#define IR_PIN PA0
#define LED_PIN PA5

void setup(void)
{
  pinMode(IR_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
}

void loop(void)
{
  int irState = digitalRead(IR_PIN);

  if (irState == LOW) {        // Object detected
    digitalWrite(LED_PIN, HIGH);
  } else {                     // No object
    digitalWrite(LED_PIN, LOW);
  }
}