Juan Ferrer and Jorge Cases built a liquid tester, with only two wires and a resistor, which can measure the resistance of a liquid. Because every liquid has a different resistance you can separate different drinks like water or orange juice. With some Processing code you can do something nice with those values.

How to make your own liquid tester:
You need an Arduino, some wires and a 10K resistor.
Upload the standardFirmata to the Arduino, read this for more info.

// Detector de Liquidos (Liquid Detector)
// By Juan Ferrer and Jorge Cases
// open this file in Processing and upload the Standard Firmata to your Arduino
// connect the wires to the analog input port number 0

import processing.serial.*;
import cc.arduino.*;

Arduino arduino;

color off = color(4, 79, 111);
color on = color(84, 145, 158);

color blueColor = color(0,0,250);
color orangeColor = color(255,128,0);

int heightVal = 280;
int widthVal = 470;
int adjust = 20;
PFont fontA;

void drawGraph() {
  line(adjust,adjust,adjust,heightVal-(adjust*2));
  line(adjust,heightVal-(adjust*2),widthVal-(adjust*2),heightVal-(adjust*2));
}

void setup() {
  size(widthVal, heightVal);
  arduino = new Arduino(this, Arduino.list()[0], 115200);
  fontA = loadFont("CourierNew36.vlw");
  textFont(fontA, 32);
}

void draw() {
  background(off);
  stroke(on);

  drawGraph();
  int value = arduino.analogRead(0);

  if (value < 980 && value > 900) {
    fill(blueColor);
    text("this is water", 200, 90);
  } else if (value<800 && value > 700) {
    fill(orangeColor);
    text("this is orange juice", 200, 90);
  }
  else {
    fill(off);
    text("", 200, 90);
  }
  println(value);
  rect(adjust,heightVal-(adjust*2),50,-(heightVal-(adjust*2))*value/1024);
  delay(500);
}

download processing.org code

Campus party is the biggest technology event in the world, it is sort of an oversized LAN-party with more than 6000 geeks. Besides sitting in front of your computer and playing games you can also attend some workshops and listen to various speakers. The Campus Party was held in one of the beautiful buildings from ‘Ciudad de las Artes y las Ciencias ‘ (city of arts and sciences).

The part of Campus Party where the interactive installations were shown was the ‘Campus Futuro‘ section, there were some other cool interactive projects like the Wiispray, Move and some robots. The entry was free to this section so a lot of people entered.

The building was open from 10:00 till 21:00 seven days a week. It was a good test case to see how Gyro worked under these ‘extreme’ conditions. Although it still is a prototype, it worked quite well and was easy to fix the problems which occurred.
It was a great week and I’am full of ideas and improvements for the next version of Gyro.

What is it used for
Most people are using 3D printing for fun or for prototyping. You are able to make almost every object that you can think of. It’s even possible to make objects which are not produce-able with ordinary production methods like shapes inside a bigger shape.

Gyro project
For my Gyro project I used a 3D printer for a plastic part that you can click on top of a Powerball. This part hold the sensor which measures the speed.


I used Cinema 4D (C4D) to build the object, Cinema 4D is probably not the best tool to do 3D modeling for 3D printers, there are better (CAD) tools which have more precise measurement tools like Solid Work. C4D is a very user friendly program and it runs on PC and Mac. I exported the file as a collada file from C4D. I opened the file in Meshlab to check for errors like inverted normals and holes, from Meshlab I exported the object as a STL file, and uploaded it to Shapeways.

There are some different places were you can print your 3D models, all around the world (also in Amsterdam) there are Fablabs where you can use a 3D printer to print out your models. You can also upload your file to an online 3D printing company and they will print your models. My objects were printed at ‘Shapeways‘. Although it is a Dutch company, you pay in US dollars and worldwide shipping is included if you order has a minimum of $25,-.

At Shapeways there are some different materials which you can choose, like black, white and transparent. All the materials are not as smooth as normal plastic, that’s a characteristic of 3D printers. I used very fine sandpaper to smooth-en the plastic part. Sandpapering works, but there are always parts you can’t sandpaper, because it is impossible to reach.

I think 3D printing is great for prototyping and I am certainly going to use it in some future projects.

Use this script if you always wanted to now at which time your colleagues enter and leave the office.

What does it do?

It will scan the local network every minute for predefined computernames. If this returns a true than the computer is switched on and the colleague is probably at the office and it will send ‘John Doe has entered the office’ to a Twitter page.

How can I use it

Currently the script is only tested on Mac OS, it shouldn’t be so hard to convert it to a script that is working under Windows, ‘nmblookup’ should be replaced with ‘ping’. Please leave a comment at this page if you have this script working in Windows.

Source files:

» Download Processing code + PHP source files

After @BarackObama, @BritneySpears and @oprah it is now time for the coffeemachine to get on Twitter and add some meaning full words.

What does it do?

It will tweet “the coffee machine says: I’m making coffee” if you turn on the coffeemachine, if you switch it off it will tweet “the coffee machine says: someone switched me off”.

How does it work?

This is an overview of the hardware/software/services I used:
Sensor > Arduino > Processing > PHP > Twitter

A LDR (light dependent resistor) is glued on the on/off led of the coffeemachine. When the coffeemachine is switched on the led turns on, the ldr detects this light. This LDR is connected to an Arduino microcontroller, Processing reads the value from the Arduino using Firmata and Processing sends this to a php file which will send it to Twitter.

How to build your own?

Although it looks a bit overwhelming it is very easy to build your own tweeting ‘whatever’ thing, All hardware, software and scripts I used to build this are opensource. I just hacked everything together.
You will need the following:

• Arduino board + software
• LDR (or an other analog sensor)
• Processing (Processing.org)
• webhosting with php support
• a Twitter account

Source files:

» Download Processing code + PHP source files

What do I need to do to get this working on my computer?

