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
07 7
6
5
4
3
2
1
0
Symbol
EXEC
CON/DIS
LBSEL
D22
D21
D20
D11
D10
Description
Remote Loopback. The bits in this register are used to send a DS1 remote loop-
back request in the M13 mode, or a DS3/DS1 remote loopback request in the C-bit
parity mode.
Bit 7 (EXEC) executes the command. In the M13 mode, a one in this bit ascertains
the remote loopback request and a zero removes a remote loopback request. In
the C-bit parity mode, a one written to this bit sends a remote loopback connect or
disconnect command and once the command is transmitted, bit 7 (EXEC) is auto-
matically reset to zero (see below Remote Loopback in C-bit parity mode).
Bit 6 (CON/DIS) sends the command to connect or disconnect the loopback
selected. This bit is not used in the M13 mode and effective only in the C-bit parity
mode.
Bit 5 (LBSEL) selects either the M13 mode (LBSEL=0) or C-bit parity mode
(LBSEL=1). The C or stuff bit inversion mechanism selected by the four 1LBV bits
in location 20H, is used for remote loopback in the M13 mode. In the C-Parity
mode, the MT90737 automatically translates date written in this register to the
FEAC (C3) code word which is used to send DS1 and DS3 remote loopback
requests.
Bits 4-0 select the DS1 channel to be looped back. Bits 4 (D22), 3 (D21), and 2
(D20) select the DS2 frame (1-7). Bits 1 (D11) and 0 (D10) select one of four DS1
channels.
Remote Loopback in C-bit parity mode:
In the C-bit parity mode, the MT90737 translates the channel to be looped back as
written in bits 4-0 into the FEAC code word. To send a loopback request, the
MT90737 sends ten repetitions of the FEAC line activator code sequence (0
000111 0 11111111) followed immediately by ten repetitions of the loopback code
word (0 xxxxxx 0 11111111). At the end of this sequence (20 code words or 320
DS3 frames), completion is indicated by bit 7 (EXEC) resetting to zero. To deacti-
vate a loopback in the C-bit parity mode, the MT90737 sends ten repetitions of the
deactivate code followed immediately by ten repetitions of the channel selected.
Only one loopback request can be sent at a time. The codes for sending and deac-
tivating an M13, or a C-bit parity remote loopback request are shown below:
Bits 7
6
5
4
3
2
1
0
Channel
EXEC CON/DIS LBSEL D22 D21 D20 D11 D10
All
1
X
X
0
0
0
0
0
Channel 1
1
X
X
0
0
1
0
0
Channel 2
1
X
X
0
0
1
0
1
----------- ------- --------- ------ ----- ----- ----- ------ ------
Channel 28
1
X
X
1
1
1
1
1
DS3
1
X
1
0
0
0
1
0
5-79
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