boolean wechsel = true;
boolean swap = true;
int var = 0;
void setup() {
  pinMode(PA5, OUTPUT);
  // put your setup code here, to run once:
  Serial.begin(115200);
  static HardwareTimer tm = HardwareTimer(TIM1);
  tm.setOverflow(2,HERTZ_FORMAT);
  tm.attachInterrupt(zeit);
  tm.resume();
  attachInterrupt(digitalPinToInterrupt(PA1), blink, RISING);
}

void loop() {
  // put your main code here, to run repeatedly:
  delay(10); // this speeds up the simulation
}

void zeit(){
  if(swap){
    if(wechsel){
      digitalWrite(PA5, HIGH);
      wechsel = false;
   }
   else{
     digitalWrite(PA5, LOW);
     wechsel = true;
   }
  }
  else{
    while(var<5){
    digitalWrite(PA5,HIGH);
    }
    var = 0;
  }
}

void blink(){
  swap= false;
  var++;
}