Capacitive Sensor

capSense_example.ino

#include <CapacitiveSensor.h>

/*
   CapitiveSense Library Demo Sketch
   Paul Badger 2008
   modified by Eric Forman 2017

   Install library from Arduino IDE: Go to Sketch / Include Library / Manage Libraries, then search for "capacitiveSensor"
   and select library by Paul Badger, Paul Stoffregen, select latest version, click Install.

   Use a high value resistor (e.g. 10M, or 10 mega-ohm) between send pin and receive pin
   Resistor effects sensitivity: experiment with values, 50K - 50M. Larger resistor values yield larger sensor values

   Receive pin is the sensor pin - try different amounts of foil/metal on this pin
   Best results are obtained if sensor foil and wire is covered with an insulator such as paper or plastic sheet

   Determine the raw values of your sensor first, then adjust map() parameters
   Optional: use a smoothing function after mapping
   
   This code sends both the raw value and the mapped value to the serial port for debugging, but likely 
   you will only want to send one or the other
*/


// pin 4 is the send pin: 10 megaohm resistor between pins 4 and 2
// pin 2 is the receive pin: connect sensor (something metal)
CapacitiveSensor   cs_4_2 = CapacitiveSensor(4, 2);       

int ledPin = 9;    // LED connected to digital pin 9


void setup() {
  Serial.begin(9600);
  pinMode(ledPin, OUTPUT);
}


void loop() {
  // parameter is # of samples, i.e. sensor resoultion. Default 30.
  // increase for higher res, but slower performance.
  long sensorVal =  cs_4_2.capacitiveSensor(50);    

  // debug raw sensor output value
  Serial.print(sensorVal);

  // map sensor value to LED PWM brightness 0-255 range
  // (change "5, 5500" to the minimum, maximum raw values of your sensor)
  sensorVal = map(sensorVal,  5, 5500,  0, 255);

  // make sure value is between 0-255
  sensorVal = constrain(sensorVal, 0, 255);

  Serial.print("\t");                    // print "tab" character
  Serial.println(sensorVal);             // print re-mapped value

  // output LED with relative brightness:
  analogWrite(ledPin, sensorVal);

  delay(10);                             // arbitrary delay to limit data to serial port
}