XRT72L56 Datasheet, PDF (109/486 Pages) Exar Corporation – SIX CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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SIX CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
PRELIMINARY
XRT72L56
REV. P1.1.2
This Read-Only register contains the value of the GC
byte, residing in the most recently received E3 frame.
Please see Section 5.3.3 for a more detailed discus-
sion on this register.
2.4.3.11 Receive E3 TTB-0 Register (E3, ITU-T
G.832)
RXE3 TTB-0 REGISTER (ADDRESS = 0X1C)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
RxTTB-0
RO
RO
RO
RO
RO
RO
RO
RO
0
0
0
0
0
0
0
0
This Read-Only register contains the frame start
marker byte of the 16 byte Trail Trace Buffer Message
that has been received from the Remote Terminal, via
the TR byte-field within the incoming E3 frames. The
remaining bytes, of this Trail Trace Buffer Message
can be found in the RxTTB-1 through RxTTB-15 reg-
isters.
The data in this register is typically of the form [1, C6,
C5, C4, C3, C2, C1, C0]. The "1" in the MSB position
identifies this byte as being the frame start marker
(e.g., the first byte within the 16 byte Trail Trace Buffer
Message). The remaining bits: C0 - C6 contain the
CRC-7 value that was calculated over the previous 16
byte Trail Trace Buffer Message.
NOTES:
1. The XRT72L56 Framer device will not compute or
verify this CRC-7 value. It is up to the user's hard-
ware and/or software to compute and verify this
value.
2. For more information on the use of this register,
please see Section 5.3.2.9.
2.4.3.12 Receive E3 TTB-1 Register (E3, ITU-T
G.832)
RXE3 TTB-1 REGISTER (ADDRESS = 0X1D)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
RxTTB-1
RO
RO
RO
RO
RO
RO
RO
RO
0
0
0
0
0
0
0
0
This Read-Only register contains the second (2nd)
byte within the 16 byte Trail Trace Buffer Message,
that has been received from the Remote Terminal.
This register typical contains an ASCII character that
is required for the E.164 numbering format.
NOTE: For more information on the use of this register,
please see Section 5.3.2.9.
2.4.3.13 Receive E3 TTB-2 Register (E3, ITU-T
G.832)
RXE3 TTB-2 REGISTER (ADDRESS = 0X1E)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
RxTTB-2
RO
RO
RO
RO
RO
RO
RO
RO
0
0
0
0
0
0
0
0
This Read-Only register contains the third (3rd) byte
within the 16 byte Trail Trace Buffer Message, that
has been received from the Remote Terminal. This
register typical contains an ASCII character that is re-
quired for the E.164 numbering format.
NOTE: For more information on the use of this register,
please see Section 5.3.2.9.
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