Assignment: Sensing PART II: Force Sensitive Resistors and Photocells
Collaborators:
Description
For this assignment, I designed a Smart Drink Coaster that measures how full or empty your glass is and gives a visual feedback of the levels with flashing lights. This DIY Smart Coaster can be used to indicate when you need to get a coffee refill, or signal to a bartender when your drink is dangerously close to empty.
Here, I have integrated both the Processing and the Mechanical parts of the assignment. For the Mechanical component, I extended the FSR circuit that we designed in class and attached it to a coaster. For the visualization, I made Processing receive serial input from the FSR connected to the Arduino. The visualization shows seven images of a bottle with varying levels of liquid in it. Initially, they are all grayed out (Actually, because the program is still running, the first image, which is that of an empty bottle alone is highlighted). When a mug is placed on it, the image corresponding to the liquid level in it lights up, and a flashing red lights points to it.
Components Used
Arduino
Force Sensitive Resistor (FSR)
Resistor
Coaster and a Cardboard support
Drink Mug
Wires
Code
Arduino Code
/*
* Resistive Sensor Input
* Takes the input from a resistive sensor, e.g., FSR or photocell
* Dims the LED accordingly, and sends the value (0-255) to the serial port
*/
int sensorPin = 0; // select the input pin for the sensor
int ledPin = 11; // select the output pin for the LED
int val = 0; // variable to store the value coming from the sensor
void setup() {
Serial.begin(9600);
}
void loop() {
val = analogRead(sensorPin); // read the value from the sensor, 0-1023
analogWrite(ledPin, val/4); // analogWrite (dimming the LED) can be between 0-255
delay(250);
Serial.println(val/4); // writing the value to the PC via serial connection
delay(50); // rest a little...
}
Processing Code
/*Created by Janani Vasudev
September 27,2009 */
import processing.serial.*;
String portname = "/dev/tty.usbserial-A70061pj";
Serial port;
String buf="";
int cr = 13; // ASCII return == 13
int lf = 10; // ASCII linefeed == 10
int val = 127;
int barWidth =6;
int xVal = 200;
int yVal = 420;
PImage img1;
PImage img2;
PImage img3;
PImage img4;
PImage img5;
PImage img6;
PImage img7;
PImage ball;
int prevFlag = 1;
int prevX = 82;
void setup()
{
//initialize canvas:
size(1245,700);
frameRate(10);
smooth();
background(40,40,40);
noStroke();
port = new Serial(this, portname, 9600);
//initialize the bottle images
img1 = loadImage("img1.gif");
img2 = loadImage("img2.gif");
img3 = loadImage("img3.gif");
img4 = loadImage("img4.gif");
img5 = loadImage("img5.gif");
img6 = loadImage("img6.gif");
img7 = loadImage("img7.gif");
ball = loadImage("ball.gif");
}
void draw()
{
/*image(img2,180,0);
image(img3,360,0);
image(img4,540,0);
image(img5,720,0);
image(img6,900,0);
image(img7,1080,0); */
}
// called whenever serial data arrives
void serialEvent(Serial p)
{
int c = port.read();
int x = 0;
int flag = 0;
if (c != lf && c != cr)
{
buf += char(c);
}
if (c == lf)
{
int val = int(buf);
println("val="+val);
buf = "";
if(val >= 0 && val< 10)
{
noTint();
image(img1,0,0);
tint(70,50);
image(img2,180,0);
image(img3,360,0);
image(img4,540,0);
image(img5,720,0);
image(img6,900,0);
image(img7,1080,0);
float m = millis();
fill(m % 180, 0, 0);
//fill(40,40,40);
noStroke();
ellipse(82,400,50,50);
x = 82;
flag = 1;
}
else if(val >= 10 && val <45)
{
noTint();
image(img2,180,0);
tint(70,50);
image(img1,0,0);
image(img3,360,0);
image(img4,540,0);
image(img5,720,0);
image(img6,900,0);
image(img7,1080,0);
float m = millis();
fill(m % 180,0,0);
//fill(40,40,40);
noStroke();
ellipse(260,400,50,50);
x = 260;
flag = 2;
}
else if(val >=45 && val<80)
{
noTint();
image(img3,360,0);
tint(70,50);
image(img1,0,0);
image(img2,180,0);
image(img4,540,0);
image(img5,720,0);
image(img6,900,0);
image(img7,1080,0);
float m = millis();
fill(m % 180,0,0);
//fill(40,40,40);
noStroke();
ellipse(440,400,50,50);
x = 440;
flag = 3;
}
else if(val >= 80 && val<90)
{
noTint();
image(img4,540,0);
tint(70,50);
image(img1,0,0);
image(img2,180,0);
image(img3,360,0);
image(img5,720,0);
image(img6,900,0);
image(img7,1080,0);
float m = millis();
fill(m % 180,0,0);
//fill(40,40,40);
ellipse(620,400,50,50);
//tint(255,255);
noStroke();
x = 620;
flag = 4;
}
else if(val >= 90 && val<110)
{
noTint();
image(img5,720,0);
tint(70,50);
image(img1,0,0);
image(img2,180,0);
image(img3,360,0);
image(img4,540,0);
image(img6,900,0);
image(img7,1080,0);
float m = millis();
fill(m % 180,0,0);
//fill(40,40,40);
noStroke();
ellipse(800,400,50,50);
x=800;
flag = 5;
}
else if(val >= 110 && val<= 120)
{
noTint();
image(img6,900,0);
tint(70,50);
image(img1,0,0);
image(img2,180,0);
image(img3,360,0);
image(img4,540,0);
image(img5,720,0);
image(img7,1080,0);
delay(1000);
float m = millis();
fill(m % 180,0,0);
noStroke();
//fill(40,40,40);
ellipse(980,400,50,50);
x=980;
flag = 6;
}
else if(val > 120)
{
noTint();
image(img7,1080,0);
tint(70,50);
image(img1,0,0);
image(img2,180,0);
image(img3,360,0);
image(img4,540,0);
image(img5,720,0);
image(img6,900,0);
float m = millis();
fill(m % 180,0,0);
//fill(40,40,40);
noStroke();
ellipse(1160,400,50,50);
x=1160;
flag = 7;
}
if (flag != prevFlag) {
fill(40, 40, 40);
noStroke();
ellipse(prevX, 400, 50, 50);
}
prevFlag = flag;
prevX = x;
// prevY = y;
}
}
