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XRT7250
DS3/E3 FRAMER IC
REV. 1.1.1
435
Writing a “1” into this bit-field enables the Change in
Trail Trace Buffer Message Interrupt. Conversely,
writing a “0” into this bit-field disables the Change in
Trail Trace Buffer Message Interrupt.
Servicing the Change in Trail Trace Buffer Mes-
sage 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 6 (TTB Change Interrupt Status),
within the Rx E3 Interrupt Status Register - 2, as
indicated below.
It will write the contents of this newly received Trail
Trace Buffer Message, into the RxTTB-0 (located at
0x1C) through RxTTB-15 (located at 0x2B) regis-
ters.
Whenever the Terminal Equipment encounters the
Change in Trail Trace Buffer Message Interrupt, then
it should read out the contents of the 16 RxTTB regis-
ters.
6.3.6.2.7
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 FERF bit (within the MA
byte, 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 FERF 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
the RxE3 Interrupt Enable Register - 2, as indicated
below.
Setting this bit-field to “1” enables this interrupt. Con-
versely, setting this bit-field to “0” disables this inter-
rupt.
Servicing the Change in Receive FERF Condition
Interrupt
Whenever the XRT7250 Framer IC detects this inter-
rupt, it will do all of the following.
It will assert the Interrupt Request output pin (INT),
by driving it “Low”.It will set Bit 3 (FERF Interrupt
RXE3 INTERRUPT STATUS REGISTER - 2 (ADDRESS = 0X15)
BIT 7BIT 6BIT 5BIT 4BIT 3BIT 2BIT 1BIT 0
Not Used
TTB
Change
Interrupt
Status
Not Used
FEBE
Interrupt
Status
FERF
Interrupt
Status
BIP-8
Error Interrupt
Status
Framing
Byte Error
Interrupt
Status
RxPld
Mis
Interrupt
Status
RO
RUR
RO
RUR
0
1000
000
RXE3 INTERRUPT ENABLE REGISTER - 2 (ADDRESS = 0X13)
BIT 7BIT 6BIT 5BIT 4BIT 3BIT 2BIT 1BIT 0
Not Used
TTB
Change
Interrupt
Enable
Not Used
FEBE
Interrupt
Enable
FERF
Interrupt
Enable
BIP-8
Error Interrupt
Enable
Framing
Byte Error
Interrupt
Enable
RxPld
Mis
Interrupt
Enable
RO
R/W
RO
R/W
0
000
X
000