XRT72L13 Datasheet, PDF (344/370 Pages) Exar Corporation – M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC

XRT72L13
M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC
REV. P1.0.6
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PRELIMINARY
1. It should determine the current state of the “AIS”
condition. Recall, that this interrupt can gener-
ated, whenever the XRT72L13 Framer declares
or clears the AIS defects. Hence, the user can
determine the current state of the AIS defect by
reading the state of Bit 7 (RxAIS), within the
“RxDS3 Configuration & Status” Registers, as
illustrated below
RXDS3 CONFIGURATION & STATUS REGISTER (ADDRESS = 0X10)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
RxAIS
RxLOS
RxIdle
RxOOF
Reserved
Framing On
Parity
RO
RO
RO
RO
RO
RO
0
0
0
0
0
0
BIT 1
FSync
Algo
RO
0
BIT 0
MSync
Algo
RUR
0
If the AIS Condition is TRUE
1. The Local Terminal EquipmenIt should transmit a
FERF (Far-End Receive Failure) to the “Remote
Terminal Equipment”. The XRT72L13 Framer IC
automatically supports this action via the “FERF-
upon-AIS” feature.
2. It should transmit the appropriate FEAC Message
(per Bellcore GR-499-CORE), to the Remote Ter-
minal, indicating that a “Service Affecting” condi-
tion has been detected in the Local Terminal
Equipment.
If the AIS Condition is FALSE
1. The Local Terminal Equipment should cease
transmitting a FERF (Far-End Receive Failure)
indicator to the “Remote Terminal Equipment”.
The XRT72L13 Framer IC automatically supports
this action via the “FERF-upon-AIS” feature.
2. It should transmit the appropriate FEAC Message
(per Bellcore GR-499-CORE) to the Remote Ter-
minal, indicates that the “Service Affecting” condi-
tion no longer exists.
4.3.6.2.4 The “Change of State” of Receive Idle
Interrupt
If the “Change of State on Receive Idle” Interrupt is
enabled, then the XRT72L13 Framer IC will generate
an interrupt in response to either of the following con-
ditions.
1. When the XRT72L13 Framer IC detects an Idle
pattern, in the “incoming” DS3 data stream, and
2. When the XRT72L13 Framer IC no longer detects
the Idle pattern in the “incoming” DS3 data
stream.
Conditions causing the XRT72L13 Framer IC to
declare an Idle condition
• If the Receive DS3 Framer block (within the
XRT72L13 Framer IC) detects at least 63 DS3
frames, which contains the Idle pattern.
Conditions causing the XRT72L13 Framer IC to
clear the Idle condition.
• Whenever, the “Receive DS3 Framer” block
detects 63 DS3 frames, which do not contain the
Idle pattern.
Enabling and Disabling the “Change of State on
Receive Idle Interrupt:
The user can enable or disable the “Change of State
on Receive Idle” Interrupt, by writing the appropriate
value into Bit 4 (Idle Interrupt Enable) within the
“RxDS3 Interrupt Enable” Register, as illustrated be-
low.
RXDS3 INTERRUPT ENABLE REGISTER (ADDRESS = 0X12)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
CP Bit Error
Interrupt
Enable
LOS
Interrupt
Enable
AIS
Interrupt
Enable
Idle Interrupt
Enable
FERF
Interrupt
Enable
AIC
Interrupt
Enable
OOF
Interrupt
Enable
P-Bit Error
Interrupt
Enable
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Setting this bit-field to “1” enables this interrupt. Con- rupt.
versely, setting this bit-field to “0” disables this inter-
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