XRT72L52 Datasheet, PDF (399/480 Pages) Exar Corporation – TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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PRELIMINARY
XRT72L52
TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. P1.1.3
within the Tx E3 Configuration Register, as depicted ⁾
below.
TXE3 CONFIGURATION REGISTER (ADDRESS = 0X30)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
Not Used
TxDL
in NR
Not Used
RO
RO
RO
R/W
RO
0
0
0
0
0
BIT 2
TxAIS
Enable
R/W
0
BIT 1
TxLOS
Enable
R/W
0
BIT 0
TxMARx
R/W
0
If the user writes a “0” into this bit-field, then the
LAPD Transmitter will transmit the comprising octets
of the Outbound LAPD Message frame via the GC
byte field. Additionally, the Transmit E3 Framer block
will insert the contents of the TxNR Byte Register
(Address = 0x37) into the “NR” byte of each Out-
bound E3 frame.
Conversely, if the user writes a “1” into this bit-field,
then the LAPD Transmitter will transmit the Outbound
LAPD Message frame octets via the NR byte-field,
within each Outbound E3 frame. Additionally, the
Transmit E3 Framer will insert the contents of the Tx
GC Byte Register (Address = 0x35) into the GC byte-
field of each Outbound E3 frame.
STEP 5 - Specify whether the LAPD Transmitter
should transmit the LAPD Message frame only
once, or an indefinite number of times at One-
Second intervals.
The Transmit E3 HDLC Control block allows the user
to configure the LAPD Transmitter to transmit this
LAPD Message frame only once, or an indefinite
number of times at One-Second intervals. The user
implements this configuration by writing the appropri-
ate value into Bit 3 (Auto Retransmit) within the Tx E3
LAPD Configuration Register (Address = 0x33), as
depicted below.
)
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
Retransmit
Not Used
TxLAPD
Msg Length
TxLAPD
Enable
RO
RO
RO
RO
R/W
RO
R/W
R/W
0
0
0
0
1
0
0
0
If the user writes a “1” into this bit-field, then the
LAPD Transmitter will transmit the LAPD Message
frame repeatedly at One-Second intervals until the
LAPD Transmitter is disabled.
If the user writes a “0” into this bit-field, then the
LAPD Transmitter will transmit the LAPD Message
frame only once. Afterwards, the LAPD Transmitter
will halt its transmission until the user invokes the
Transmit LAPD Message frame command, once
again.
STEP 6 - Enabling the LAPD Transmitter
Prior to the transmission of any data via the LAPD
Transmitter, the LAPD Transmitter must be enabled
by writing a "1" to bit 0 (TxLAPD Enable) of the Tx E3
LAPD Configuration Register, as depicted below.
TRANSMIT E3 LAPD CONFIGURATION REGISTER (ADDRESS = 0X33)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT2
BIT 1
BIT 0
Not Used
Auto
Retransmit
Not Used
TxLAPD
Msg Length
TxLAPD
Enable
R/O
R/O
R/O
R/O
R/W
R/O
R/W
R/W
0
0
0
0
X
0
X
X
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