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XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER
REV. 1.2.1
334
Enabling and Disabling the Change of Framing Alignment Interrupt
The user can enable or disable the Change of Framing Alignment Interrupt by writing the appropriate value into
Bit 4 (COFA Interrupt Enable), within the Rx E3 Interrupt Enable Register - 1.
Writing a “1” into this bit-field enables the Change of Framing Alignment Interrupt. Conversely, writing a “0” into
this bit-field disables the Change of Framing Alignment Interrupt.
Servicing the Change of Framing Alignment Interrupt
Whenever the XRT72L50 Framer IC generates this interrupt, it will do the following.
It will assert the Interrupt Request output pin (Int) by driving it "Low".
It will set Bit 4 (COFA Interrupt Status), within the Rx E3 Interrupt Status Register -1, to “1”, as indicated
below.
5.3.6.2.6
The Change in Receive FERF Condition Interrupt
If the Change in Receive FERF Condition Interrupt is enabled, then the XRT72L50 Framer IC will generate an
interrupt in response to either of the following conditions.
1. When the XRT72L50 Framer IC declares a FERF (Far-End Receive Failure) Condition, and
2. When the XRT72L50 Framer IC clears the FERF condition.
Conditions causing the XRT72L50 Framer IC to declare an FERF Condition.
If the XRT72L50 Framer IC begins receiving E3 frames which have the A bit set to “1”).
Conditions causing the XRT72L50 Framer IC to clear the AIS Condition.
If the XRT72L50 Framer IC begins receiving E3 frames that do NOT have the A bit set to “1”.
RxE3 Interrupt ENABLE Register - 1 (Address = 0x12)
BIT 7BIT 6BIT 5
BIT 4BIT 3BIT 2BIT 1BIT 0
Not Used
COFA
Interrupt
Enable
OOF
Interrupt
Enable
LOF
Interrupt
Enable
LOS
Interrupt
Enable
AIS
Interrupt
Enable
RO
R/WR/W
R/W
00
0
X
0
000
RxE3 Interrupt Status Register - 1 (Address = 0x14)
BIT 7BIT 6BIT 5
BIT 4BIT 3BIT 2BIT 1BIT 0
Not Used
COFA
Interrupt
Status
OOF
Interrupt
Status
LOF
Interrupt
Status
LOS
Interrupt
Status
AIS
Interrupt
Status
RO
RUR
00
0
10
000