Lab 4: FSR Pac-Man Display

This lab uses a force sensitive resistor embedded in a stuffed animal to register serial input.  When the animal is squeezed, a red LED on the breadboard blinks in direct proportion to how hard the user squeezes to the toy: the harder the user squeezes, the longer the interval between blinks.

Serial output is then transferred to Processing, which uses to amount of pressure applied to draw a Pac-Man shape near the center of the display (modification of the "Ball Paint" code distributed in lab last week.)  The harder the user squeezes the toy, the larger Pac-Man becomes.

Components Used:

1 - Arduino UNO
1 - Solderless breadboard
1 - Red LED
1 - 220-ohm resistor (used with LED)
1 - Force Sensitive Resistor
1 - 10k-ohm resistor (used with FSR)
1 - Adventure Time "Jake" (Cartoon Network) plush toy
1 - USB Power Supply

Code:

Arduino Code

int led = 10;

int sensorpin = A0;
int sensorval = 0;

void setup() {               
  Serial.begin(9600);
  pinMode(led, OUTPUT);     
}

void loop() {
  sensorval = analogRead(sensorpin);
  Serial.println( sensorval);
  digitalWrite(led, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(sensorval);               // wait for a second
  digitalWrite(led, LOW);    // turn the LED off by making the voltage LOW
  delay(sensorval);               // wait for a second
  sensorval = analogRead(sensorpin);
}

Processing Code

/*
 * Arduino Ball Paint
 * (Arduino Ball, modified 2008)
 * ----------------------
 *
 * Draw balls randomly on the screen, size controlled by a device
 * on a serial port.  Press space bar to clear screen, or any
 * other key to generate fixed-size random balls.
 *
 * Receives an ASCII number over the serial port,
 * terminated with a carriage return (ascii 13) then newline (10).
 *
 * This matches what Arduino's " Serial.println(val)" function
 * puts out.
 *
 * Created 25 October 2006
 * copyleft 2006 Tod E. Kurt <tod@todbot.com
 * http://todbot.com/
 */
import processing.serial.*;
// Change this to the portname your Arduino board
String portname = "COM3"; // or "COM5"
Serial port;
String buf="";
int cr = 13;  // ASCII return   == 13
int lf = 10;  // ASCII linefeed == 10
void setup() {
  size(1000,700);
  frameRate(25);
  smooth();
  background(0,0,0);
  noStroke();
  port = new Serial(this, portname, 9600);
}
void draw() {
}
void keyPressed() {
  if(key == ' ') {
    background(0,0,0);  // erase screen
  }
  else {
    int x = int(random(450,550));
    int y = int(random(300,400));
    drawball(x,y, 25);
  }
}
// draw balls
void drawball(int x, int y, int r) {
  for (int i=0; i<100; i++ ) {
    fill(255-i,255-i,0);
    arc(x,y,r,r,PI/4,7*PI/4);
  }

}
// called whenever serial data arrives
void serialEvent(Serial p) {
  int c = port.read();
  if (c != lf && c != cr) {
    buf += char(c);
  }
  if (c == lf) {
    int val = int(buf);
    println("val="+val);
    int x = int(random(450,550));
    int y = int(random(300,400));
    drawball(x,y,val);
    buf = "";
    background(0,0,0);  // erase screen
  }
}