XRT72L13 Datasheet, PDF (341/370 Pages) Exar Corporation – M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC

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PRELIMINARY
XRT72L13
M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC
REV. P1.0.6
• It will set Bit 6 (LOS Interrupt Status) within the
“RxDS3 Interrupt Status” register to “1”, as illus-
trated below.
RXDS3 INTERRUPT STATUS REGISTER (ADDRESS = 0X13)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
CP-Bit Error
Interrupt
Status
LOS
Interrupt
Status
AIS
Interrupt
Status
Idle Interrupt
Status
FERF
Interrupt
Status
RUR
RUR
RUR
RUR
RUR
0
1
0
0
0
BIT 2
AIC
Interrupt
Status
RUR
0
BIT 1
OOF
Interrupt
Status
RUR
0
BIT 0
P-Bit Error
Interrupt
Status
RUR
0
Whenever the user’s system encounters the “Change
of LOS on Receive” Interrupt, then it should do the
following.
1. It should determine the current state of the “LOS”
condition. Recall, that this interrupt can gener-
ated, whenever the XRT72L13 Framer declares
or clears the LOS defects. Hence, the user can
determine the current state of the LOS defect by
reading the state of Bit 6 (RxLOS), 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
BIT 1
BIT 0
RxAIS
RxLOS
RxIdle
RxOOF
Reserved
Framing On
Parity
FSync
Algo
MSync
Algo
RO
RO
RO
RO
RO
RO
RO
RUR
0
1
0
0
0
0
0
0
If the LOS State is “TRUE”
1. It should transmit a FERF (Far-End Receive Fail-
ure) to the “Remote Terminal Equipment”. The
XRT72L13 Framer IC automatically supports this
action via the “FERF-upon-LOS” feature.
2. It should transmit the appropriate FEAC Message
(per Bellcore GR-499-CORE), to the Remote Ter-
minal, indicating that a “Loss of Signal” condition
has been declared.
If the LOS State is “FALSE”
1. It should cease transmitting a FERF indicator to
the “Remote Terminal Equipment”. The
XRT72L13 Framer IC automatically supports this
action via the “FERF-upon-LOS” feature.
2. It should transmit the appropriate FEAC Message
(per Bellcore GR-499-CORE), to the Remote Ter-
minal Equipment, indicating that the “Loss of Sig-
nal” condition has been cleared.
4.3.6.2.2 The “Change of State” on Receive
OOF Interrupt
If the “Change of State on Receive OOF (Out-of-
Frame)” Interrupt is enabled, then the XRT72L13
Framer IC will generate an interrupt in response to ei-
ther of the following conditions.
1. When the XRT72L13 Framer IC declares an OOF
(Out of Frame) condition, and
2. When the XRT72L13 Framer IC clears the OOF
(Out of Frame) condition.
Conditions causing the XRT72L13 Framer IC to
declare an OOF condition
• If the Receive DS3 Framer block (within the
XRT72L13 Framer IC) detects at least either 3 or 6
F-bit errors, in the last 16 F-bits.
Conditions causing the XRT72L13 Framer IC to
clear the OOF condition.
• Whenever, the “Receive DS3 Framer” block transi-
tions from the “M-Bit Search” into the “In-Frame”
state (within the “Frame Acquisition/Maintenance
State Machine Diagram).
Enabling and Disabling the “Change of State on
Receive OOF Interrupt:
The user can enable or disable the “Change of State
on Receive OOF” Interrupt, by writing the appropriate
value into Bit 1 (OOF Interrupt Enable) within the
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