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byte lineEnding = 0x0A;       

                              //Data array that the received info from android app is recorded. Every byte corresponds to a digital pin.
byte readBuffer[15];          //For example readBuffer[5] is for digital pin 5. 
byte defaultByte = 0x10;      //On start all arduino digital pins must be input for electrical protection.
                              //Pins 0 and 1 are used for serial comminations. So read
void setup() {   
  
for (int i=0; i < sizeof(readBuffer)-1 ; ++i) {
      readBuffer[i] = defaultByte;} 
      
  Serial.begin(9600);
}

void loop() {              
      if (Serial.available() > 14) {
          Serial.readBytesUntil(lineEnding, (char*) readBuffer, 15);
     
          for (int i=2; i < sizeof(readBuffer)-1 ; i++ ) {                
              if( bitRead(readBuffer[i], 4 )) { pinMode(i,INPUT);} else { pinMode(i,OUTPUT);} 
          }
      
         for (int i=2; i < sizeof(readBuffer)-1 ; i++ ) {                
              if( bitRead(readBuffer[i], 0 )) { digitalWrite(i,HIGH);} else { digitalWrite(i,LOW);}
          }  
      }
}