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XRT79L71
PRELIMINARY
341
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
PAGE 342. for information on how the Jitter Attenuator block responds to a "FIFO Overflow" or "Underflow"
condition.
The next few sections describe how to configure and use the Jitter Attenuator block
5.2.5.2.2
Enabling the Jitter Attenuator Block and selecting the Jitter Attenuator FIFO Size
The user will both enable the Jitter Attenuator block and select (and implement) a FIFO size by writing the
appropriate values into Bits 0 (Jitter Attenuator PLL/FIFO Operation Mode - Bit 0) and 2 (Jitter Attenuator PLL/
FIFO Operation Mode - Bit 2), as depicted below.
Table 44 presents the relationship between the states of Bits 2 and 0 (within the "Jitter Attenuator Control"
Register) and the (1) Enable/Disable State of the Jitter Attenuator, and (2) the Size of the Jitter Attenuator
FIFO.
If the Jitter Attenuator is enabled, then it will perform its "Jitter Attenuation" processing on any DS3 or E3 signal
that passes through it. However, if the Jitter Attenuator is disabled, then the "Narrow-band" PLL (within the
Jitter Attenuator) will be by-passed. In this case, the Jitter Attenuator block will operate in a "transparent"
mode (e.g., the DS3 or E3 signal will pass through the Jitter Attenuator block with no jitter attenuation
processing performed on it, at all).
5.2.5.2.3
Configuring the Jitter Attenuator to operate in the Transmit or Receive Path
To configure the Jitter Attenuator block to operate in either the Transmit or Receive Direction, write the
appropriate value into Bit 1 (Jitter Attenuator in Transmit Path), within the "Jitter Attenuator Control" Register
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
Operating Mode
- Bit 1
Jitter Attenua-
tor in Transmit
Path
Jitter Attenua-
tor
PLL/FIFO
Operating
Mode
- Bit 0
R/O
R/W
0
X
0
X
TABLE 44: THE RELATIONSHIP BETWEEN THE STATES OF BITS 2 AND 0 (WITHIN THE "JITTER ATTENUATOR
CONTROL" REGISTER) AND THE (1) ENABLE/DISABLE STATE OF THE JITTER ATTENUATOR, AND (2) THE SIZE OF THE
JITTER ATTENUATOR FIFO
BIT 2
BIT 0
JITTER ATTENUATOR STATE
FIFO SIZE
00
ENABLED
16 BITS
0
1
Disabled
N/A
1
0
Enabled
32 bits
1
Disabled
N/A