最近笔者在做声卡相关设备，既要满足优质的人声输入控制，也要有良好的输出调制，对比多家调试了多款Codec，最终选用了WM8988。因为配置比较复杂，这里笔者把一些关键部分提供给大家参考参考
先来看看WM8988内部结构框图，开发者可通过它和相关的几十个寄存器衔接起来做出适合的配置
下面贴下，初始化代码
#define WM8988_DEV0_ADDR (0x1a) // 7~1 bit addr
#define WM8988_DEV1_ADDR (0x1b) // 7~1 bit addr
#define WM8988_LINVOL 0x00
#define WM8988_RINVOL 0x01
#define WM8988_LOUT1V 0x02
#define WM8988_ROUT1V 0x03
#define WM8988_ADCDAC 0x05
#define WM8988_IFACE 0x07
#define WM8988_SRATE 0x08
#define WM8988_LDACVOL 0x0a
#define WM8988_RDACVOL 0x0b
#define WM8988_BASS 0x0c
#define WM8988_TREBLE 0x0d
#define WM8988_RESET 0x0f
#define WM8988_3D 0x10
#define WM8988_ALC1 0x11
#define WM8988_ALC2 0x12
#define WM8988_ALC3 0x13
#define WM8988_NGATE 0x14
#define WM8988_LADCVOL 0x15
#define WM8988_RADCVOL 0x16
#define WM8988_ADCTL1 0x17
#define WM8988_ADCTL2 0x18
#define WM8988_PWR1 0x19
#define WM8988_PWR2 0x1a
#define WM8988_ADCTL3 0x1b
#define WM8988_ADCIN 0x1f //可配置输入MIX
#define WM8988_LADCIN 0x20 //MIC 相关配置
#define WM8988_RADCIN 0x21 //MIC 相关配置
#define WM8988_LOUTM1 0x22
#define WM8988_LOUTM2 0x23
#define WM8988_ROUTM1 0x24
#define WM8988_ROUTM2 0x25
#define WM8988_LOUT2V 0x28
#define WM8988_ROUT2V 0x29
#define WM8988_LPPB 0x43
#define WM8988_NUM_REG 0x44
#define wm8988_DVE0_write_reg(reg,data) xBSP_Codec_Write(WM8988_DEV0_ADDR, (uint8_t)((reg<<1)|(data>>8)), (uint8_t)(data&0xff))
static void xSYS_WM8988_Config(void)
{
//Data Reset
wm8988_DVE0_write_reg(WM8988_RESET,0x00);
//19h 1ah Power Management
wm8988_DVE0_write_reg(WM8988_PWR1,0x01);
wm8988_DVE0_write_reg(WM8988_PWR2,0x00); //inactive
//ADC LR Signal path: LRINSEL LRMICBOOST
wm8988_DVE0_write_reg(WM8988_LADCIN,0x40); //0x00 //0x40 选通 输入2
wm8988_DVE0_write_reg(WM8988_RADCIN,0x40); //0x00
//Left out Mix 1/2 //这里只走DAC转换的数据
wm8988_DVE0_write_reg(WM8988_LOUTM1,0x122); //0x1a0 DAC 和 MIXSEL 都走这里
wm8988_DVE0_write_reg(WM8988_LOUTM2,0x70); //70
//Right out Mix 1/2
wm8988_DVE0_write_reg(WM8988_ROUTM1,0x70); //70
wm8988_DVE0_write_reg(WM8988_ROUTM2,0x122);
//19h 1ah Power Management
// wm8988_DVE0_write_reg(WM8988_PWR1,0x1fc); //
// wm8988_DVE0_write_reg(WM8988_PWR2,0x1f8); //active·
wm8988_DVE0_write_reg(WM8988_PWR1,0x17c); //
wm8988_DVE0_write_reg(WM8988_PWR2,0x1f0); //active 三路输出
//ADC and DAC Contrl
wm8988_DVE0_write_reg(WM8988_ADCDAC,0x08); //08 Mute
//LR Input volume
wm8988_DVE0_write_reg(WM8988_LINVOL,0x117); //197
wm8988_DVE0_write_reg(WM8988_RINVOL,0x117);
//LR Out1 volume
wm8988_DVE0_write_reg(WM8988_LOUT1V,0x100); //0dB:179
wm8988_DVE0_write_reg(WM8988_ROUT1V,0x100);
//LR OUT2 VOL
wm8988_DVE0_write_reg(WM8988_LOUT2V,0x179); //0dB
wm8988_DVE0_write_reg(WM8988_ROUT2V,0x100); //这个不输出
//LR ADC Digital Vol
wm8988_DVE0_write_reg(WM8988_LADCVOL,0x1c3); //MIC 默认 0 dB
wm8988_DVE0_write_reg(WM8988_RADCVOL,0x1c3);
//LR DAC Volume
wm8988_DVE0_write_reg(WM8988_LDACVOL,0x1ff); //0dB //0x1ff
wm8988_DVE0_write_reg(WM8988_RDACVOL,0x1ff); //
//Audio Interface Format
wm8988_DVE0_write_reg(WM8988_IFACE,0x0a); //24bit I2s
//Sample Rate
wm8988_DVE0_write_reg(WM8988_SRATE,0x20);
//Bass/Treble Control
wm8988_DVE0_write_reg(WM8988_BASS,0x0f);
wm8988_DVE0_write_reg(WM8988_TREBLE,0x0f);
//3D enhance
wm8988_DVE0_write_reg(WM8988_3D,0x00);
//ALG Ctrl 1/2/3
wm8988_DVE0_write_reg(WM8988_ALC1,0x7B);
wm8988_DVE0_write_reg(WM8988_ALC2,0x00);
wm8988_DVE0_write_reg(WM8988_ALC3,0x32);
//Noise Gate
wm8988_DVE0_write_reg(WM8988_NGATE,0x00);
//Additional ctrl 1/2/3
wm8988_DVE0_write_reg(WM8988_ADCTL1,0x00);
wm8988_DVE0_write_reg(WM8988_ADCTL2,0x00);
wm8988_DVE0_write_reg(WM8988_ADCTL3,0x00);
//Low Power Playback
wm8988_DVE0_write_reg(WM8988_LPPB,0x00);
//ADC input mode
wm8988_DVE0_write_reg(WM8988_ADCIN,0x100); //0x00
//ADC and DAC Contrl
wm8988_DVE0_write_reg(WM8988_ADCDAC,0x00);
}
如代码和上图寄存器图所示，可知道输入输出音量相关的寄存器就有十个左右，工程师需根据实际情况去做调节（模拟，数字均可调节）；另外还有混合相关的寄存器值得注意。
电路设计可参考如下：
