XRT72L56 Datasheet, PDF (130/486 Pages) Exar Corporation – SIX CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L56 SIX CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. P1.1.2
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PRELIMINARY
TXE3 TTB-0 REGISTER (ADDRESS = 0X38)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
TxTTB0[7:0]
R/W
R/W
R/W
R/W
R/W
1
0
0
1
0
BIT 2
R/W
0
BIT 1
R/W
0
BIT 0
R/W
0
This Read/Write byte-field, along with the Tx TTB-1
through Tx TTB-15 registers permit a user to define a
Trail Access Point Identifier sequence of bytes, that
will be transmitted to the Remote Terminal. The Re-
mote Receiving Terminal will use this sequence of
bytes to verify that it is connected to the proper Trans-
mitting Terminal. The Transmit DS3/E3 Framer block
will take the contents of these 16 registers, and insert
them into the TR byte of the outbound E3 frame. In
the first of a set of 16 E3 Frames, the Transmit DS3/
E3 Framer block will read in the contents of this regis-
ter, and insert it into the TR byte-field, within the very
next outbound E3 frame.
This particular byte-field should contain the pattern
"[1, C6, C5, C4, C3, C2, C1, C0]" where the bits C6
through C0 are the results of a CRC-7 calculation
over the previous 16-byte frame.
NOTE: The XRT72L56 Framer IC will not compute this
CRC-7 value. It is up to the user's hardware and/or soft-
ware to compute this value, prior to writing it into this regis-
ter.
2.4.6.8 Transmit E3 TTB-1 Register (E3, ITU-T
G.832)
TXE3 TTB-1 REGISTER (ADDRESS = 0X39)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
TxTTB-1[7:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
This Read/Write byte-field, along with the TxTTB-0
and TxTTB-2 through TxTTB-15 register permit a us-
er to define a Trail Access Point Identifier sequence of
bytes, that will be transmitted to the Remote Terminal.
The Remote Receiving Terminal will use this se-
quence of bytes to verify that it is connected to the
proper Transmitting Terminal. The Transmit DS3/E3
Framer block will take the contents of these 16 regis-
ters, and insert them into the TR byte of the outbound
E3 frame. In the second of a set of 16 E3 Frames,
the Transmit DS3/E3 Framer block will read in the
contents of this register, and insert it into the TR byte-
field, within the very next outbound E3 frame.
The contents of this register, along with Tx TTB-2
through Tx TTB-15 are used to transmit 15 ASCII
characters required for the E.164 numbering format.
2.4.6.9 Transmit E3 TTB-2 Register (E3, ITU-T
G.832)
TXE3 TTB-2 REGISTER (ADDRESS = 0X3A)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
TxTTB-2[7:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
This Read/Write byte-field, along with the TxTTB-0,
TxTTB-1 and TxTTB-3 through TxTTB-15 register
permit a user to define a Trail Access Point Identifier
sequence of bytes, that will be transmitted to the Re-
mote Terminal. The Remote Receiving Terminal will
use this sequence of bytes to verify that it is connect-
ed to the proper Transmitting Terminal. The Transmit
DS3/E3 Framer block will take the contents of these
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