XRT72L50 Datasheet, PDF (99/471 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
Bit 0 - TxFEAC Busy
This Read-Only bit-field allows the local µP to poll and determine if the Transmit FEAC Processor has
completed its 10th transmission of the 16-bit FEAC Message. This bit-field will contain a "1", if the Transmit
FEAC Processor is still transmitting the FEAC Message. This bit-field will toggle to "0", once the Transmit
FEAC Processor has completed its 10th transmission of the FEAC Message.
NOTE: For more information on the Transmit FEAC Processor, refer to Section 4.2.3.1.
2.3.5.3 Transmit DS3 FEAC Register
TxDS3 FEAC RegisTer (Address = 0x32)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Not Used
TxFEAC[5:0]
Not Used
RO
R/W
R/W
R/W
R/W
R/W
R/W
RO
0
1
1
1
1
1
1
0
This register contains a six (6) bit read/write field that allows the user to write in the six-bit FEAC code word,
that is desired to be transmitted to the Far End Receive FEAC Processor, via the outgoing DS3 data stream.
The Transmit FEAC Processor will encapsulate this six-bit code into a 16-bit FEAC message, and will proceed
to transmit this message to the Remote Receiver via the FEAC bit-field within each out-going DS3 frame.
NOTE: For more information on the operation of the Transmit FEAC Processor, refer to Section 4.2.3.1.
2.3.5.4 Transmit DS3 LAPD Configuration Register
TxDS3 LAPD Configuration Register (Address = 0x33)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Not Used
Auto
Retransmit
Not Used TxLAPD Msg
Length
TxLAPD
Enable
RO
RO
RO
RO
R/W
R/W
R/W
R/W
0
0
0
0
1
0
0
0
Bit 3 - Auto Retransmit
This Read/Write bit-field allows the user to configure the LAPD Transmitter to either transmit the LAPD
Message frame only once or, repeatedly at one-second intervals.
Writing a "0" to this bit-field configures the LAPD Transmitter to transmit the LAPD Message frame once.
Afterwards, the LAPD Transmitter will halt transmission, until it is commanded to transmit another LAPD
Message frame.
Writing a "1" to this bit-field configures the LAPD Transmitter to transmit the LAPD Message frame repeatedly
at One-Second intervals. In this configuration, the LAPD Transmitter will repeat its transmission of the LAPD
Message frame until it has been disabled.
Bit 1 - TxLAPD Message Length Select
This Read/Write bit-field permits the user to select the length of the outbound LAPD Message frame.
Setting this bit-field to "0" configures the outbound LAPD Message frame to be 76 bytes in length. Setting this
bit-field to “1” configures the outbound LAPD Message frame to be 82 bytes in length.
NOTE: This should match with the message type of the LAPD message to be sent. (See Table 21 .)
Bit 0 - TxLAPD Enable
This Read/Write bit-field allows the user to enable or disable the LAPD Transmitter. The LAPD Transmitter
must be enabled before it can be commanded to transmit a LAPD Message frame (containing a PMDL
message) via the outbound DS3 frames, to the Far-End Terminal.
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