MT90737 Просмотр технического описания (PDF) - Mitel Networks
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MT90737 Datasheet PDF : 40 Pages
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Preliminary Information
CMOS MT90737
Addr Bit
02 7
6
5
4
3
2
1
0
03 7
6-0
Symbol
Description
IDLB
IDLA
DS1 Idle Code Selection. Three types of DS1 idle codes are provided according
to the table given below. A selected idle code is common to all DS1 channels
selected. One or more transmitted DS1 channels can be selected by writing a one
in IDLn register locations 10, 11, 12, or 13 Hex, provided register 1E Hex has not
selected these DS1 channels for loopback.
IDLB
0
1
X
IDLA
0
0
1
DS1 Idle Code Selected
Quasi-Random Signal (220 - 1 QRS) including zero suppression.
Framed Extended Super Frame (ESF) signal format which consists
of a Framing Pattern Sequence of 001011 pattern, CRC-6 pattern,
and ones in the 64kbit/s channels 1 through 24.
Unframed all ones signal (AIS).
TEST1
3LBK
LPTIME
INVCK
1INV
MODE
CBIT1
DS2OOFn
(n=7-1)
Reserved for Testing Purposes. A zero must be written into this bit position for
normal operation.
DS3 Line Loopback. A one disables the DS3 receive input and causes the DS3
transmit output to be looped back as receive data. Transmit data is provided at the
output (DS3DT). A zero allows MT90737 to be in normal operation.
Receive Loop Timing. A one disables the transmit clock input (XCK), and causes
the DS3 receive clock to become the DS3 transmit clock. If the DS3 receive clock
fails in this mode, the MT90737 switches over to the transmit clock, and the demul-
tiplexer becomes inoperative, however, the multiplexer and microprocessor inter-
face continue to function.
Invert DS1 Transmit Clocks. A one causes all transmit DS1 clock inputs (CTn) to
be inverted. This is provided for back-to-back M13 operation.
Invert DS1 Transmit Data. A one causes the transmit data inputs for all DS1
channels (DTn) to be inverted.
Operating Mode. A one enables the MT90737 to operate in the M13 mode as
specified in Bellcore TR-TSY-000009, and the ANSI T1.107-1988 standard. A zero
enables the MT90737 to operate in the C-bit parity mode as specified in the ANSI
T1.107a-1990, supplement to ANSI T1.107-1988.
C-bit Number 1. This bit is updated each frame with the state of the received C1.
The C1 bit is used to identify the DS3 application according to the table given
below.
C1 Value
Application
Random
M13 format
All 1s
C-bit parity format
In addition, the number of C1 bits equal to zero is counted by the C1 Bit Zero
Counter (C1BZn) in 22 Hex.
DS2 Out of Frame Alarm Indication. A one in bits 6-0 corresponds to an out of
frame alarm for the respective DS2 channel (7-1). A DS2 OOF occurs when two
out of four consecutive DS2 framing bits are in error. A DS2 OOF for a DS2 chan-
nel causes AIS to be inserted into its four DS1 channels. Recovery is based on
searching for the correct DS2 framing pattern (0101...). Once the framing pattern is
found, one more frame is used to acquire alignment. Recovery takes approxi-
mately 6.8 milliseconds, worst case average.
5-77
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