MSM7731-02 OKI [OKI electronic componets], MSM7731-02 Datasheet - Page 28

• Manufacturer Part Number: MSM7731-02
• Description: Dual Echo Canceler & Noise Canceler with Dual Codec for Hands-Free
• Manufacturer: OKI [OKI electronic componets]

B1, B0
1 Semiconductor
(0, 0): Initial mode
(1, 0): Dual echo canceler mode
(1, 1): Single echo canceler mode
(Other): Reserved bit (cannot be used)
Initial Mode
Figure 5 Initial Mode Flowchart
Modify default store memory
Operation mode selection
Approximately 200 ms after power-down reset is released, the initial mode is entered.
Only in this mode can the contents of the internal default value store memory be modified and CR0-B5
to CR0-B0, CR1-B7, CR1-B0, CR11-B1, CR11-B0, and CR12-B2 be set. In this mode, digital signal
output pins are at high impedance, digital communication input pins are internally processed as idle
pattern inputs, and neither the echo canceler nor the noise canceler operates. This mode is skipped when
the MCUSEL pin is a logic “1”. This mode is released by setting the modes shown below. Refer to the
flow chart of Figure 5.
The acoustic echo canceler, line echo canceler and other functions can be operated by control from the
control registers. Refer to Figure 6.
The initial setting for cancelable echo delay time is as follows:
The acoustic echo canceler and other functions can be operated by control from the control registers.
Control of the line echo canceler is unnecessary in this mode .Refer to Figure 7.
The initial setting for cancelable echo delay time is as follows:
Note: The MCUSEL pin is internally ORed with B1, and the ECSEL pin is internally ORed with B0. To
Start Normal Operation
Set control register
PDN/RST release
CR0-B1=1
PDN/RST
return to the initial mode after it has been released, activate power-down reset.
Acoustic delay time = 44 ms
Line delay time = 15 ms
Acoustic delay time = 59 ms
Wait for 200 ms
∙ Control registers are reset.
∙ Internal variables are reset.
YES
READY(CR11-B7) = 0
READY(CR11-B7) = 1
Power-down state
Automatic setting
Automatic setting
NO
Acoustic
Acoustic
CODEC
CODEC
Figure 7 Single Echo Canceler Mode
Figure 6 Dual Echo Canceler Mode
Canceler
Canceler
Acoustic
Acoustic
Echo
Echo
Canceler
Canceler
Noise
Noise
Slope
Slope
Filter
Filter
FEDL7731-02-04
MSM7731-02
Canceler
Echo
Line
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CODEC
CODEC
Line
Line