Arduino Pull-up Pull-down Resistor

  • What is pull-up and pull-down resistor?
  • Pull-up Resistor vs Pull-down Resistor?
  • Why do we need to use it with Arduino?
  • When do we need to use it?
  • How to use pull-up and pull-down resistor with Arduino?

What is pull-up and pull-down resistor

A pull-up resistor or a pull-down resistor is used with a digital input pin of Arduino, as well as other micro-controller, to prevent the floating input issue

The terms pull-up and pull-down imply how the resistor is wired (will be presented in the next part).

Pull-up Resistor vs Pull-down Resistor

The pull-up resistor and pull-down resistor solve the floating input problem. Let's take the button with a pull-up or pull-down resistor for example. The other digital input sensors are the same. They have the following differences:

In wiring: