) within the "LIU Interrupt Status" Register to
"1" as depicted below.
Jitter Attenuator Control Register (Address = 0x1307)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Unused
DFL
Jitter Attenuator
FIFO Pointer
RESET
Jitter Attenuator
PLL/FIFO Oper-
ating Mode - Bit 1
Jitter Attenuator
in Transmit Path
Jitter Attenuator
PLL/FIFO Oper-
ating Mode - Bit 0
R/O
R/W
0
X
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
Condition
R/O
0
1
0