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XRT79L71
PRELIMINARY
93
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
TABLE 15: HOW THE TRANSMIT DS3 FRAMER BLOCK INTERNALLY GENERATES EACH OF THE OVERHEAD BITS - C-
BIT PARITY APPLICATIONS
BIT NAME
BIT DESCRIPTION
HOW THE OVERHEAD BIT IS INTERNALLY GENERATED BY THE TRANSMIT
DS3 FRAMER BLOCK
X-Bits (2)
FERF/Yellow Alarm Indicator
Bits
Either Software Controlled or automatically set to "0" whenever the cor-
responding Receive DS3 Framer block declares the LOS, LOF/OOF or
AIS defect condition.
F1 Bits (14)
F-Frame Framing Alignment
bits that are of the value "1"
Set to the value of "1".
F0 Bits (14)
F-Frame Framing Alignment
bits that are of the value "0".
Set to the value of "0".
M1 Bit (1)
M-Frame Framing Alignment
bits that are of the value "1
Set to the value of "1".
M0 Bits (2)
M-Frame Framing Alignment
bits that are of the value "0"
Set to the value of "0".
P-bits (2)
Parity Bits
Transmit DS3 Framer block computes the even parity value over the
payload bits within a given DS3 frame. The results of this calculation are
inserted into the two P-bit positions within the very next DS3 frame.
CP-bits (3)
Path Parity Bits
Transmit DS3 Framer block computes the even parity value over the
payload bits within a given DS3 frame. The results of this calculation are
inserted into the three CP-bit positions within the very next DS3 frame.
AIC bit (1)
Application Identical Channel
Set to the value "1" in order to denote C-bit Parity framing format.
UDL bits (9)
User Data Link Bits
Set to the value "1".
DL bits (3)
Path Maintenance Data Link
(PMDL) bits
These bits carry the PMDL/LAPD Message that is generated by the
LAPD Transmitter within the Transmit Section of the XRT79L71.
However, if the Transmit LAPD Controller block is not being used, then
these bits will each be set to "1".
FEAC bit (1)
Far-End Alarm & Control Bit
This bit carries the FEAC Message that is generated by the Transmit
FEAC Processor within the Transmit Section of the XRT79L71.
However, if the Transmit FEAC Controller Block is not being used, then
this bit will be set to "1"
FEBE bits (3)
Far-End Block Error Bits
These bits are set to [1, 1, 1] whenever the corresponding Receive DS3
Framer block detects no CP nor framing F and M bit errors within its
incoming DS3 data-stream. These bits are set to values other than [1, 1,
1] whenever the corresponding Receive DS3 Framer block detects CP
or framing bit errors within its incoming DS3 data-stream.
NOTE: These bit-fields can also be software-controlled.