MT9074 Mitel Networks Corporation, MT9074 Datasheet - Page 34

• Manufacturer Part Number: MT9074
• Description: T1/E1/J1 Single Chip Transceiver
• Manufacturer: Mitel Networks Corporation

MT9074
34
will
synchronization is acquired.
When the CAS signalling interrupt is unmasked
(page 01H, address 1EH, SIGI=0), pin IRQ (pin 12 in
PLCC, 85 in MQFP) will become active when a
signalling nibble state change is detected in any of
the 30 receive channels.
In CCS mode the data transmit on channel 16 is
either sourced from channel 16 data on DSTi or from
the pin CSTi. Data received from channel 16 is
clocked out on CSTo (pin 5 in PLCC, pin 70 in
MQFP). By dividing down the extracted 2.048 MHz
clock.
Loopbacks
In order to meet PRI Layer 1 requirements and to
assist in circuit fault sectioning, the MT9074 has six
loopback functions. These are as follows:
a) Digital loopback (DSTi to DSTo at the framer/LIU
interface). Bit DLBK = 0 normal; DLBK = 1 activate.
b) Remote loopback (RTIP and RRING to TTIP and
TRING respectively at the DS1 side). Bit RLBK = 0
normal; RLBK = 1 activate.
c) ST-BUS loopback (DSTi to DSTo at the system
side). Bit SLBK = 0 normal; SLBK = 1 activate.
d) Payload loopback (RTIP and RRING to TTIP and
TRING respectively at the system side). Bit PLBK =
0 normal; PLBK = 1 activate. The payload loopback
is effectively a physical connection of DSTo to DSTi
System
System
System
become
DSTo
DSTo
DSTo
DSTi
DSTi
unfrozen
MT9074
MT9074
MT9074
when
Tx
Tx
Tx
Rx
DS1
DS1
DS1
multiframe
within the MT9074. Sbit information and the DL
originate at the point of loopback.
e) Metallic Loopback. MLBK = 0 normal; MLBK = 1
activate, will isolate the external signals RTIP and
RRING from the receiver and internally connect the
analog output TTIP and TRING to the receiver
analog input.
f) Local and remote time slot loopback. Remote time
slot loopback control bit RTSL = 0 normal; RTSL = 1
activate, will loop around transmit ST-BUS time slots
to the DSTo stream. Local time slot loopback bits
LTSL = 0 normal; LTSL = 1 activate, will loop around
receive PCM 30 time slots towards the remote PCM
30 end.
The digital, remote, ST-BUS, payload and metallic
loopbacks are located on page 1, address 15H -
Coding and Loopback Control Word. The remote and
local time slot loopbacks are controlled through
control bits 5 and 4 of the Per Time Slot Control
Words, pages 7H and 8H.
Performance Monitoring
Error Counters
In T1 mode, MT9074 has eight error counters, which
can be used for maintenance testing, an ongoing
measure of the quality of a DS1 link and to assist the
designer in meeting specifications such as TR62411
and T1.403. All counters can be preset or cleared by
writing to the appropriate locations.
System
System
System
DSTo
DSTo
DSTo
DSTi
DSTi
DSTi
MT9074
MT9074
MT9074
Advance Information
Tx
Rx
Tx
Rx
Tx
Rx
DS1
DS1
DS1