Description
I decided to monitor the pressure placed on my wrist when using the mouse. And then visualize it on Processing in the form of a line graph. The setting is simply done by attaching a post-it beneath my mouse, and then tape the force sensing resistor on the post-it where my wrist usually rest on. Then the value read by Arduino is sent through serial port to Processing to draw the graph.
I used various colors representing different levels of pressure. The serial port is not very stable so I had to do some filters to take out values that might have been a bad transmission. When I tried to add a second value to the serial port (the photo cell) separated by a comma, Arduino started to lag whenever the Processing app is initiated. I spent quite some time debugging but couldn't get it to work.
Components
1 x Arduino UNO Board
1 x FSR
Code
Arduino
const int forcePin = 2;
int forceVal = 0;
void setup() {
Serial.begin(9600);
}
void loop() {
forceVal = analogRead(forcePin);
Serial.println(forceVal);
}
Processing
// Reference line graph example at
// http://www.learningprocessing.com
import processing.serial.*;
String portname = "/dev/tty.usbmodem1411";
Serial port;
String inputStr = "";
int pHeight = 400;
float[] vals;
int pressure, light;
void setup() {
println(3/4*pHeight);
size(600,400);
smooth();
port = new Serial(this, portname, 9600);
frameRate(30);
vals = new float[width];
for (int i = 0; i < vals.length; i++) {
vals[i] = pHeight;
}
}
void draw() {
background(255);
// Draw lines connecting all points
for (int i = 0; i < vals.length-1; i++) {
setStroke(vals[i+1]);
strokeWeight(2);
line(i,vals[i],i+1,vals[i+1]);
}
// Slide everything down in the array
for (int i = 0; i < vals.length-1; i++) {
vals[i] = vals[i+1];
}
}
void setStroke(float val){
//println(val);
float p = float(pHeight);
if(val > 3/4.0*p){
stroke(0,204,0);
} else if(val > p/2.0) {
stroke(225,225,0);
} else if(val > p/4.0) {
stroke(255,128,0);
} else {
stroke(255,0,0);
}
}
void serialEvent(Serial myPort) {
if (myPort.available() > 0) {
inputStr = myPort.readStringUntil('\n');
if(inputStr != null) {
//print(inputStr);
inputStr = trim(inputStr);
if(int(inputStr) < 1025) {
println(inputStr);
float val = pHeight - map(int(inputStr), 0, 800, 0, pHeight);
if(val - vals[width-2] < pHeight/2){
vals[width-1] = val;
}
} else {
println("N/A");
}
}
}
}
