Now works very good
MIC with amp connect to A1 with 3,3V power
int sensorPin = A1;
int sensorValue = 0;
void setup() {
analogReadResolution(8);
analogWriteResolution(16);
Serial.begin(9600);
ADC->REFCTRL.bit.REFSEL = ADC_REFCTRL_REFSEL_INTVCC0_Val;
ADC->AVGCTRL.reg = 0x00; //Single conversion no averaging
GCLK->CLKCTRL.reg = 0x431E; //enable GGCLK for ADC, CLKGEN3 = 8 MHz oscillator
ADC->CTRLB.reg = 0x000; // Prescale 4, 12 bit resolution, single conversion
}
void loop() {
//sensorValue= map (analogRead(A5),0,4096,0,1023);
sensorValue= analogRead(sensorPin)<<1;
// Serial.println(analogRead(A5));
analogWrite(A0, sensorValue);
}