Mic Gain Debug

EQ Tool

Sifli_EQ The EQ tool can adjust the digital microphone gain by modifying the variable g_adc_volume in the file drv_audprc.c. The default value of this variable is 0, and reducing it decreases the microphone gain. Most echo cancellation algorithms require microphone sampling values to remain between 3k and 5k. The microphone sampling values can be captured using the audio dump tool. Currently, the platform software for the microphone is set to 16-bit, with a saturation range of -32768 to +32767. Sometimes, when the microphone gain is lowered, it may saturate at lower values, affecting echo cancellation performance. At this point, the g_adc_volume can be set to 0 to adjust the rough volumeThe code is located in bf0_hal_audcodec.c (56x/58x platform) or bf0_hal_audcodec_m.c (52x/57x platform)Here, the rough vol is set to 0xc. To address this, reduce the value corresponding to ADC_CH0_CFG_ROUGH_VOL by changing it from 0xc to 0xa. By appropriately lowering the rough vol, this digital gain value can be reduced to improve the issue of excessively low saturation. The step size for the value of ROUGH_VOL is 6 dB, with the corresponding settings as follows:

0   ----- -60db  
1   ----- -54db  
    ...  
    ...  
0xa -----   0db  
0xb -----   6db  
    ...  
0xf -----  30db  

FINE_VOL value is 0 ~ 0xc，corresponding 0~6db, step is 0.5db

//56x/58x code
hacodec->Instance_lp->ADC_CH0_CFG = (1   << AUDCODEC_LP_ADC_CH0_CFG_ENABLE_Pos) |
                                            (0   << AUDCODEC_LP_ADC_CH0_CFG_HPF_BYPASS_Pos) |
                                            (0x7 << AUDCODEC_LP_ADC_CH0_CFG_HPF_COEF_Pos) |
                                            (0   << AUDCODEC_LP_ADC_CH0_CFG_STB_INV_Pos) |
                                            (0   << AUDCODEC_LP_ADC_CH0_CFG_DMA_EN_Pos) |
                                            (0xc << AUDCODEC_LP_ADC_CH0_CFG_ROUGH_VOL_Pos) |
                                            (0   << AUDCODEC_LP_ADC_CH0_CFG_FINE_VOL_Pos) |
                                            (1   << AUDCODEC_LP_ADC_CH0_CFG_DATA_FORMAT_Pos);

//52x/57x
        hacodec->Instance->ADC_CH0_CFG = (1   << AUDCODEC_ADC_CH0_CFG_ENABLE_Pos) |
                                         (0   << AUDCODEC_ADC_CH0_CFG_HPF_BYPASS_Pos) |
                                         (0x7 << AUDCODEC_ADC_CH0_CFG_HPF_COEF_Pos) |
                                         (0   << AUDCODEC_ADC_CH0_CFG_STB_INV_Pos) |
                                         (0   << AUDCODEC_ADC_CH0_CFG_DMA_EN_Pos) |
                                         (0xc << AUDCODEC_ADC_CH0_CFG_ROUGH_VOL_Pos) |
                                         (0   << AUDCODEC_ADC_CH0_CFG_FINE_VOL_Pos) |
                                         (1   << AUDCODEC_ADC_CH0_CFG_DATA_FORMAT_Pos);