Tact Switch

A switch used to control circuits and other electronic components.

It can be connected to a digital pin on Arduino and used as an input signal.

A button cap can be attached for use.

How to Use

• [1, 3] and [2, 4] are connected together, and pressing the button connects all numbers.

Connection and Example of Use

• When the switch is pressed, an LED lights up. No separate coding is provided.

Execution Result

Floating Phenomenon and Pull-up, Pull-down Resistors

Floating Phenomenon

The floating phenomenon refers to the state where the input pin of a switch or button is not properly connected to any voltage.

In the circuit above, when the switch is connected, a 5V (HIGH) signal is connected to pin 6.

However, when the switch is not connected, it's unclear whether pin 6 is HIGH or LOW.

Even without pressing the switch, the serial monitor may show the output of pin 6 as 1 (HIGH).

To solve this floating phenomenon, pull-up or pull-down resistors are needed.

Pull-up Resistor

A resistor is added between the input pin and 5V.

When the switch is open, it remains 1 (HIGH), and when the switch is closed, it is shorted to GND, maintaining 0 (LOW).

Pull-down Resistor

A resistor is added between the input pin and GND.

When the switch is open, it is shorted to GND, maintaining 0 (LOW), and when the switch is closed, it remains 1 (HIGH).

Arduino Internal Pull-up Resistor (INPUT_PULLUP)

Arduino has a built-in pull-up resistor.

When setting the digital input pin mode, using 'INPUT_PULLUP' allows you to use the digital pin as a pull-up resistor without adding an external resistor.

Setting pinMode to INPUT_PULLUP without adding a separate resistor yields the same result as using a pull-up resistor.