char blueToothVal; //Values should be sent using Bluetooth 
char lastValue;   //The last status of the LED (on/off) will be logged in this variable 
 
void setup(){
 Serial.begin(9600);  //Serial Monitor will be started, Baudrate will be 9600
 pinMode(8,INPUT);  //Pin PD7 will be declared as OUTPUT
}
 
void loop(){
  if(Serial.available()) //if there are data received...      
{
    blueToothVal=Serial.read();//..data should be readed
  }
  if (blueToothVal=='1') //if the Bluetooth modul recieves „1“ ..
  {
    digitalWrite(13,HIGH);   //...red LED should switch on....
    if (lastValue!='1') //if the last recieved value was „1“ ...
      Serial.println(F("LED is on")); //..than show "LED is on" on the Serial Monitor
    lastValue=blueToothVal;
  }
  else if (blueToothVal=='0') //if the Bluetooth Modul recieves „0“...
  {           
    digitalWrite(13,LOW);  //.. LED should not light up
    if (lastValue!='0')  //ir the last received value was „0“ ...
      Serial.println(F("LED is off")); //... on the Serial Monitor should be displyed „LED is off“ 
    lastValue=blueToothVal;
  }
 }