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XRT7250
DS3/E3 FRAMER IC
REV. 1.1.1
327
tion, it will still rely on the old framing alignment for E3
payload data extraction, etc.
However, if the Receive E3 Framer had to change
alignment, in order to re-acquire frame synchroniza-
tion, then this interrupt will occur.
Enabling and Disabling the Change of Framing
Alignment Interrupt
The user can enable or disable the Change of Fram-
ing Alignment Interrupt by writing the appropriate val-
ue 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 Inter-
rupt
Whenever the XRT7250 Framer IC generates this in-
terrupt, 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 indi-
cated below.
5.3.6.2.6
The Change in Receive FERF Condi-
tion Interrupt
If the Change in Receive FERF Condition Interrupt is
enabled, then the XRT7250 Framer IC will generate
an interrupt in response to either of the following con-
ditions.
1. When the XRT7250 Framer IC declares a FERF
(Far-End Receive Failure) Condition, and
2. When the XRT7250 Framer IC clears the FERF
condition.
Conditions causing the XRT7250 Framer IC to de-
clare an FERF Condition.
If the XRT7250 Framer IC begins receiving E3
frames which have the “A” bit set to “1”).
Conditions causing the XRT7250 Framer IC to
clear the AIS Condition.
If the XRT7250 Framer IC begins receiving E3
frames that do NOT have the “A” bit set to “1”.
Enabling and Disabling the Change in Receive
AIS Condition Interrupt
The user can enable or disable the Change in Re-
ceive FERF Condition Interrupt, by writing the appro-
priate value into Bit 3 (FERF Interrupt Enable), within
RXE3 INTERRUPT ENABLE REGISTER - 1 (ADDRESS = 0X12)
BIT 7BIT 6BIT 5BIT 4BIT 3BIT 2BIT 1BIT 0
Not Used
COFA
Interrupt
Enable
OOF
Interrupt
Enable
LOF
Interrupt
Enable
LOS
Interrupt
Enable
AIS
Interrupt
Enable
RO
R/W
00
0
X
00
0
RXE3 INTERRUPT STATUS REGISTER - 1 (ADDRESS = 0X14)
BIT 7BIT 6BIT 5BIT 4BIT 3BIT 2BIT 1BIT 0
Not Used
COFA
Interrupt
Status
OOF
Interrupt
Status
LOF
Interrupt
Status
LOS
Interrupt
Status
AIS
Interrupt
Status
RO
RUR
0
0010
000