XRT72L50 Datasheet, PDF (117/471 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
Setting this bit-field to "1" configures the Transmit Section of the Channel to use the Input Interface as the
source for the FAS pattern.
NOTE: For more information on the FAS pattern, refer to Section 5.1.
2.3.7.2 Transmit E3 LAPD Configuration Register (ITU-T G.751)
TxE3 LAPD Configuration Register (Address = 0x33)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Not Used
Auto Retrans- Not Used
mit
TxLAPD
Msg Length
TxLAPD
Enable
RO
RO
RO
RO
R/W
RO
R/W
R/W
0
0
0
0
1
0
0
0
Bit 3 - Auto Retransmit
This Read/Write bit-field permits 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 has 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 permits 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 E3 frames, to the Remote Terminal.
Writing a "0" disables the LAPD Transmitter (default condition). Writing a "1" enables the LAPD Transmitter.
NOTE: For information on the LAPD Transmitter, refer to Section 5.2.3.
2.3.7.3 Transmit E3 LAPD Status and Interrupt Register (ITU-T G.751)
TxE3 LAPD Status and Interrupt Register (Address = 0x34)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Not Used
TXDL Start TXDL Busy
TxLAPD
Interrupt
Enable
TxLAPD
Interrupt
Status
RO
RO
RO
RO
R/W
RO
R/W
RUR
0
0
0
0
0
0
0
0
Bit 3 - TxDL Start
This Read/Write bit-field permits the user to command the LAPD Transmitter to do the following.
• Read in the PMDL Header and Message from the Transmit LAPD Message Buffer. (80 or 86 bytes)
104