
á
XRT7250
DS3/E3 FRAMER IC
REV. 1.1.1
433
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 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 -2, to “1”, as indi-
cated below.
6.3.6.2.5
The Change in Receive AIS Condition
Interrupt
If the Change in Receive AIS 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 an AIS
(Loss of Signal) Condition, and
2. When the XRT7250 Framer IC clears the AIS
condition.
Conditions causing the XRT7250 Framer IC to de-
clare an AIS Condition.
If the XRT7250 Framer IC detects 7 or less “0”
within 2 consecutive E3 frames.
Conditions causing the XRT7250 Framer IC to
clear the AIS Condition.
If the XRT7250 Framer IC detects 2 consecutive E3
frames that each contain 8 or more “0’s”.
Enabling and Disabling the Change in Receive
AIS Condition Interrupt
The user can enable or disable the Change in Re-
ceive LOS Condition Interrupt, by writing the appro-
priate value into Bit 0 (AIS Interrupt Enable), within
the RxE3 Interrupt Enable Register - 1, as indicated
below.
Setting this bit-field to “1” enables this interrupt. Con-
versely, setting this bit-field to “0” disables this inter-
rupt.
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
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
0
0000
0
X
0