CapTouch

float offset;
float distance;
float distance_raw;
float filter_coef = 0.025;
float measureToDistance = 1;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  offset=0;
  /*
  for (int i = 0; i < 1000; i++) {
    offset += measure();
  }
  offset /= 1000;
  */
}

void loop() {
  // put your main code here, to run repeatedly:
  distance_raw = ((float)capMeasure() - offset) * measureToDistance;
  distance = distance * (1 - filter_coef) + distance_raw * filter_coef;
  Serial.print(distance_raw);
  Serial.print(',');
  Serial.print(distance);
  Serial.println();
  delay(10);
}

unsigned int capMeasure() {
  //charge share capacitance measure on A1 pin. A0 is used to charge S/H cap
  pinMode(A1, OUTPUT);
  pinMode (A0, INPUT_PULLUP);
  analogRead(A0);
  pinMode(A1, INPUT);
  unsigned long value = analogRead(A1);
  pinMode(A1, OUTPUT);
  return value;
}