XR72L52 Datasheet, PDF (460/480 Pages) Exar Corporation – TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L52
REV. 1.0.1
xr
TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
The user can enable or disable the Change in Receive LOS Condition Interrupt, by writing the approrpriate val-
ue into Bit 1 (LOS Interrupt Enable), within the RxE3 Interrupt Enable Register - 1, as indicated below.
RXE3 INTERRUPT ENABLE REGISTER - 1 (ADDRESS = 0X12)
BIT 7
BIT 6
Not Used
BIT 5
RO
RO
RO
0
0
0
BIT 4
COFA
Interrupt
Enable
R/W
0
BIT 3
OOF
Interrupt
Enable
R/W
0
BIT 2
LOF
Interrupt
Enable
R/W
0
BIT 1
LOS
Interrupt
Enable
R/W
X
BIT 0
AIS
Interrupt
Enable
R/W
0
Setting this bit-field to “1” enables this interrupt. Conversely, setting this bit-field to “0” disables this interrupt.
Servicing the Change in Receive LOS Condition Interrupt
Whenever the XRT72L52 Framer IC detects this interrupt, it will do all of the following.
• It will assert the Interrupt Request output pin (Int), by driving it "Low".
• It will set Bit 1 (LOS Interrupt Status), within the Rx E3 Interrupt Status Register - 1 to “1”, as indicated below.
RXE3 INTERRUPT STATUS REGISTER - 1 (ADDRESS = 0X14)
BIT 7
BIT 6
Not Used
BIT 5
RO
RO
RO
0
0
0
BIT 4
COFA
Interrupt
Status
RUR
0
BIT 3
OOF
Interrupt
Status
RUR
1
BIT 2
LOF
Interrupt
Status
RUR
0
BIT 1
LOS
Interrupt
Status
RUR
0
BIT 0
AIS
Interrupt
Status
RUR
0
Whenever the user’s system encounters the Change in Receive LOS Condition Interrupt, then it should do the
following.
1. It should determine the current state of the LOS condition. Recall, that this interrupt can be generated,
whenever the XRT72L52 Framer IC declares or clears the LOS defect. Hence, the user can determine the
current state of the LOS defect by reading the state of Bit 4 (RxLOS) within the Rx E3 Configuration and
Status Register - 2, as illustrated below.
RXE3 CONFIGURATION & STATUS REGISTER 2 (ADDRESS = 0X11)
BIT 7
Rx LOF Algo
BIT 6
RxLOF
R/W
RO
X
X
BIT 5
RxOOF
RO
X
BIT 4
RxLOS
RO
X
BIT 3
RxAIS
RO
X
BIT 2
RxPld Unstab
RO
X
BIT 1
Rx
TMark
RO
X
BIT 0
RxFERF
RO
X
If the LOS state is TRUE
1. It should transmit a FERF (Far-End-Receive Failure) indicator to the Remote Terminal Equipment. The
XRT72L52 Framer IC automatically supports this action via the FERF-upon-LOS feature.
If the LOS state is FALSE
1. It should cease transmitting the FERF indication to the Remote Terminal Equipment. The XRT72L52
Framer IC automatically supports this action via the FERF-upon-LOS feature.
6.3.6.2.2 The Change in Receive OOF Condition Interrupt
If the Change in Receive OOF Condition Interrupt is enabled, then the XRT72L52 Framer IC will generate an
interrupt in response to either of the following conditions.
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