MT9196 Mitel Semiconductor, MT9196 Datasheet - Page 15

• Manufacturer Part Number: MT9196
• Description: Integrated Digital Phone Circuit (IDPC)
• Manufacturer: Mitel Semiconductor

Preliminary Information
For synchronous operation data is sampled, from
Din, on the falling edge of the bit clock during the
time slot defined by the STB input. Data is made
available, on Dout, on the rising edge of the bit clock
during the time slot defined by the STB input. Dout is
tri-stated at all times when STB is not true. If STB is
valid but no transmit path has been selected (via the
Transmit Path Control Register) then quiet code will
be transmitted on Dout during the valid strobe
period.
circuit for synchronous operation.
For asynchronous operation Dout and Din are as
defined for synchronous operation except that data
is transferred according to the itnernally generated
bit clock. Due to resynchronization circuitry activity,
the output jitter on Dout is nominally larger but will
not affect operation since the bit cell period at 128
kb/s and 256 kb/s is relatively large. There is a one
frame delay through the FDI circuit for asynchronous
operation. Refer to the specifications of Figures 13
and 14 for both synchronous and asynchronous SSI
timing.
Path Selection
Transmit and receive audio paths are independently
programmed through their respective Path Control
Registers at addresses 12h and 13h. Individual
audio path circuit blocks are powered up only as they
are required to satisfy the programmed values in the
path control registers. More detail is provided in the
Power-up/down Reset section.
Transmit
Transmit audio path configuration (Path Control
Register, address 12h) is simply a matter of
assigning one of the three analog signal inputs, or
the digital tone generator, to the required transmit B-
Channel. Intermediate functions such as the transmit
Asynch/
Synch
1
1
0
0
0
0
There is no frame delay through the FDI
CSL1 CSL0
0
0
0
0
1
1
0
1
0
1
0
1
Table 3
Rate (kHz)
Bit Clock
1536
2048
4096
128
256
512
mandatory
mandatory
CLOCKin
(kHz)
4096
4096
1536
2048
4096
512
filter, encoder and transmit gain are automatically
powered up and assigned as required. If transmit
tones is selected then the digital tone generator must
be programmed and enabled properly as described
in the Digital Tone Generator section. Note that
transmit tones may be enabled independently of the
receive path.
For ST-BUS mode the configuration of bits 0 to 3, at
address 12h, defines both the source of transmit
audio
configuration of this register permits selection of only
one transmit B-Channel at a time. For SSI mode only
the selections where bit 3 = 0 are allowed. This is
because the B-Channel timeslot is defined by the
input strobe at STB. If a selection where bit 3 = 1 is
made it will be treated the same as the condition
where B3 - B0 = all zero's.
All reserved configurations should not be used.
Receive
The receive path assignment (Receive Path Control
Register, address 13h) is different from the transmit
path assignment. In this case a particular analog
output port is assigned a source for its audio signal.
The receive filter audio path and the Auxiliary In
analog
configuration allows flexibility in assignment. Two
examples; the receive filter path can be assigned to
the handset receiver, for a standard handset
conversation, while permitting the loudspeaker to
announce a message originating from the Auxiliary
In port. Or perhaps the receive filter is assigned to
both the loudspeaker and the Auxiliary Out port. This
would allow a voice recorder or Facsimile machine,
connected to the AUXout port to be monitored over
the loudspeaker.
The receive filter path itself has two possible signal
sources, PCM from the Din port or synthesized
tones, from the digital tone generator. In both cases
receive digital gain is assigned automatically. The
Receive Path Control Register combines all of these
choices into simple output port assignments.
In ST-BUS mode receive PCM from the Din port
must be selected from either the B1 or the B2
channel. Control Bit B2/B1 in Control Register 1
(address 0Eh) is used to define the active receive B-
Channel. In SSI mode the active PCM channel is
automatically defined by the STB input signal.
and
port
the
are
B-Channel
the
available
destination.
choices.
MT9196
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