How Do I Blink Without delay()?

Use millis to track time and toggle the LED when enough time has passed.

blink_without_delay.ino

cpp

const int ledPin = 13;
unsigned long last = 0;
const unsigned long interval = 500;
bool state = false;

void setup() {
  pinMode(ledPin, OUTPUT);
}

void loop() {
  if (millis() - last >= interval) {
    last = millis();
    state = !state;
    digitalWrite(ledPin, state);
  }
}

Why this helps

The loop keeps running, so you can read buttons and sensors at the same time.

Bottom line

millis lets you blink and still do other work.