CM6571 Datasheet, PDF (44/63 Pages) C-Media Electronics – USB 2.0 full speed-compliant

CM6571
USB Audio Sound Chip
9.3 Recommended control methods for DSP core
There are three recommended control scenarios for different customer considerations. These are as follows:
9.3.1 scenario I
Mode_Sel pins control for no custom tuning or just programming parameters with the best power saving
In typical cases, when all default HW settings and DSP algorithm ROM codes could satisfy your needs, or you just need
to change some ROM code parameters or set HW registers through I2C interface, we suggest you use Mode_Sel 0/1 pins
to simply control chip operation mode for better power saving. In this way, the Power Down mode will go into power
level 0 and consume almost no power for Phone Standby/Sleep/Deep Sleep or Power-Off status. When phone is active
during a call, switch to ENC mode by baseband’s active signal pin or a GPIO pin (drive high) to Mode_Sel0 pin. Pull it low
back to Power Down when ending a call to Standby status. Another GPIO pin could drive Mode_Sel1 pin high (while
Mode_Sel 0 is high at the same time) to enter By-Pass mode when you choose to turn off ENC function or when the
design does not use CM6571’s AEC or NR functions in speakerphone and recorder applications. The phone status should
match the following operation modes:
Phone Status
Operation Mode
Mode_Sel0/1
Control
Power-Off
Power Down (No
power supply)
Mode_Sel 0=0
Mode_Sel 1=0
Stand-By/Sleep/De
ep Sleep
Active (Effect On)
Active
Power Down (ENC ON, or AEC or NR
by I2C command)
Mode_Sel 0=0
Mode_Sel 0=1
Mode_Sel 1=0
Mode_Sel 1=0
Active (Effect Off)
By-Pass
Mode_Sel 0=1
Mode_Sel 1=1
In this scenario, note that the baseband needs to program the parameters or HW registers through I2C every time
before entering into Phone Active/Calling status with ENC chip working (very short time~0.12ms).
Revised: Nov. 2012
Page 44 / 63
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