Serial Communication

serial_communication.ino

Arduino code for serial communication

// set our sensor pin
int sensorPin = A1;
// set our sensor value
int sensorVal;

void setup() {
  pinMode(sensorPin, INPUT);
  Serial.begin(9600);

  // because this contains a `while` loop
  // `setup` will not complete until we've
  // connected
  establishContact();
}

void loop() {

  // better safe than sorry, only when we
  // know that there's a connection available
  if(Serial.available() > 0) {

    // now read the analog pin
    sensorVal = analogRead(sensorPin);

    // return the sensor value using the 
    // serial connection
    Serial.write(sensorVal);

    // hold your horses
    delay(10);
  }
}

// we use this function to initialize 
// contact ("handshake") with processing
void establishContact() {
  
  // keep trying until we've established
  // a connection
  while(Serial.available() <= 0) {
    
    // keep sending our handshake message
    // while we're waiting
    Serial.println("A");
    
    // add a bit of a delay to be friendly
    delay(300);
  }
}

serial_communication.pde

// Processing code for serial communication

// bring in the serial library
import processing.serial.*;

// variable for our serial communication port
Serial myPort;
int portIndex;

// this indicates whether we've made contact
// with the arduino
boolean firstContact = false;

// will store the sensor value when we're recieving data
int sensorVal;

void setup() {
  
  // setting my sketch size
  size(500, 500);
  
  // print a list of available serial ports
  printArray(Serial.list());
  
  // on my computer, arduino is connected to the 7th port
  portIndex = 7;
  
  // setup the serial port with the correct port number
  myPort = new Serial(this, Serial.list()[portIndex], 9600);
}

void draw() {
  // clear the background to BLACK
  background(0);
  
  // set styles
  noStroke();
  fill(255);
  
  // use the sensor input to draw a circle!
  ellipse(width/2, height/2, sensorVal, sensorVal);
    
  
}

// this function is called whenever data is recieved
// from the serial port
void serialEvent(Serial myPort) {

  // read the incoming byte into a variable
  int inByte = myPort.read();
 
  // if we haven't yet made contact yet
  if(firstContact == false) {
  
    // is this the phone call we've been waiting for?
    if(inByte == 'A') {
      
      // we've made contact!
      firstContact = true;

      // empty the serial buffer
      myPort.clear();
      
      // yes! hello!
      myPort.write('A');
    }
  
  } else {
    
    // helpful for debugging to keep a transcript
    println(inByte);
    
    // store in our global variable
    sensorVal = inByte;

    // keep the connection
    myPort.write('A');
  }
  
}