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XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER
REV. 1.2.1
54
Bit 4 - RxOOF (Receive Out-of-Frame) Indicator
This Read-Only bit-field indicates whether or not the Receive Section of the channel is currently declaring an
OOF condition.
If this bit-field is set to "0", then the Receive Section is currently not declaring the OOF condition.
If this bit-field is set to "1", then the Receive Section is currently declaring the OOF condition.
N
OTE
:
For more information on the OOF Declaration criteria, for DS3 applications, refer to
Section 4.3.2.2
.
Bit 3 - Reserved
Bit 2 - Framing On Parity ON/OFF Select
This Read/Write bit field allows the user to require that the Receive DS3/E3 Framer block include Parity (P-bit)
verification as a condition for declaring itself In-Frame during Frame Acquisition. This requirement will be
imposed in addition to those criteria selected via Bits 0 and 1 of this register.
This feature also imposes an additional Frame Maintenance requirement on the Receive DS3/E3 Framer block,
in addition to the requirements specified in the user's selection of Bits 0 and 1 of this register. In particular, if
this additional requirement is implemented, the Receive DS3/E3 Framer block will perform a frame search if it
detects P-bit errors in at least 2 out of 5 DS3 Frames. Writing a "1" to this bit-field imposes these additional
requirements. Whereas, writing a '0' causes the Receive DS3/E3 Framer block to waive this requirement.
N
OTE
:
For more information on Framing with Parity, refer to
Section 4.3.2.2
.
Bit 1 - F Sync Algo(rithim Select)
This Read/Write bit-field, in conjunction with Bits 0 and 2 of this register, allows the user to completely define
the Frame Maintenance Criteria of the Receive DS3/E3 Framer block. This particular bit-field allows the user
to define the Frame Maintenance Criteria as it applies to F-bits.
If the user writes a "1" to this bit-field, then the Receive DS3/E3 Framer block will declare an Out of Frame
(OOF) condition if 3 out of 16 F-Bits are in Error. If the user writes a "0" to this bit-field, then the Receive DS3/
E3 Framer block will declare an Out of Frame (OOF) condition if 6 out of 16 F-bits are in error.
N
OTE
:
For more information on the use of this bit, and the Framing Maintenance operation of the Receive DS3/E3 Framer
block, refer to
Section 4.3.2.2
.
Bit 0 - M Sync Algo(rithm Select)
This Read/Write bit-field in conjunction with Bits 1 and 2 of this register, allows the user to completely define
the Frame Maintenance Criteria of the Receive DS3/E3 Framer block. This particular bit-field allows the user
to define the Frame Maintenance criteria, as it applies to M-bits.
If the user writes a "1" to this bit-field, then the Receive DS3/E3 Framer block will declare an Out of Frame
(OOF) condition if 3 out of 4 M-bits are in error. If the user writes a "0" to this bit-field, then the Receive DS3/E3
Framer block will ignore the occurrence of M-bit errors while operating in the Frame Maintenance mode.
N
OTE
:
For more information on the use of this bit-field, and the Framing Maintenance operation of the Receive DS3/E3
Framer block, refer to
Section 4.3.2.2
.
2.3.2.9
Receive DS3 Status Register
Bit 4 - RxFERF Indicator
This Read Only bit-field indicates whether or not the Receive Section of the channel is declaring a FERF (Far-
End-Receive Failure) condition.
RxDS3 Status Register (Address = 0x11)
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
Reserved
RxFERF
RxAIC
RxFEBE[2:0]
RO
RO
RO
RO
RO
RO
RO
RO
0
0
0
1
0
0
0
0