XRT72L13 Datasheet, PDF (364/370 Pages) Exar Corporation – M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC

XRT72L13
M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC
REV. P1.0.6
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PRELIMINARY
This section discusses the various configuration op-
tions and features that are available whenever the
XRT72L13 has been configured to operate in the
“DS2 Pass-Thru” Mode.
Configuring M12 MUX # 1 into the “DS2 Pass Th-
ru” Mode
The user can configure M12 MUX # 1 to operate in
the “DS2 Pass-Thru” Mode by setting Bit 4 (M12
G.747) to “0” and Bit 5 (M12 Bypass) to “1” within the
“M12 DS2 # 1 Configuration” Register, as illustrated
below.
M12 DS2 # 1 CONFIGURATION REGISTER (ADDRESS = 0X1A)
BIT 7
Reserved
7
R/W
X
BIT 6
Reserved
6
R/W
X
BIT 5
M12
Bypass
R/W
1
BIT 4
M12
G.747
R/W
0
BIT 3
M12
G.747 Res
R/W
X
BIT 2
M12 FERF
R/W
X
BIT 1
BIT 0
M12LBCode[1:0]
R/W
R/W
X
X
Once the user implements this configuration setting,
then M12 MUX # 1 will be configured to operate in the
“DS2 Pass-Thru” mode. When M12 MUX # 1 is oper-
ating in the “DS2 Pass-Thru” Mode, then it will be
configured to accept a DS2 signal, via the
“TxDS1Data_3” input pin. In this case, the M12 MUX
will perform no processing on this DS2 signal, and will
simply route it to the M23 MUX block.
5.2.1.2 Operation of the M23 MUX Block
As mentioned earlier, the XRT72L13 consists of sev-
en M12 MUX blocks and a single M23 MUX block.
The purpose of the M23 MUX block is to accept sev-
en signals (which can either be DS2 signals or “ITU-T
G.747” signals, from each of the seven M12 MUX
blocks); and to multiplex these signals into a DS3 da-
ta stream.
5.2.2 Channelized Operation, while the
XRT72L13 is operating in the “C-Bit Parity” Fram-
ing Format.
5.3 CHANNELIZED OPERATION IN THE RECEIVE
DIRECTION
5.3.1 Channelized Operation, while the
XRT72L13 is operating in the “M13” Framing For-
mat.
5.3.1.1 Operation of the M23 DEMUX Block
The purpose of the M23 DEMUX Block is to accept a
DS3 data stream, and to de-multiplex this data into
seven signals. These signals can either be DS2 sig-
nals or “ITU-T G.747” signals. The output of the M23
DEMUX block will then be routed to each of the vari-
ous M12 DEMUX Blocks.
5.3.1.2 Operation of the M12 DEMUX Blocks
The XRT72L13 consists of seven M12 DEMUX
blocks. The purpose of each of these blocks are to:
• Accept a DS2 signal (from the M23 DEMUX) and to
de-multiplex these signals into four DS1 signals.
• Accepts a “G.747” signal (from the M23 DEMUX)
and to de-multiplex these signals into three E1 sig-
nals.
• Accept a DS2 signal from the M23 DEMUX, and (if
configured) route this signal directly to the output
pins.
A more detailed description of the Operation of the
M12 DEMUX is presented below.
5.3.1.2.1 DS1 Operation of the M12 DEMUX
As mentioned earlier, the XRT72L13 consists of sev-
en (7) M12 MUX blocks. Each of these M12 MUX
blocks can be independently configured to operate in
either DS1, the E1 (or ITU-T G.747) or the “DS2
Pass-Thru” Mode.
5.3.1.2.1.1 Configuring the M12 DEMUX # 1
into the DS1 Mode
The user can configure M12 DEMUX # 1 to operate in
the “DS1” Mode by setting Bits 4 (M12 G.747) and 5
(M12 By-Pass) to “0”, within the “M12 DS2 # 1 Con-
figuration” Register, as illustrated below.
M12 DS2 # 1 CONFIGURATION REGISTER (ADDRESS = 0X1A)
BIT 7
Reserved
7
R/W
X
BIT 6
Reserved
6
R/W
X
BIT 5
M12
Bypass
R/W
0
BIT 4
M12
G.747
R/W
0
BIT 3
M12
G.747 Res
R/W
X
BIT 2
M12 FERF
R/W
X
BIT 1
BIT 0
M12LBCode[1:0]
R/W
R/W
X
X
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