//pin connected to sensor const int analogPin = A0; void setup() { Serial.begin(9600); //internal reference 1.1V //we are measuring very low signal and have only 10bit ADC analogReference(INTERNAL); } void loop() { unsigned int sensorRead = analogRead(analogPin); //map ADC value to volatage drop on transistor/diode int voltageDrop = map(sensorRead, 0, 1023, 0, 1100); Serial.print("ADC:"); Serial.print(sensorRead); Serial.print(" voltageDrop:"); Serial.print(voltageDrop); Serial.println(" mV"); Serial.println("-----------------------------"); delay(300); }