
XRT7250
DS3/E3 FRAMER IC
á
REV. 1.1.1
228
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 "High".
It will set Bit 3 (FERF Interrupt Status), within the
Rx DS3 Interrupt Status Register, to “1”, as indi-
cated below.
Whenever the Terminal Equipment encounters a
Change in FERF Condition on Receive Interrupt, it
should do the following.
1. It should determine the current state of the FERF
condition. Recall, that this interrupt can gener-
ated, whenever the XRT7250 Framer declares or
clears the FERF condition. Hence, the user can
determine the current state of the FERF condition
by reading the state of Bit 5 (RxIdle), within the
RxDS3 Configuration & Status Registers, as illus-
trated below
4.3.6.2.6
The Change of State of Receive AIC
Interrupt
If the Change of State of Receive AIC Interrupt is en-
abled, then the XRT7250 Framer IC will generate an
interrupt, anytime the Receive DS3 Framer block has
detected a change in the value of the AIC bit, within
the incoming DS3 data stream.
Enabling and Disabling the Change of State of
Receive AIC Interrupt:
The user can enable or disable the Change of State
on Receive AIC Interrupt, by writing the appropriate
value into Bit 2 (AIC Interrupt Enable) within the
RxDS3 Interrupt Enable Register, as illustrated 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 of State on Receive AIC In-
terrupt
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 "High".
It will set Bit 3 (AIC Interrupt Status), within the Rx
DS3 Interrupt Status Register, to “1”, as indicated
below.
RXDS3 INTERRUPT STATUS REGISTER (ADDRESS = 0X13)
BIT 7BIT 6BIT 5BIT 4BIT 3BIT 2BIT 1BIT 0
CP-Bit Error
Interrupt
Status
LOS
Interrupt
Status
AIS
Interrupt
Status
Idle Interrupt
Status
FERF
Interrupt
Status
AIC
Interrupt
Status
OOF
Interrupt
Status
P-Bit Error
Interrupt
Status
RURRUR
RUR
RURRUR
00
001
000
RXDS3 STATUS REGISTER (ADDRESS = 0X11)
BIT 7BIT 6BIT 5BIT 4BIT 3BIT 2BIT 1BIT 0
Reserved
RxFERF
RxAIC
RxFEBE[2:0]
RO
00
000
RXDS3 INTERRUPT ENABLE REGISTER (ADDRESS = 0X12)
BIT 7BIT 6BIT 5BIT 4BIT 3BIT 2BIT 1BIT 0
CP Bit Error
Interrupt
Enable
LOS
Interrupt
Enable
AIS
Interrupt
Enable
Idle Interrupt
Enable
FERF
Interrupt
Enable
AIC
Interrupt
Enable
OOF
Interrupt
Enable
P-Bit Error
Interrupt
Enable
R/W
00
000