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Arduino - How to detect button press event
How to detect if a button is pressed and released using Arduino?
Answer
There are two ways to detect the button press event or release event:
- Using the button library (simple to use, recommended)
- Detecting the state's changes.
Let's see one by one.
The below wiring diagram will be used for both ways.
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Detecting the button press by using library
#include <ezButton.h>
ezButton button(7); // create ezButton object that attach to pin 7;
void setup() {
Serial.begin(9600);
button.setDebounceTime(50); // set debounce time to 50 milliseconds
}
void loop() {
button.loop(); // MUST call the loop() function first
if(button.isPressed())
Serial.println("The button is pressed");
if(button.isReleased())
Serial.println("The button is released");
}
※ NOTE THAT:
- In the above code, the button is debounced. See Why needs to debounce for buttons
- The library is non-blocking, we do NOT need to worry about blocking other code.
Detecting the button press by detecting the state's changes
#define BUTTON_PIN 7
int lastButtonState;
void setup() {
Serial.begin(9600);
pinMode(BUTTON_PIN, INPUT_PULLUP); // enable the internal pull-up resistor
lastButtonState = digitalRead(BUTTON_PIN);
}
void loop() {
// read the value of the button
int buttonState = digitalRead(BUTTON_PIN);
if (lastButtonState != buttonState) { // state changed
delay(50); // debounce time
if (buttonState == LOW)
Serial.println("The button pressed event");
else
Serial.println("The button released event");
lastButtonState = buttonState;
}
}
※ NOTE THAT:
- In the above code, the button is debounced. See Why needs to debounce for buttons
- The above code used the delay() function. This function blocks other code during the delay time. Depending on applicationm you may need to use millis() instead of delay().
⇒ Using the button library is the simplest way.
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