At least，I want to use ADAU1701 do three different EQ, a kind of EQ I know how to deal with and calls, but three different EQ should how to switch？
Do you want to change the EQ using the control port (I2C/SPI) or by using GPIO?
If you want to use the control port, then you'll need to calculate the filter coefficients and download them to the proper registers. There are several ways to do this. Here are some documents and videos that might help.
http://ez.analog.com/message/2799#2799 http://ez.analog.com/docs/DOC-1819 http://videos.analog.com/video/756712926001/SigmaStudio-C2-Capture-Window/ http://videos.analog.com/video/756712925001/SigmaStudio-C3-Parameters-Window/
If you want to use GPIO, please check out AN-951, which shows how to use GPIO to accomplish various tasks on SigmaDSP. The example with a pushbutton-controlled filter would fit your application.
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