const int ledPin = 13; // the pin that the LED is attached to

int incomingByte;      // a variable to read incoming serial data into


void setup() {


  // initialize serial communication:


  Serial.begin(9600);
Serial.println(" alku ");

  // initialize the LED pin as an output:


  pinMode(ledPin, OUTPUT);

}


void loop() {


  // see if there's incoming serial data:


  if (Serial.available() > 0) {


    // read the oldest byte in the serial buffer:


    incomingByte = Serial.read();


    // if it's a capital H (ASCII 72), turn on the LED:


    if (incomingByte == 'H') {


      digitalWrite(ledPin, HIGH);


    }


    // if it's an L (ASCII 76) turn off the LED:


    if (incomingByte == 'L') {


      digitalWrite(ledPin, LOW);


    }


  }

}


/* Processing code for this example


  // Mouse over serial


  // Demonstrates how to send data to the Arduino I/O board, in order to turn ON


  // a light if the mouse is over a square and turn it off if the mouse is not.


  // created 2003-4


  // based on examples by Casey Reas and Hernando Barragan


  // modified 30 Aug 2011


  // by Tom Igoe


  // This example code is in the public domain.


  import processing.serial.*;


  float boxX;


  float boxY;


  int boxSize = 20;


  boolean mouseOverBox = false;


  Serial port;


  void setup() {


    size(200, 200);


    boxX = width / 2.0;


    boxY = height / 2.0;


    rectMode(RADIUS);


    // List all the available serial ports in the output pane.


    // You will need to choose the port that the Arduino board is connected to


    // from this list. The first port in the list is port #0 and the third port


    // in the list is port #2.


    // if using Processing 2.1 or later, use Serial.printArray()


    println(Serial.list());


    // Open the port that the Arduino board is connected to (in this case #0)


    // Make sure to open the port at the same speed Arduino is using (9600bps)


    port = new Serial(this, Serial.list()[0], 9600);


  }


  void draw() {


    background(0);


    // Test if the cursor is over the box


    if (mouseX > boxX - boxSize && mouseX < boxX + boxSize &&


        mouseY > boxY - boxSize && mouseY < boxY + boxSize) {


      mouseOverBox = true;


      // draw a line around the box and change its color:


      stroke(255);


      fill(153);


      // send an 'H' to indicate mouse is over square:


      port.write('H');


    }


    else {


      // return the box to its inactive state:


      stroke(153);


      fill(153);


      // send an 'L' to turn the LED off:


      port.write('L');


      mouseOverBox = false;


    }


    // Draw the box


    rect(boxX, boxY, boxSize, boxSize);


  }
  */