#define LED_PIN PA7   // LED connected to PA7

void setup() {
  pinMode(LED_PIN, OUTPUT);   // Set LED pin as output
}

void loop() {
  digitalWrite(LED_PIN, HIGH);   // LED ON
  delay(100);                    // wait 500 ms
  digitalWrite(LED_PIN, LOW);    // LED OFF
  delay(100);                    // wait 500 ms
}