XRT72L56 Datasheet, PDF (261/486 Pages) Exar Corporation – SIX CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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SIX CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
PRELIMINARY
value into Bit 1 (OOF Interrupt Enable) within the
RxDS3 Interrupt Enable Register, as illustrated below.
RXDS3 INTERRUPT ENABLE REGISTER (ADDRESS = 0X12)
XRT72L56
REV. P1.1.2
BIT 7
CP Bit Error
Interrupt
Enable
R/W
0
BIT 6
LOS
Interrupt
Enable
R/W
0
BIT 5
AIS
Interrupt
Enable
R/W
0
BIT 4
Idle Interrupt
Enable
R/W
0
BIT 3
FERF
Interrupt
Enable
R/W
0
BIT 2
AIC
Interrupt
Enable
R/W
0
BIT 1
OOF
Interrupt
Enable
R/W
0
BIT 0
P-Bit Error
Interrupt
Enable
R/W
0
Setting this bit-field to “1” enables this interrupt. Con-
versely, setting this bit-field to “0” disables this inter-
rupt.
Servicing the Change of State on Receive OOF In-
terrupt
Whenever the XRT72L56 Framer IC detects this in-
terrupt, it will do all of the following.
• It will assert the Interrupt Request output pin (INT)
by driving this pin "Low".
• It will set Bit 1 (OOF Interrupt Status), within the
RxDS3 Interrupt Status Register to “1”, as indicated
below.
RXDS3 INTERRUPT STATUS REGISTER (ADDRESS = 0X13)
BIT 7
CP-Bit Error
Interrupt
Status
RUR
0
BIT 6
LOS
Interrupt
Status
RUR
0
BIT 5
AIS
Interrupt
Status
RUR
0
BIT 4
Idle Interrupt
Status
RUR
0
BIT 3
FERF
Interrupt
Status
RUR
0
BIT 2
AIC
Interrupt
Status
RUR
0
BIT 1
OOF
Interrupt
Status
RUR
1
BIT 0
P-Bit Error
Interrupt
Status
RUR
0
Whenever the Terminal Equipment encounters a
Change in OOF on Receive Interrupt, then it should
do the following.
1. It should determine the current state of the OOF
condition. Recall, that this interrupt can gener-
ated, whenever the XRT72L56 Framer declares
or clears the OOF defects. Hence, the user can
determine the current state of the OOF defect by
reading the state of Bit 4 (RxOOF), within the
RxDS3 Configuration & Status Registers, as illus-
trated below.
RXDS3 CONFIGURATION & STATUS REGISTER (ADDRESS = 0X10)
BIT 7
RxAIS
RO
0
BIT 6
RxLOS
RO
0
BIT 5
RxIdle
RO
0
BIT 4
RxOOF
RO
0
BIT 3
Reserved
RO
0
BIT 2
Framing On
Parity
RO
0
BIT 1
FSync
Algo
RO
0
BIT 0
MSync
Algo
RUR
0
If OOF is TRUE.
1. It should transmit a FERF (Far-End Receive Fail-
ure) to the Remote Terminal Equipment. The
XRT72L56 Framer IC automatically supports this
action via the FERF-upon-OOF 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 OOF is FALSE
1. It should cease transmitting a FERF (Far-End
Receive Failure) indicator to the Remote Terminal
Equipment. The XRT72L56 Framer IC automati-
cally supports this action via the FERF-upon-
OOF feature.
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