// const int LED1 = 2;  // Fast blink LED
// const int LED2 = 4;  // Slow blink LED

// void setup() {
//   pinMode(LED1, OUTPUT);
//   pinMode(LED2, OUTPUT);
// }

// void loop() {
//   // Try to blink LED1 fast
//   digitalWrite(LED1, HIGH);
//   delay(200);   // BLOCKING
//   digitalWrite(LED1, LOW);
//   delay(200);   // BLOCKING

//   // Try to blink LED2 slow
//   digitalWrite(LED2, HIGH);
//   delay(1000);  // BLOCKING
//   digitalWrite(LED2, LOW);
//   delay(1000);  // BLOCKING
// }


const int LED1 = 2;  // Fast blink LED
const int LED2 = 4;  // Slow blink LED

unsigned long prev1 = 0;
unsigned long prev2 = 0;

void setup() {
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
}

void loop() {
  unsigned long now = millis();

  // Fast LED: toggle every 200 ms
  if (now - prev1 >= 200) {
    prev1 = now;
    digitalWrite(LED1, !digitalRead(LED1));
  }

  // Slow LED: toggle every 1000 ms
  if (now - prev2 >= 1000) {
    prev2 = now;
    digitalWrite(LED2, !digitalRead(LED2));
  }
}