blink2.ino

#include <dummy.h>

const int SWITCH_PIN = 0;
const long BLINK_INTERVAL = 250;

int ledState = LOW;
bool isBlinking = false;
unsigned long previousMillis = 0;

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(SWITCH_PIN, INPUT_PULLUP);
}

void loop() {
  if (digitalRead(SWITCH_PIN) == LOW) {
    if (isBlinking == false) {
      previousMillis = 0;
    }
    isBlinking = true;
    unsigned long currentMillis = millis();
    if(currentMillis - previousMillis >= BLINK_INTERVAL) {
      previousMillis = currentMillis;   
      if (ledState == LOW) {
        ledState = HIGH;
      }
      else {
        ledState = LOW;
      }
      digitalWrite(LED_BUILTIN, ledState);
    }
  }
  else {
    isBlinking = false;
    digitalWrite(LED_BUILTIN, HIGH);
    delay(100);
  }
}