DIG ADC common configuration
| MEAS_NUM_LIMIT | Enable limit times of SAR ADC sample. |
| MAX_MEAS_NUM | Set maximum conversion number. |
| SAR1_INV | 1: data to DIG ADC1 CTRL is inverted, otherwise not. |
| SAR2_INV | 1: data to DIG ADC2 CTRL is inverted, otherwise not. |
| TIMER_SEL | 1: select saradc timer 0: i2s_ws trigger |
| TIMER_TARGET | Set SAR ADC timer target. |
| TIMER_EN | Enable SAR ADC timer trigger. |