Switches

Types

• Two-position
• Momentary
• Foot pedal
• Roller switches
• Mercury switch (binary tilt)
• Burgular alarm switches (optical, magnetic, ...)
• Multi-position switches ... need different approach than described here

Interfacing Switches to the Arduino Board

• Two-position switches should be positioned in a circuit so that their state can be distinguished by two distinct voltage levels (usually 0 or LOW and 5V or HIGH).

• Since only two values are possible, these can be read via digital input pins.

• The threshold for Arduino digital pin states is approximately 1.5V.
  

• Read pin value using digitalRead( pin ) function:

  int ledPin = 13; // LED connected to digital pin 13
  int inPin = 7;   // pushbutton connected to digital pin 7
  int val = 0;     // variable to store the read value
  
  void setup()
  {
    pinMode(ledPin, OUTPUT);    // sets the digital pin 13 as output
    pinMode(inPin, INPUT);      // sets the digital pin 7 as input
  }
  
  void loop()
  {
    val = digitalRead(inPin);     // read the input pin
    digitalWrite(ledPin, val);    // sets the LED to the button's value
  }