I use the Arduino Library for Processing and the Firmata firmware for the Arduino (included in Arduino 12 or higher).

1) Unzip the file ‘processing-arduino2.zip’ and copy the “arduino” folder into the “libraries” sub-folder of your Processing Sketchbook. (You can find the location of your Sketchbook by opening the Processing Preferences. If you haven’t made a “libraries” sub-folder, create one.)

2) Start the Arduino application and open the Examples > Library-Firmata > StandardFirmata sketch, and upload it to the Arduino board.

3) Upload the php files on your (php enabled) server in a folder called ‘twittertest’ (for example)
Open the file ‘coffeemachine_processing.pde’ with Processing, and edit the following lines:
- change the variable:
twitterPassword = "yourTwitterPassword";
- change the portnumber for the Arduino:
arduino = new Arduino(this, Arduino.list()[2]);
- change the url:
new URL("http://www.yourdomain.com/twittertest/insertTwitterMsg.php?pass="+twitterPassword+"&msg="+msg).openStream();

4) Open the file ‘insertTwitterMsg.php’ with a text editor and change the variable ‘$twitterUsername’ in your Twitter username.?

5) Open the file ‘ coffeemachine_processing.pde’ in Processing and press ‘run’. Now you should have your own Tweeting arduino sensor.

Instead of a coffeemachine there are hundreds of other possibilities, you can connect almost every sensor or object to Twitter, and build your own ‘internet of things’.
Next week I will post a ‘Who’s at the Office’ Processing script that scans computernames in a local network, so stay tuned…

The Processing source file ‘coffeemachine_processing.pde’:

/*
coffeemachineProcessing - receives Arduino input from sensor and sends a message to Twitter
Date: 05-2009
Copyleft by Eric Holm 

http://ericholm.nl/blog

*/

// import the Serial port library
import processing.serial.*;
// import the firmata arduino library
import cc.arduino.*;

Arduino arduino;
int sensorPin = 0;    // Analog input pin
int sensorValue = 0;  // value read from analog input
Boolean isBusy = false;
String twitterPassword;

void setup() {
  // CHANGE YOUR TWITTER PASSWORD
  twitterPassword = "yourTwitterPassword";

  // CHANGE YOUR PORT NUMBER
  arduino = new Arduino(this, Arduino.list()[2]); // v2
  arduino.pinMode(sensorPin, Arduino.INPUT);
}

void draw() {
  sensorValue = arduino.analogRead(sensorPin); // read the analog value
  // if the analog value is below a certain value
  if (sensorValue < 930) {
    switchCoffee(true);
  }
  // if the analog value is above a certain value
  if (sensorValue > 800) {
    switchCoffee(false);
  }
  // for testing the value
  println(sensorValue);
  // delay for 5 seconds
  delay(5000);
} 

public void switchCoffee(Boolean switchState){
  if (switchState) {
    if (isBusy == false) {
      // switch on the led on port 13 of the arduino
      arduino.digitalWrite(13, Arduino.HIGH);
      // for testing inside the Processing IDE
      println("the coffee machine says: I'm making coffee");
      sendToTwitter("I%20am%20making%20coffee");
      isBusy = true;
    }
  } else {
  if (isBusy == true) {
     // switch on the led on port 13 of the arduino
     arduino.digitalWrite(13, Arduino.LOW);
     // for testing inside the Processing IDE
     println("the coffee machine says: someone switched me off");
     sendToTwitter("someone%20switched%20me%20off");
     isBusy = false;
    }
  }
}

public void sendToTwitter(String msg){
  try {
    // calls the PHP script on your own domain with the 'msg' string as a parameter
    new URL("http://www.yourdomain.com/twittertest/insertTwitterMsg.php?pass="+twitterPassword+"&msg="+msg).openStream();
    // wait 3 seconds..
    delay(3000);
  }
  catch (Exception theException) {
    theException.printStackTrace();
  }
}

The Hot100 are the most talented, newly introduced, most passionated and promising up-and-coming creative media talent.
According to the: Virtueel Platform

During Picnic’08 there was a special day for all the ‘hot’ people.
I presented my Gyro project, and tried to give a practical demo within 3 minutes.

The Golden Dot is a yearly showcase and award ceremony for excellent student projects from the Institute for Interactive Media at the University of Applied Sciences in Amsterdam.
This year, the Golden Dot will take place at Hotel Arena in Amsterdam, on 10 June 2008. In the afternoon, fourteen projects will be pitched before an official jury. That evening, the award ceremony will take place, hosted by Dennis Weening, Mtv Europe.
from: networkcultures.org

Although there was not much competition in the graduation year, the Gyro project has won a ‘Golden Dot’ in the category ‘graduation project’.
I think the Gyro project was a nice and fun project to present and it was certainly something different than ‘a website’. It has struck me that there where quite a lot of presentations which were almost the same.

Presentation files: Arduino Introduction (pdf, 0,4 MB)

I also showed a demo of my pong with the Arduino and an accelerometer,
not really a replacement for the wii controller, but it’s a start

For the geeks:
I used a 2-axis digital accelerometer called “adxl202 JQC” from Analog Device. For reading the sensor I slighty modified the standard “accelerometer_memsic2125″ code.

For communicating between the Arduino and flash I used the SerialServer from Dan O’Sullivan. It’s not really simple to setup but once its working it works great.

for more information about Arduino check the ‘official’ Arduino site with a lot of tutorials and examples, and a very usefull forum.