MT93L16 Mitel Networks Corporation, MT93L16 Datasheet - Page 8

• Manufacturer Part Number: MT93L16
• Description: CMOS Low-voltage Acoustic Echo CANceller
• Manufacturer: Mitel Networks Corporation

MT93L16
SSI Operation
The SSI PCM interface consists of data input pins
(Rin, Sin), data output pins (Sout, Rout), a variable
rate bit clock (BCLK), and two enable pins (ENA1,
ENA2) to provide strobes for data transfers. The
active high enable may be either 8 or 16 BCLK
cycles in duration. Automatic detection of the data
type (8 bit companded or 16 bit 2’s complement
linear) is accomplished internally. The data type
cannot change dynamically from one frame to the
next.
8
MD1
ST-BUS/GCI Mode 4 allows 16 bit 2’s complement linear data to be transferred using ST-BUS/GCI I/O timing. Note that PORT1 and
PORT2 need not necessarily both be in mode 4.
Enable Pins
Rin/Sout
0
0
1
1
PORT1
C4i
F0i (stbus)
F0i (GCI)
Rin
PORT1
Sout
Sin
PORT2
Rout
ENA1
Table 2 - ST-BUS & GCI Mode Select
0
1
0
1
Mode 1. 8 bit companded PCM I/O on
timeslot 0
Mode 2. 8 bit companded PCM I/O on
timeslot 2.
Mode 3. 8 bit companded PCM I/O on
timeslot 2. Includes D & C channel
bypass in timeslots 0 & 1.
Mode 4. 16 bit 2’s complement linear
PCM I/O on timeslots 0 & 1.
outputs = High impedance
inputs = don’t care
S 14 13 12 11 10 9 8
S 14 13 12 11 10 9 8
S 14 13 12 11 10 9 8
S 14 13 12 11 10 9 8
ST-BUS/GCI Mode
Figure 6 - ST-BUS and GCI 16-Bit 2’s complement linear PCM I/O (Mode 4)
Selection
start of frame (stbus & GCI)
EC
EC
7 6 5 4 3 2 1 0
7 6 5 4 3 2 1 0
7 6 5 4 3 2 1 0
7 6 5 4 3 2 1 0
MD2
Enable Pins
Sin/Rout
0
0
1
1
PORT2
ENA2
0
1
0
1
In SSI operation, the frame boundary is determined
by the rising edge of the ENA1 enable strobe (see
Figure 7). The other enable strobe (ENA2) is used
for parsing input/output data and it must pulse within
125 microseconds of the rising edge of ENA1.
In SSI operation, the enable strobes may be a mixed
combination of 8 or 16 BCLK cycles allowing the
flexibility to mix 2’s complement linear data on one
port (e.g., Rin/Sout) with companded data on the
other port (e.g., Sin/Rout).
PCM Law and Format Control (LAW, FORMAT)
The PCM companding/coding law used by the
MT93L16 is controlled through the LAW and
FORMAT pins. ITU-T G.711 companding curves for
coding
selected by the FORMAT pin. See Table 4.
-Law and A-Law are selected by the LAW pin. PCM
Enable Strobe Pin
ENA1
ENA2
Table 3 - SSI Enable Strobe Pins
ITU-T
G.711
Preliminary Information
Acoustic Side Echo Path (PORT 2)
Line Side Echo Path (PORT 1)
and
Designated PCM I/O Port
Sign-Magnitude
are