Hi, I have written a program that reads an analog value through the serial port. According to this value, a specific sound file is loaded. The problem: the file keeps on playing as long as a signal is received. I understand why this happens, ut I can't fix it. I want the sound file to play only once, and then never again until a new value is received. How can I do this?

this is my code:


/*
*  pa_Potentiometer
*  
*  Reads the values which represent the state of a potentiometer
*  from the serial port and draws a graphical representation.
*
*  This file is part of the Arduino meets Processing Project.
*  For more information visit http://www.arduino.cc.
*
*  copyleft 2005 by Melvin Ochsmann for Malmö University
*
*/

// importing the processing serial class
import processing.serial.*;
import pitaru.sonia_v2_9.*;

// the display item draws background and grid
 DisplayItems di;

// definition of window size and framerate
 int xWidth = 768;
 int yHeight = 512;
 int fr = 1000;
 int lf = 3; //linefeed ascii
 
// attributes of the display
 boolean bck = true;
 boolean grid = true;
 boolean g_vert = true;
 boolean g_horiz = false;
 boolean g_values = true;
 boolean output = true;
 
// variables for serial connection, portname and baudrate have to be set
 Serial myPort;
 String portname = "/dev/tty.usbserial-351";  
 int baudrate = 9600;
 int value = 0;
 String buf="";
 int value1=0;  
 Sample sound1, sound2, sound3, sound4, sound5, sound6;

// variables to draw graphics
 int xpos;

// lets user control DisplayItems properties and value output in console
void keyPressed(){
 if (key == 'b' || key == 'B') bck=!bck;  // background black/white
 if (key == 'g' || key == 'G') grid=!grid;  // grid ON/OFF
 if (key == 'v' || key == 'V') g_values=!g_values;  // grid values ON/IFF  
 if (key == 'o' || key == 'O') output=!output;   //turns value output ON/OFF
}

void setup(){
 // set size and framerate
 size(xWidth, yHeight); framerate(fr);
 // establish serial port connection      
 myPort = new Serial(this, portname, baudrate);
 println(myPort);
 myPort.bufferUntil(lf);
 // create DisplayItems object
 di = new DisplayItems();
 //establish Sonia library
 Sonia.start(this,44100);
 sound1=new Sample("geluid1.wav");
 sound2=new Sample("geluid2.wav");
 sound3=new Sample("geluid3.wav");
 sound4=new Sample("geluid4.wav");
 sound5=new Sample("geluid5.wav");
 sound6=new Sample("geluid6.wav");
}

void drawPotiState(){
  noStroke();
  fill(0, 0, 255);
  // draw rectangfle at xpos
   rect(xpos, 0, width/32+(xpos/200), height);
   fill(255);
   // and xpos as text
   text(""+xpos , xpos, height/2);
}

void serialEvent(int serial){
 // if serial event is not a line break
 if(serial!=10) {        
   // add event to buffer
   buf += char(serial);          
   } else {
   // if serial is line break set value1 to buff and clear it
   value1 = int(buf);
   buf="";
   }
   // convert value1 to xpos
   xpos = constrain ( ( ((value1-100)*(width+100))/width )  ,0, width-12);
   if(output) println("xpos: "+xpos);
   // determine values for output
   if(value1<150){
     println("niks");
   } else if(value1<250){
     println("geluid1");
   } else if (value1<350){
     println("geluid2");
     sound2.play();
   } else if(value1<400){
     println("geluid3");
     sound3.play();
   } else if(value1<500){
     println("geluid4");
     sound4.play();
   } else if(value1<600){
     println("geluid5");
     sound5.play();
   } else if(value1<680){
     println("geluid6");
     sound6.play();
   }else{
    println("niks");
   }
   
}

// draw listens to serial port, draw
void draw(){
// listen to serial port and trigger serial event  
 while(myPort.available() > 0){
       value = myPort.read();
       serialEvent(value);
   }
// draw background, then PushButtonState and finally rest of DisplayItems  
   di.drawBack();
   drawPotiState();
   di.drawItems();  
}



Thanks a lot!