Weird random data being sent from Arduino to Processing

Question

I'm trying to read data from a photocell resistor and my Arduino Decimila and then graph it in real-time with Processing.

Should be painfully simple; but its growing into a little bit of a nightmare for me.

code I'm running on my Arduino:

int photoPin = 0;

void setup()
{
  Serial.begin( 9600 );
}

void loop()
{
  int val = int( map( analogRead( photoPin ), 0, 1023, 0, 254 ) );
  Serial.println( val ); //sending data over Serial
}

code I'm running in Processing:

import processing.serial.*;

Serial photocell;

int[] yvals;

void setup()
{
  size( 300, 150 );
  photocell = new Serial( this, Serial.list()[0], 9600 );
  photocell.bufferUntil( 10 );
  yvals = new int[width];
}

void draw()
{
  background( 0 );
  for( int i = 1; i < width; i++ )
  {
    yvals[i - 1] = yvals[i];
  }

  if( photocell.available() > 0 )
  {
    yvals[width - 1] = photocell.read();
  }

  for( int i = 1; i < width; i++ )
  {
    stroke( #ff0000 );
    line( i, yvals[i], i, height );
  }
  println( photocell.read() ); // for debugging
}

I've tested both bits of code separately and I know that they work. It's only when I try to have the input from the Arduino going to Processing that the problems start.

When I view the data in Arduino's "Serial Monitor", I get a nice constant flow of data that seems to look valid.

But when I read that same data through Processing, I get a repeating pattern of random values.

Halp?

Answer 1

After a closer look at the resources at hand, I realized that the problem had already been solved for me by the folks over at http://arduino.cc

http://arduino.cc/en/Tutorial/Graph

Oh how much time I could have saved if I had seen that earlier.