Processing with Phidgets

Source Code with Classes for Operating Phidgets from Processing

• Accelerometer
• Advanced Servo
• Encoder
• Interface Kit
• Motor Controller

Sample Sketches

• testPhidgetAccelerometer.zip
• testPhidgetAdvancedServo.zip
• testPhidgetEncoder.zip
• testPhidgetIK.zip
• testPhidgetMotorControl.zip

General Instructions

1. Install phidget drivers for your computer from http://www.phidgets.com/ - drivers tab.
2. Make a folder to keep your phidget-related files in. This will contain files that you will re-use for phidget projects, not your Processing sketches.
3. Download phidget21.jar from http://www.phidgets.com/ - programming tab. Put it in your phidget folder.
4. Download the Processing code for the phidgets you plan to use from this page. Put them in your phidget folder.
5. Create a new Processing sketch. Save the sketch, giving it a suitable name.
6. From the Sketch menu in Processing, select Add File ... From the file selection dialogue, select phidget21.jar from your folder of phidget-related files. This will add a folder name code to your Processing sketch folder, and a copy phidget21.jar will appear there.
7. From the Sketch menu in Processing, select Add File ... From the file selection dialogue, select the Processing code for your phidget, e.g., phidgetIK.pde. You will see a new file tab appear for your sketch with the Processing code, and the file will be copied to your sketch folder.
8. Repeat the previous step for each type of phidget that you will use.

Your sketch is now ready for you to start writing code that uses the phidgets.

The following example illustrates how to write Processing code that uses phidgets. It is based on testPhidgetAccelerometer.zip.

1. Every phidget needs an object to operate it, so create the object variable:

phidgetAccelerometer accelerometer;

2. You need to create an instance of the accelerometer object. The example does this in setup().

void setup() {
  ...
  // get phidget IK started and wait up to 1s for attach
  accelerometer = new phidgetAccelerometer();
  ...
}

void setup() {
  ...
  // get phidget IK started and wait up to 1s for attach
  accelerometer = new phidgetAccelerometer( 12345 );
  ...
}

3. It is not strictly necessary, but I like to wait for the phidget to attach in setup(). When the phidget is attached it means it is plugged in by USB and ready for the program to use it.

void setup() {
  ...
  // get phidget IK started and wait up to 1s for attach
  accelerometer = new phidgetAccelerometer();
  accelerometer.waitForAttachment( 1000 );
  ...
}

4. In draw(), check to see if the phidget is attached. If it is, display a green circle, otherwise display a red circle.

void draw() {
  ...
  // show attach status
  if ( accelerometer.isAttached() ) fill( 0, 255, 0 );
  else fill( 255, 0, 0 );
  noStroke();
  ellipse( 20, 20, 10, 10 );
  ...
}

5. Find and display the serial and version numbers for the accelerometer phidget.

void draw() {
  ...
  // show serial number and version
  fill(0);
  text( accelerometer.serial(), 40, 25 );
  text( accelerometer.version(), 40, 35 );
  ...
}

6. Display the acceleration data as a bar graph. The code uses the getAxisCount() to determine the number of axes to display acceleration data for, allowing a for loop to iterate through the axes.

void draw() {
  ... 
  // show accelerations
  for( int i = 0; i < accelerometer.getAxisCount(); i++ ) {
    ...
  }
  ...
}

void draw() {
  ... 
  // show accelerations
  for( int i = 0; i < accelerometer.getAxisCount(); i++ ) {
    float xc = 30.0 + i * 60.0;
    float yc = 140.0;
    ...
  }
  ...
}

void draw() {
  ... 
  // show accelerations
  for( int i = 0; i < accelerometer.getAxisCount(); i++ ) {
    ...
    float y = map( accelerometer.getAcceleration( i ),
        accelerometer.getAccelerationMin( i ), accelerometer.getAccelerationMax( i ), 230.0, 50.0 );
    ...
  }
  ...
}

void draw() {
  ... 
  // show accelerations
  for( int i = 0; i < accelerometer.getAxisCount(); i++ ) {
    ...
    noFill();
    stroke( 0 );
    line( xc, yc, xc, y );
    fill( #0000ff );
    noStroke();
    ellipse( xc, y, 10, 10 );
  }
  ...
}

7. It is best to use the close() method for the phidget object explicitly. It closes the phidget connection nicely, which will not happen automatically when Processing/Java deletes your phidget object. I used a keyPressed event to trigger the close() method and to shut down the program.

void draw() {
  ... 
  if (keyPressed) {
    accelerometer.close();
    exit();
  }
}

Documentation

The phidget classes currently available are:

• phidgetAccelerometer
• phidgetAdvancedServo
• phidgetEncoder
• phidgetIK
• phidgetMotorControl

Each phidget class has two constructors as given below (TYPE is one of Acclerometer, AdvancedServo, Encoder, IK, or MotorControl).

Every phidget class has these methods.

The following are methods specific to each phidget type.