msm7731-01 Oki Semiconductor, msm7731-01 Datasheet - Page 29

• Manufacturer Part Number: msm7731-01
• Description: Multifunction Pcm Codec Voice Signal Processor
• Manufacturer: Oki Semiconductor

¡ Semiconductor
B1, B0 ... Operating mode selection
Figure 5 Initial Mode Flowchart
Initial mode
(0, 0):
(1, 0):
(1, 1):
(Other): Reserved bit (cannot be used)
Modify default store memory
Power-down reset release
Start normal operation
Set control register
Power-down reset
CR0–B1=1
Initial mode
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, CR11-B1 and CR11-B0 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 "1". This mode is released by setting the modes shown below.
Refer to the flowchart of Figure 5.
Dual echo canceler mode
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:
Single echo canceler mode
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.
Note: The MCUSEL pin is internally ORed with B1, and the ECSEL pin is
Acoustic delay time (Tacoud) = 44 ms
Line delay time (Tlined) = 15 ms
Power-down state
Wait for 200 ms
YES
• Control registers are reset
• Internal variables are reset
internally ORed with B0. To return to the initial mode after it has been
released, activate power-down reset.
NO
Note: During the initial mode, the READY bit
Acoustic
CODEC
Acoustic
CODEC
Figure 7 Single Echo Canceler Mode
Figure 6 Dual Echo Canceler Mode
(CR11-B7) is "1", at all other times it is "0".
Acoustic
Echo
Canceler
Acoustic
Echo
Canceler
Noise
Canceler
Noise
Canceler
Slope
Filter
Slope
Filter
Line
Echo
Canceler
MSM7731-01
Line
CODEC
Line
CODEC
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