How To Install A Toggle Switch On A Lamp

Arduino - Button Toggle LED

In a previous tutorial, We have learned how to turn on the LED if the button is pressed, and turn off LED if the button is released. In this tutorial, We are going to learn how to toggle LED each time button is pressed.

The tutorial includes two main parts:

Button toggles LED without debouncing.
Button toggles LED with debouncing.

1	×	Arduino UNO or Genuino UNO
1	×	USB 2.0 cable type A/B
1	×	Button
1	×	LED
1	×	220 ohm resistor
1	×	Breadboard
4	×	Jumper Wires

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If you do not know about LED and button (pinout, how it works, how to program ...), learn about them in the following tutorials:

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const int BUTTON_PIN = 7; const int LED_PIN = 3; int ledState = LOW; int lastButtonState; int currentButtonState; void setup() { Serial.begin(9600); pinMode(BUTTON_PIN, INPUT_PULLUP); pinMode(LED_PIN, OUTPUT); currentButtonState = digitalRead(BUTTON_PIN); } void loop() { lastButtonState = currentButtonState; currentButtonState = digitalRead(BUTTON_PIN); if(lastButtonState == HIGH && currentButtonState == LOW) { Serial.println("The button is pressed"); ledState = !ledState; digitalWrite(LED_PIN, ledState); } }

Connect Arduino to PC via USB cable
Open Arduino IDE, select the right board and port
Copy the above code and open with Arduino IDE
Click Upload button on Arduino IDE to upload code to Arduino
Keep pressing the button several seconds and then release it.
See the change of LED's state

Read the line-by-line explanation in comment lines of code!

In the code, ledState = !ledState is equivalent to the following code:

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if(ledState == LOW) ledState = HIGH; else ledState = LOW;

※ NOTE THAT:

In practice, the above code does not work correctly sometimes. To make it always work correctly, we need to debounce for the button. Debouncing for the button is not easy for beginners. Fortunately, thanks to the ezButton library, We can do it easily.

Why do we need debouncing? ⇒ see Arduino - Button Debounce tutorial

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#include <ezButton.h> const int BUTTON_PIN = 7; const int LED_PIN = 3; ezButton button(BUTTON_PIN); int ledState = LOW; void setup() { Serial.begin(9600); pinMode(LED_PIN, OUTPUT); button.setDebounceTime(50); } void loop() { button.loop(); if(button.isPressed()) { Serial.println("The button is pressed"); ledState = !ledState; digitalWrite(LED_PIN, ledState); } }

Install ezButton library. See How To
Copy the above code and open with Arduino IDE
Click Upload button on Arduino IDE to upload code to Arduino
Press button several times
See the change of LED's state

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Most electronic products have a reset button. Additionally, the button also keeps other functionalities in many products.

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