void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  
}
float v;
float k;
void loop() {
  // put your main code here, to run repeatedly:
  ADC = analogRead(A0);
  v = ADC * 5.0/1024;
  k = (ADC-2.5)/2.0;
  Serial.print("ADC: ");Serial.print(ADC);
  Serial.print("\tV: ");Serial.print(v);
  Serial.print("\tK: ");Serial.print(k);
  Serial.println();
  delay(500);
}