1.输入1kHz的正玄波，输出变成了2kHz。并且有其他频段的干扰。
2.不接任何输入的时候，有大约25db的噪声信号，频率大概在45Hz-100Hz。
I2S模式，MCLK=12.288M fs=48k BCLK=1.536M，16位
寄存器配置如下：
I2CWRITE(I2C_ADC31, 0, 0X0);
I2CWRITE(I2C_ADC31, 1, 0X01);
I2CWRITE(I2C_ADC31, 4, 0X03);//use PLL
I2CWRITE(I2C_ADC31, 5, 0X91);//P R
I2CWRITE(I2C_ADC31, 6, 0X01);//J
I2CWRITE(I2C_ADC31, 7, 0X00);//D MSB
I2CWRITE(I2C_ADC31, 8, 0X00);//D LSB
I2CWRITE(I2C_ADC31, 18, 0X81);//NADC
I2CWRITE(I2C_ADC31, 19, 0X82);//MADC
I2CWRITE(I2C_ADC31, 20, 0X80);//AOSRS
I2CWRITE(I2C_ADC31, 27, 0X00);
I2CWRITE(I2C_ADC31, 61, 0X01);
// Set register ------------------------->page 1
I2CWRITE(I2C_ADC31, 0, 0X01);
I2CWRITE(I2C_ADC31, 51, 0X0);
I2CWRITE(I2C_ADC31, 59, 0X0);
I2CWRITE(I2C_ADC31, 60, 0X0);
I2CWRITE(I2C_ADC31, 52, 0XFC);
I2CWRITE(I2C_ADC31, 55, 0XFC);
// Set register ------------------------->page 0
I2CWRITE(I2C_ADC31, 0, 0X0);
I2CWRITE(I2C_ADC31, 81, 0XC2);
I2CWRITE(I2C_ADC31, 82, 0X0);
I2CWRITE(I2C_ADC31, 83, 0X0);
I2CWRITE(I2C_ADC31, 84, 0X0);
原理图如下：
