#define LED_PIN PA5
#define BUTTON_PIN PA0

int LastButton

void setup() {
 pinMode(LED_PIN, OUTPUT);
 digitalWrite(LED_PIN, LOW);
 pinMode(BUTTON_PIN, INPUT_PULLUP);
 digitalWrite(BUTTON_PIN, LOW);
}

 void loop() {
  digitalWrite(BUTTON_PIN, INPUT_PULLDOWN);
  digitalWrite(LED_PIN, HIGH);

  digitalWrite(BUTTON_PIN, INPUT_PULLUP);
  digitalWrite(LED_PIN, LOW);

 }