
XRT7250
á
DS3/E3 FRAMER IC
REV. 1.1.1
430
Whenever the user’s system encounters the Change
in Receive LOS Condition Interrupt, then it should do
the following.
1. It should determine the current state of the LOS
condition. Recall, that this interrupt can be gen-
erated, whenever the XRT7250 Framer IC
declares or clears the LOS defect. Hence, the
user can determine the current state of the LOS
defect by reading the state of Bit 4 (RxLOS)
within the Rx E3 Configuration and Status Regis-
ter - 2, as illustrated below.
If the LOS state is TRUE
1. It should transmit a FERF (Far-End-Receive Fail-
ure) indicator to the Remote Terminal Equipment.
The XRT7250 Framer IC automatically supports
this action via the FERF-upon-LOS feature.
If the LOS state is FALSE
1. It should cease transmitting the FERF indication
to the Remote Terminal Equipment. The
XRT7250 Framer IC automatically supports this
action via the FERF-upon-LOS feature.
6.3.6.2.2
The Change in Receive OOF Condi-
tion Interrupt
If the Change in Receive OOF 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 OOF
(Out of Frame) Condition, and
2. When the XRT7250 Framer IC clears the OOF
condition.
Conditions causing the XRT7250 Framer IC to de-
clare an OOF Condition.
If the Receive E3 Framer block (within the XRT7250
Framer IC) detects Framing Byte errors, within four
consecutive incoming E3 frames.
Conditions causing the XRT7250 Framer IC to
clear the OOF Condition.
If the Receive E3 Framer block (within the XRT7250
Framer IC) transitions from the FA1, FA2 Octet Ver-
ification state to the In-Frame state (see Figure
175).
If the Receive E3 Framer block transitions from the
OOF Condition state to the In-Frame state (see Fig-
ure 175).
Enabling and Disabling the Change in Receive
OOF Condition Interrupt
The user can enable or disable the Change in Re-
ceive OOF Condition Interrupt, by writing the appro-
priate value into Bit 3 (OOF Interrupt Enable), within
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
00
000
010
RXE3 CONFIGURATION & STATUS REGISTER 2 (ADDRESS = 0X11)
BIT 7BIT 6BIT 5BIT 4BIT 3BIT 2BIT 1BIT 0
Rx LOF Algo
RxLOF
RxOOF
RxLOS
RxAIS
RxPld Unstab
Rx
TMark
RxFERF
R/W
RORO
RO
RORORORO
XX
XXXX
XX