XRT7250 Datasheet, PDF (86/463 Pages) Exar Corporation – DS3/E3 FRAMER IC

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DS3/E3 FRAMER IC
XRT7250
REV. 1.1.1
Bit 3 - RxTMark Algorithm
This Read/Write bit-field allows the user to select the
number of consecutive incoming E3 frames, that the
Timing Marker bit-field (within the MA byte-field) must
be of a given logic state, before it is validated by the
Receive E3 Framer. Once the Receive E3 Framer
has validated the state of the Timing Marker bit-field,
then it will write this logic state into Bit 1 (RxTMark)
within the Rx E3 Configuration & Status Register 2
(Address = 0x11)
Writing a "0" into this bit-field causes the Receive E3
Framer to validate the Timing Marker value after re-
ceiving 3 consecutive incoming E3 frames, with the
Timing Marker bit-field of a given value. Writing a "1"
into this bit-field causes the Receive E3 Framer to
validate the Timing Marker value after receiving 5
consecutive incoming E3 frames, with the Timing
Marker bit-field of a given value.
Bits 2 - 0: RxPLDExp[2:0]
This Read/Write bit-field allows the user to specify the
Payload Type that is expected in the MA bytes, of
each incoming E3 frame.
If the Receive E3 Framer detects a Payload Type that
differs from the values within these bit-fields, then the
Framer will generate the Payload Type Mismatch in-
terrupt.
2.3.3.2 Receive E3 Configuration & Status
Register 2 (E3, ITU-T G.832)
RXE3 CONFIGURATION & STATUS REGISTER 2 (ADDRESS = 0X11)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Rx LOF Algo RxLOF
RxOOF
RxLOS
RxAIS RxPld Unstab RxTMark
RxFERF
R/W
RO
RO
RO
RO
RO
RO
RO
0
1
1
1
1
1
1
1
Bit 7 - RxLOF Algo (Loss of Frame Declaration Al-
gorithm)
This Read/Write bit-field allows the user to select the
LOF (Loss of Frame) Declaration criteria, that will be
used by the Receive E3 Framer. Writing a "0" to this
bit-field configures the Receive E3 Framer to declare
an LOF condition, after it has been in the OOF condi-
tion for 24 frame periods (3 ms). Writing a "1" to this
bit-field configures the Receive E3 Framer to declare
an LOF condition, after it has been in the OOF condi-
tion for 8 frame periods (1 ms).
Bit 6 - RxLOF (Loss of Frame Declaration)
This Read-Only bit-field indicates whether or not the
Receive E3 Framer is currently in the Loss of Frame
(LOF) condition. If this bit-field is set to "1", then the
Receive E3 Framer is currently in the LOF condition.
Conversely, if this bit-field is set to "0", then the Re-
ceive E3 Framer is currently not in the LOF condition.
Bit 5 - RxOOF (Out of Frame Declaration)
This Read-Only bit field indicates whether or not the
Receive E3 Framer is currently experiencing an Out
of Frame (OOF) condition. The Receive E3 Framer
will declare an OOF condition if it has detected errors
in the frame alignment bytes (FA1 and FA2) in four
consecutive frames. If this bit-field is set to "1", then
the Receive E3 Framer has declared, and is continu-
ing to experience an OOF condition. If this bit-field is
set to "0", then the Receive E3 Framer is currently not
experiencing an OOF condition.
Bit 4 - RxLOS (Loss of Signal Declaration)
This Read-Only bit-field indicates whether or not the
Receive E3 Framer is currently experiencing a Loss
of Signal (LOS) condition. The Receive E3 Framer
will declare an LOS condition if it has detected a
string of 32 consecutive "0’s", via the RxPOS and Rx-
NEG input pins. If this bit-field is set to "1", then the
Receive E3 Framer has declared, and is continuing to
experience an LOS condition. If this bit-field is set to
"0", then the Receive E3 Framer is currently not expe-
riencing an LOS condition.
Bit 3 - RxAIS (Alarm Indication Status Declara-
tion)
This Read-Only bit-field indicates whether or not the
Receive E3 Framer is currently experiencing an AIS
condition. The Receive E3 Framer will declare an
AIS condition if it has detected two consecutive E3
frames, that each contain less than seven (7) "0’s" . If
this bit-field is set to "1", then the Receive E3 Framer
has declared, and is continuing to experience an AIS
condition. If this bit-field is set to "0", then the Re-
ceive E3 Framer is currently not experiencing an AIS
condition.
Bit 2 - RxPLDType UnStab
This Read-Only bit-field indicates whether or not the
Receive E3 Framer has been receiving a consistent
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