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This example is for Wiring version 0024+. If you have a previous version, use the examples included with your software. If you see any errors or have comments, please let us know.

Serial Output by BARRAGAN
Demonstrates how to send data using the serial port. A computer running a Processing program receives the data from the serial port and fills a rectangle according to the value received.

    int switchpin = 0;            // switch connected to pin 0

    void setup() {
      pinMode(switchpin, INPUT);  // pin 0 as INPUT
      Serial.begin(9600);         // start serial communication at 9600bps
    }

    void loop() {
      if(digitalRead(switchpin) == HIGH)  // if switch is ON
      {
        Serial.print(1, BYTE);            // send 1 to Processing
      }else{
        Serial.print(0, BYTE);            // otherwise send 0 to Processing
      }
      delay(100);                         // wait 100ms for next print
    }

    /* Processing code for this example

    // switch serial
    // by BARRAGAN <http://barraganstudio.com>

    // Demonstrates how to read data from the Wiring I/O board, in order
    // to fill a rectangle on the screen using a lighter color when a switch
    // connected to the Wiring I/O board is pressed, and fill it with darker
    // color when the switch is released.

    // created 13 May 2004
    // revised 6 November 2009

    import processing.serial.*;

    Serial port;  // create serial port object
    int val;      // variable to receive data from the serial port

    void setup()
    {
      size(200, 200);
      noStroke();
      frameRate(10);

      // List all the available serial ports in the output pane.
      // You will need to choose the port that the Wiring 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.
      println(Serial.list());

      // Open the port that the Wiring board is connected to (in this case #2)
      // Make sure to open the port at the same speed Wiring is using (9600bps)
      port = new Serial(this, Serial.list()[2], 9600);
    }

    void draw()
    {
      if( 0 < port.available() )  // if data is available to read
      {
        val = port.read();        // read it and store it in 'val'
      }

      background(#222222);        // clear background

      if( val == 0 )              // if 0 was received
      {
        fill(#666660);            // set fill color
      }else{
        fill(#CCCCC0);            // set fill to a different color
      }

      rect(50, 50, 100, 100);     // draw square
    }

    */