a.c

const int LED1 = PA1; // interrupt
const int LED2 = PA2; // 상시-주기적 toggling LED
const int BTN_LED = PB12; // -> LED1
const int BTN_MOTOR = PB13; // MOTOR_{A,B}

const int MOTOR_A = PA6;
const int MOTOR_B = PA7;

void handleLedISR() {
  digitalWrite(LED1, digitalRead(BTN_LED));
}

void setup() {
  pinMode(LED1, OUTPUT); pinMode(LED2, OUTPUT);
  pinMode(MOTOR_A, OUTPUT); pinMode(MOTOR_B, OUTPUT);

  pinMode(BTN_LED, INPUT_PULLUP); pinMode(BTN_MOTOR, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(BTN_INT), handleLedISR, CHANGE);
  digitalWrite(LED1, LOW); digitalWrite(LED2, LOW);
}

bool ledState = false;
unsigned long prevMillis = 0;
void loop() {
  unsigned long currentMillis = millis();

  if (currentMillis - prevMillis >= 500) {
    prevMillis = currentMillis;
    ledState = !ledState;
    digitalWrite(LED2, ledState ? HIGH : LOW);
  }

  digitalWrite(MOTOR_A, digitalRead(BTN_MOTOR) == LOW ? HIGH : LOW);
  digitalWrite(MOTOR_B, LOW);
}