XRT72L50 Datasheet, PDF (103/471 Pages) Exar Corporation – SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER
REV. 1.2.1
exists in these bit-fields, this will result in a change of state for the corresponding F-bit, prior to being
transmitted to the Remote Terminal Equipment.
If the Transmit DS3/E3 Framer block is to be operated in the normal mode (e.g., when no errors are being
injected into these F-bit fields of the outbound DS3 frames), then all of these bit-fields must be "0’s".
2.3.5.10 Transmit F-Bit Mask Register 4
TxDS3 F-Bit Mask Register 4 (Address = 0x39)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
FBit Mask[7] FBit Mask[6] FBit Mask[5] FBit Mask[4] FBit Mask[3] FBit Mask[2] FBit Mask[1] FBit Mask[0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bits 7 - 0 F-Bit Mask[7:0]
These Read/Write bit-fields allow the user to insert errors into the last eight F-bits of a DS3 M-frame, for test
and diagnostic purposes. The Transmit DS3/E3 Framer block automatically performs an XOR operation on the
actual contents of these F-bit fields to these register bit-fields. Therefore, for every "1" that exists in these bit-
fields, this will result in a change of state for the corresponding F-bit, prior to being transmitted to the Remote
Terminal Equipment.
If the Transmit DS3/E3 Framer block is to be operated in the normal mode (e.g., when no errors are being
injected into these F-bit fields of the outbound DS3 frames), then all of these bit-fields must be "0’s".
2.3.6 Transmit E3 (ITU-T G.832) Configuration Registers
2.3.6.1 Transmit E3 Configuration Register (E3, ITU-T G.832)
TxE3 Configuration Register (Address = 0x30)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Not Used
TxDL
in NR
Not Used
TxAIS
Enable
TxLOS
Enable
TxMARx
RO
RO
RO
R/W
RO
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Bit 4 - DLinNR
This Read/Write bit-field permits the user to specify whether the LAPD Transmitter should insert the outbound
LAPD Message frame octets into the NR byte-field, or in the GC-byte-field, within each outbound E3 frame.
Writing a "1" configures the LAPD Transmitter to insert the octets of the outbound LAPD Message frame into
the NR byte-field, within each outbound E3 frame. Writing in "0" configures the LAPD Transmitter to insert the
octets of the outbound LAPD Message frame into the GC byte-field, within each outbound E3 frame.
Bit 2 - TxAIS Enable
This Read/Write bit-field allows the user to command the Transmit E3 Framer to transmit an AIS pattern, upon
demand.
Writing a "0" to this bit-field allows the Transmit DS3/E3 Framer block to transmit internally generated data
(e.g., the ITU-T G.832 compatible E3 frames with the E3 payload data) to the Remote Terminal. Writing a "1"
to this bit-field causes the Transmit DS3/E3 Framer block to transmit an all "1’s" pattern to the Remote
Terminal.
NOTE: If the Transmit DS3/E3 Framer block is transmitting an AIS pattern to the Remote Terminal, then it is not transmitting
any E3 frames. Consequently, if this command is invoked, the Remote Terminal will experience an OOF (Out of
Frame) condition.
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