Understanding of Capacitive Touch Sensor

A capacitive sensor is a type of sensor that detects and measures changes in capacitance, typically caused by the proximity, presence, or movement of objects. It works by generating an electric field and measuring the effect of an object.

01. Using Capacitive Sensor Library

The CapacitiveSensor library in Arduino provides a simple way to implement capacitive touch or proximity sensors.

How It Works

1. Charging and Discharging Principle:

   • Capacitors store and release electrical charge.
   • The library sets one pin for charging and another pin for sensing.
   • The sensor measures the change in capacitance at different points on its surface.

2. RC Circuit

   • The resistance (R) and capacitance (C) affect the time it takes to charge or discharge the circuit.
   • The library measures the time for the sensing pin to reach a HIGH (logic 1) state, which increases with larger capacitance.

   time = R⋅C

   1. Measuring Charge Time:

      • The library repeatedly measures the charge time of the sensing pin.
      • An increase in charge time indicates higher capacitance, suggesting the presence of a nearby object.

      

capacitiveSensor(sampleCount) Function:

• This measures capacitance by sampling the charge time of the sensing pin sampleCount times.
• It returns the total time, where higher values indicate higher capacitance (e.g., an object closer to the sensor).

#include <CapacitiveSensor.h>

CapacitiveSensor capSensor1 = CapacitiveSensor(4,2);
CapacitiveSensor capSensor2 = CapacitiveSensor(4,3);

void setup() {
  Serial.begin(9600);
  // put your setup code here, to run once:
  //pin 4 transmitter
  //pin 2 reciever
  //pin 3 reciever
}

void loop() {
  // put your main code here, to run repeatedly:

//store the value reported by the sensor in a variable
long sensorValue1 = capSensor1.capacitiveSensor(30);
long sensorValue2 = capSensor2.capacitiveSensor(30);

Serial.print(sensorValue1);
Serial.print(", ");
Serial.println(sensorValue2);
delay(100);

}