Arduino Toggle LED with a push button

Toggle_push_button_LED.ino

/*
  Fade
  This example shows how to fade an LED on pin 9
  using the analogWrite() function.

  The analogWrite() function uses PWM, so if  you
  want to change the pin you're using, be  sure to
  use another PWM capable pin. On most  Arduino,
  the PWM pins are identified with   a "~" sign,
  like ~3, ~5, ~6, ~9, ~10 and ~11.
*/

#include <Arduino.h>
#include <OneButton.h> // Library: https://github.com/mathertel/OneButton

#define BUTTON_PIN A1
#define LED_PIN 3

typedef enum {
  OFF,  // set LED "OFF".
  ON    // set LED "ON"
} states;

OneButton button = OneButton(
  BUTTON_PIN,  // Input pin for the button
  true,        // Button is active LOW
  true         // Enable internal pull-up resistor
);

// old version:
//OneButton button(BUTTON_PIN, true);

states state = OFF;

int brightness = 0;
int inc = 5;


void setup() {
  pinMode(LED_PIN, OUTPUT);
  button.attachClick(handleClick);
  // set 80 msec. debouncing time. Default is 50 msec.
  //button.setDebounceTicks(80); // no need..
  Serial.begin(9600);
}

void loop() {
  button.tick(); // check if button was pushed
  
  if (state == ON) {
    for (brightness = 0; brightness <= 255; brightness += inc) {
      analogWrite(LED_PIN, brightness);
      delay(30); // Wait for 30 millisecond(s)
      button.tick(); // check if button was pushed
    }
    for (brightness = 255; brightness >= 0; brightness -= inc) {
      analogWrite(LED_PIN, brightness);
      delay(30); // Wait for 30 millisecond(s)
      button.tick(); // check if button was pushed
    }
  }
}

// Handler function for a single click:
static void handleClick() {
  Serial.println("Clicked!");
  if (state == OFF) {
    Serial.println("ON!");
    state = ON;
  } else {
    Serial.println("OFF!");
    state = OFF;
  }
}