Arduino - button value changes between 0 and 1 randomly?

I used Arduino to read the state from a button. The reading state changes between 0 and 1 randomly and constantly. The belows are Arduino code and the wiring diagram

#define BUTTON_PIN 7 void setup() { Serial.begin(9600); // initialize the button pin as a digital input pin pinMode(BUTTON_PIN, INPUT); } void loop() { // read the value of the button int buttonValue = digitalRead(BUTTON_PIN); Serial.println(buttonValue); }

Wiring Diagram

Arduino Button Wiring Diagram

Image is developed using Fritzing. Click to enlarge image

The output on Serial Monitor

COM6
Send
0 1 1 0 1 0 0
Autoscroll Show timestamp
Clear output
9600 baud  
Newline  

How to solve it?

Answer

Your problem is known as the floating input problem. When you connect an Arduino pin to a button/switch without using any pull-up or pull-down resistor, this problem will happen.

How to solve

There are three way to solve it with Arduino:

The below code used an internal pull-up resistor to solve the above problem

#define BUTTON_PIN 7 void setup() { Serial.begin(9600); // initialize the button pin as a digital input pin and enable the internal pull-up resistor pinMode(BUTTON_PIN, INPUT_PULLUP); } void loop() { // read the value of the button int buttonValue = digitalRead(BUTTON_PIN); Serial.println(buttonValue); }

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